[Code of Federal Regulations]
[Title 21, Volume 8]
[Revised as of April 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR1020]
[Page 610-656]
TITLE 21--FOOD AND DRUGS
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN
SERVICES (CONTINUED)
PART 1020_PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING PRODUCTS
--Table of Contents
Sec.
1020.10 Television receivers.
1020.20 Cold-cathode gas discharge tubes.
1020.30 Diagnostic x-ray systems and their major components.
1020.31 Radiographic equipment.
1020.32 Fluoroscopic equipment.
1020.33 Computed tomography (CT) equipment.
1020.40 Cabinet x-ray systems.
Authority: 21 U.S.C. 351, 352, 360e-360j, 360gg-360ss, 371, 381.
Source: 38 FR 28632, Oct. 15, 1973, unless otherwise noted.
Sec. 1020.10 Television receivers.
(a) Applicability. The provisions of this section are applicable to
television receivers manufactured subsequent to January 15, 1970.
(b) Definitions. (1) External surface means the cabinet or enclosure
provided by the manufacturer as part of the receiver. If a cabinet or
enclosure is not provided as part of the receiver, the external surface
shall be considered to be a hypothetical cabinet, the plane surfaces of
which are located at those minimum distances from the chassis sufficient
to enclose all components of the receiver except that portion of the
neck and socket of the cathode-ray tube which normally extends beyond
the plane surfaces of the enclosure.
(2) Maximum test voltage means 130 root mean square volts if the
receiver is designed to operate from nominal 110 to 120 root mean square
volt power sources. If the receiver is designed to operate from a power
source having some voltage other than from nominal 110 to 120 root mean
square volts, maximum test voltage means 110 percent of the nominal root
mean square voltage specified by the manufacturer for the power source.
(3) Service controls means all of those controls on a television
receiver provided by the manufacturer for purposes of adjustment which,
under normal usage, are not accessible to the user.
(4) Television receiver means an electronic product designed to
receive and display a television picture through broadcast, cable, or
closed circuit television.
(5) Usable picture means a picture in synchronization and
transmitting viewable intelligence.
(6) User controls means all of those controls on a television
receiver, provided by the manufacturer for purposes of adjustment, which
on a fully assembled receiver under normal usage, are accessible to the
user.
(c) Requirements--(1) Exposure rate limit. Radiation exposure rates
produced by a television receiver shall not exceed 0.5 milliroentgens
per hour at a distance of five (5) centimeters from any point on the
external surface of the receiver, as measured in accordance with this
section.
(2) Measurements. Compliance with the exposure rate limit defined in
paragraph (c)(1) of this section shall be determined by measurements
made with an instrument, the radiation sensitive volume of which shall
have a cross section parallel to the external surface of the receiver
with an area of ten (10) square centimeters and no dimension larger than
five (5) centimeters. Measurements made with instruments having other
areas must be corrected for spatial nonuniformity of the radiation field
to obtain the exposure rate average over a ten (10) square centimeter
area.
(3) Test conditions. All measurements shall be made with the
receiver displaying a usable picture and with the power source operated
at supply
voltages up to the maximum test voltage of the receiver and, as
applicable, under the following specific conditions:
(i) On television receivers manufactured subsequent to January 15,
1970, measurements shall be made with all user controls adjusted so as
to produce maximum x-radiation emissions from the receiver.
(ii) On television receivers manufactured subsequent to June 1,
1970, measurements shall be made with all user controls and all service
controls adjusted to combinations which result in the production of
maximum x-radiation emissions.
(iii) On television receivers manufactured subsequent to June 1,
1971, measurements shall be made under the conditions described in
paragraph (c)(3) (ii) of this section, together with conditions
identical to those which result from that component or circuit failure
which maximizes x-radiation emissions.
(4) Critical component warning. The manufacturer shall permanently
affix or inscribe a warning label, clearly legible under conditions of
service, on all television receivers which could produce radiation
exposure rates in excess of the requirements of this section as a result
of failure or improper adjustment or improper replacement of a circuit
or shield component. The warning label shall include the specification
of operating high voltage and an instruction for adjusting the high
voltage to the specified value.
Return to Top
Sec. 1020.20 Cold-cathode gas discharge tubes.
(a) Applicability. The provisions of this section are applicable to
cold-cathode gas discharge tubes designed to demonstrate the effects of
a flow of electrons or the production of x-radiation as specified
herein.
(b) Definitions. Beam blocking device means a movable or removable
portion of any enclosure around a cold-cathode gas discharge tube, which
may be opened or closed to permit or prevent the emergence of an exit
beam.
Cold-cathode gas discharge tube means an electronic device in which
electron flow is produced and sustained by ionization of contained gas
atoms and ion bombardment of the cathode.
Exit beam means that portion of the radiation which passes through
the aperture resulting from the opening of the beam blocking device.
Exposure means the sum of the electrical charges on all of the ions
of one sign produced in air when all electrons liberated by photons in a
volume element of air are completely stopped in air divided by the mass
of the air in the volume element. The special unit of exposure is the
roentgen. One (1) roentgen equals 2.58x10<SUP>-4</SUP> coulombs/
kilogram.
(c) Requirements--(1) Exposure rate limit. (i) Radiation exposure
rates produced by cold-cathode gas discharge tubes shall not exceed 10
mR./hr. at a distance of thirty (30) centimeters from any point on the
external surface of the tube, as measured in accordance with this
section.
(ii) The divergence of the exit beam from tubes designed primarily
to demonstrate the effects of x radiation, with the beam blocking device
in the open position, shall not exceed (Pi) steradians.
(2) Measurements. (i) Compliance with the exposure rate limit
defined in paragraph (c)(1)(i) of this section shall be determined by
measurements averaged over an area of one hundred (100) square
centimeters with no linear dimension greater than twenty (20)
centimeters.
(ii) Measurements of exposure rates from tubes in enclosures from
which the tubes cannot be removed without destroying the function of the
tube may be made at a distance of thirty (30) centimeters from any point
on the external surface of the enclosure, provided:
(a) In the case of enclosures containing tubes designed primarily to
demonstrate the production of x radiation, measurements shall be made
with any beam blocking device in the beam blocking position, or
(b) In the case of enclosures containing tubes designed primarily to
demonstrate the effects of a flow of electrons, measurements shall be
made with all movable or removable parts of such enclosure in the
position which would maximize external exposure levels.
(3) Test conditions. (i) Measurements shall be made under the
conditions of use specified in instructions provided by the
manufacturer.
(ii) Measurements shall be made with the tube operated under forward
and reverse polarity.
(4) Instructions, labels, and warnings. (i) Manufacturers shall
provide, or cause to be provided, with each tube to which this section
is applicable, appropriate safety instructions, together with
instructions for the use of such tube, including the specification of a
power source for use with the tube.
(ii) Each enclosure or tube shall have inscribed on or permanently
affixed to it, tags or labels, which identify the intended polarity of
the terminals and:
(a) In the case of tubes designed primarily to demonstrate the heat
effect, fluorescence effect, or magnetic effect, a warning that
application of power in excess of that specified may result in the
production of x-rays in excess of allowable limits; and (b) in the case
of tubes designed primarily to demonstrate the production of x-
radiation, a warning that this device produces x-rays when energized.
(iii) The tag or label required by this paragraph shall be located
on the tube or enclosure so as to be readily visible and legible when
the product is fully assembled for use.
Return to Top
Sec. 1020.30 Diagnostic x-ray systems and their major components.
(a) Applicability--(1) The provisions of this section are applicable
to:
(i) The following components of diagnostic x-ray systems:
(A) Tube housing assemblies, x-ray controls, x-ray high-voltage
generators, x-ray tables, cradles, film changers, vertical cassette
holders mounted in a fixed location and cassette holders with front
panels, and beam-limiting devices manufactured after August 1, 1974.
(B) Fluoroscopic imaging assemblies manufactured after August 1,
1974, and before April 26, 1977.
(C) Spot-film devices and image intensifiers manufactured after
April 26, 1977.
(D) Cephalometric devices manufactured after February 25, 1978.
(E) Image receptor support devices for mammographic x-ray systems
manufactured after September 5, 1978.
(ii) Diagnostic x-ray systems, except computed tomography x-ray
systems, incorporating one or more of such components; however, such x-
ray systems shall be required to comply only with those provisions of
this section and Sec. Sec. 1020.31 and 1020.32 which relate to the
components certified in accordance with paragraph (c) of this section
and installed into the systems.
(iii) Computed tomography (CT) x-ray systems manufactured before
November 29, 1984.
(iv) CT gantries manufactured after September 3, 1985.
(2) The following provisions of this section and Sec. 1020.33 are
applicable to CT x-ray systems manufactured or remanufactured on or
after November 29, 1984:
(i) Section 1020.30(a);
(ii) Section 1020.30(b) ``Technique factors'';
(iii) Section 1020.30(b) ``CT,'' ``Dose,'' ``Scan,'' ``Scan time,''
and ``Tomogram'';
(iv) Section 1020.30 (h)(3)(vi) through (h)(3)(viii);
(v) Section 1020.30(n);
(vi) Section 1020.33 (a) and (b);
(vii) Section 1020.33(c)(1) as it affects Sec. 1020.33(c)(2); and
(viii) Section 1020.33(c)(2).
(3) The provisions of this section and Sec. 1020.33 in its
entirety, including those provisions in paragraph (a)(2) of this
section, are applicable to CT x-ray systems manufactured or
remanufactured on or after September 3, 1985. The date of manufacture of
the CT system is the date of manufacture of the CT gantry.
(b) Definitions. As used in this section and Sec. Sec. 1020.31,
1020.32, and 1020.33, the following definitions apply:
Accessible surface means the external surface of the enclosure or
housing provided by the manufacturer.
Accessory component means:
(1) A component used with diagnostic x-ray systems, such as a cradle
or film changer, that is not necessary for the compliance of the system
with applicable provisions of this subchapter but which requires an
initial determination of compatibility with the system; or
(2) A component necessary for compliance of the system with
applicable provisions of this subchapter but which may be interchanged
with similar compatible components without affecting the system's
compliance, such as one of a set of interchangeable beam-limiting
devices; or
(3) A component compatible with all x-ray systems with which it may
be used and that does not require compatibility or installation
instructions, such as a tabletop cassette holder.
Aluminum equivalent means the thickness of aluminum (type 1100
alloy) \1\ affording the same attenuation, under specified conditions as
the material in question.
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\1\ The nominal chemical composition of type 1100 aluminum alloy is
99.00 percent minimum aluminum, 0.12 percent copper, as given in
``Aluminum Standards and Data'' (1969). Copies may be obtained from: The
Aluminum Association, New York, NY.
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Articulated joint means a joint between two separate sections of a
tabletop which joint provides the capacity for one of the sections to
pivot on the line segment along which the sections join.
Assembler means any person engaged in the business of assembling,
replacing, or installing one or more components into a diagnostic x-ray
system or subsystem. The term includes the owner of an x-ray system or
his or her employee or agent who assembles components into an x-ray
system that is subsequently used to provide professional or commercial
services.
Attenuation block means a block or stack of type 1100 aluminum alloy
or aluminum alloy having equivalent attenuation with dimensions 20
centimeters by 20 centimeters by 3.8 centimeters.
Automatic exposure control means a device which automatically
controls one or more technique factors in order to obtain at a
preselected location(s) a required quantity of radiation.
Beam axis means a line from the source through the centers of the x-
ray fields.
Beam-limiting device means a device which provides a means to
restrict the dimensions of the x-ray field.
Cantilevered tabletop means a tabletop designed such that the
unsupported portion can be extended at least 100 centimeters beyond the
support.
Cassette holder means a device, other than a spot-film device, that
supports and/or fixes the position of an x-ray film cassette during an
x-ray exposure.
Cephalometric device means a device intended for the radiographic
visualization and measurement of the dimensions of the human head.
Coefficient of variation means the ratio of the standard deviation
to the mean value of a population of observations. It is estimated using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR01FE93.030
where:
s = Estimated standard deviation of the population.
X = Mean value of observations in sample.
X<INF>i</INF> = ith observation sampled.
n = Number of observations sampled.
Computed tomography (CT) means the production of a tomogram by the
acquisition and computer processing of x-ray transmission data.
Control panel means that part of the x-ray control upon which are
mounted the switches, knobs, pushbuttons, and other hardware necessary
for manually setting the technique factors.
Cooling curve means the graphical relationship between heat units
stored and cooling time.
Cradle means:
(1) A removable device which supports and may restrain a patient
above an x-ray table; or
(2) A device;
(i) Whose patient support structure is interposed between the
patient and the image receptor during normal use;
(ii) Which is equipped with means for patient restraint; and
(iii) Which is capable of rotation about its long (longitudinal)
axis.
CT gantry means tube housing assemblies, beam-limiting devices,
detectors, and the supporting structures, frames, and covers which hold
and/or enclose these components.
Diagnostic source assembly means the tube housing assembly with a
beam-limiting device attached.
Diagnostic x-ray system means an x-ray system designed for
irradiation of any part of the human body for the purpose of diagnosis
or visualization.
Dose means the absorbed dose as defined by the International
Commission on Radiation Units and Measurements. The absorbed dose, D, is
the quotient of de by dm, where de is the mean energy imparted by
ionizing radiation to matter of mass dm.
Equipment means x-ray equipment.
Exposure means the quotient of dQ by dm where dQ is the absolute
value of the total charge of the ions of one sign produced in air when
all the electrons (negatrons and positrons) liberated by photons in a
volume element of air having mass dm are completely stopped in air.
Field emission equipment means equipment which uses an x-ray tube in
which electron emission from the cathode is due solely to action of an
electric field.
Fluoroscopic imaging assembly means a subsystem in which x-ray
photons produce a fluoroscopic image. It includes the image receptor(s)
such as the image intensifier and spot-film device, electrical
interlocks, if any, and structural material providing linkage between
the image receptor and diagnostic source assembly.
General purpose radiographic x-ray system means any radiographic x-
ray system which, by design, is not limited to radiographic examination
of specific anatomical regions.
Half-value layer (HVL) means the thickness of specified material
which attenuates the beam of radiation to an extent such that the
exposure rate is reduced to one-half of its original value. In this
definition the contribution of all scattered radiation, other than any
which might be present initially in the beam concerned, is deemed to be
excluded.
Image intensifier means a device, installed in its housing, which
instantaneously converts an x-ray pattern into a corresponding light
image of higher energy density.
Image receptor means any device, such as a fluorescent screen,
radiographic film, solid-state detector, or gaseous detector, which
transforms incident x-ray photons either into a visible image or into
another form which can be made into a visible image by further
transformations. In those cases where means are provided to preselect a
portion of the image receptor, the term ``image receptor'' shall mean
the preselected portion of the device.
Image receptor support device means, for mammography x-ray systems,
that part of the system designed to support the image receptor during a
mammographic examination and to provide a primary protective barrier.
Leakage radiation means radiation emanating from the diagnostic
source assembly except for:
(1) The useful beam; and
(2) Radiation produced when the exposure switch or timer is not
activated.
Leakage technique factors means the technique factors associated
with the diagnostic source assembly which are used in measuring leakage
radiation. They are defined as follows:
(1) For diagnostic source assemblies intended for capacitor energy
storage equipment, the maximum-rated peak tube potential and the
maximum-rated number of exposures in an hour for operation at the
maximum-rated peak tube potential with the quantity of charge per
exposure being 10 millicoulombs (or 10 mAs) or the minimum obtainable
from the unit, whichever is larger;
(2) For diagnostic source assemblies intended for field emission
equipment rated for pulsed operation, the maximum-rated peak tube
potential and the maximum-rated number of x-ray pulses in an hour for
operation at the maximum-rated peak tube potential; and
(3) For all other diagnostic source assemblies, the maximum-rated
continuous tube current for the maximum-rated continuous tube current
for the maximum-rated peak tube potential.
Light field means that area of the intersection of the light beam
from the beam-limiting device and one of the set of planes parallel to
and including the plane of the image receptor, whose perimeter is the
locus of points at which the illuminance is one-fourth of the maximum in
the intersection.
Line-voltage regulation means the difference between the no-load and
the load line potentials expressed as a percent of the load line
potential; that is, Percent line-voltage regulation
[GRAPHIC] [TIFF OMITTED] TC01AP93.002
where:
V<INF>n</INF> = No-load line potential and
V<INF>i</INF> = Load line potential.
Maximum line current means the root mean square current in the
supply line of an x-ray machine operating at its maximum rating.
Movable tabletop means a tabletop which, when assembled for use, is
capable of movement with respect to its supporting structure within the
plane of the tabletop.
Peak tube potential means the maximum value of the potential
difference across the x-ray tube during an exposure.
Primary protective barrier means the material, excluding filters,
placed in the useful beam to reduce the radiation exposure for
protection purposes.
Pulsed mode means operation of the x-ray system such that the x-ray
tube current is pulsed by the x-ray control to produce one or more
exposure intervals of duration less than one-half second.
Quick change x-ray tube means an x-ray tube designed for use in its
associated tube housing such that:
(1) The tube cannot be inserted in its housing in a manner that
would result in noncompliance of the system with the requirements of
paragraphs (k) and (m) of this section;
(2) The focal spot position will not cause noncompliance with the
provisions of this section or Sec. 1020.31 or Sec. 1020.32;
(3) The shielding within the tube housing cannot be displaced; and
(4) Any removal and subsequent replacement of a beam-limiting device
during reloading of the tube in the tube housing will not result in
noncompliance of the x-ray system with the applicable field limitation
and alignment requirements of Sec. Sec. 1020.31 and 1020.32.
Radiation therapy simulation system means a radiographic or
fluoroscopic x-ray system intended for localizing the volume to be
exposed during radiation therapy and confirming the position and size of
the therapeutic irradiation field.
Rated line voltage means the range of potentials, in volts, of the
supply line specified by the manufacturer at which the x-ray machine is
designed to operate.
Rated output current means the maximum allowable load current of the
x-ray high-voltage generator.
Rated output voltage means the allowable peak potential, in volts,
at the output terminals of the x-ray high-voltage generator.
Rating means the operating limits specified by the manufacturer.
Recording means producing a permanent form of an image resulting
from x-ray photons (e.g., film, videotape).
Scan means the complete process of collecting x-ray transmission
data for the production of a tomogram. Data may be collected
simultaneously during a single scan for the production of one or more
tomograms.
Scan time means the period of time between the beginning and end of
x-ray transmission data accumulation for a single scan.
Source means the focal spot of the x-ray tube.
Source-image receptor distance (SID) means the distance from the
source to the center of the input surface of the image receptor.
Spot-film device means a device intended to transport and/or
position a radiographic image receptor between the x-ray source and
fluoroscopic image receptor. It includes a device intended to hold a
cassette over the input end of an image intensifier for the purpose of a
radiograph.
Stationary tabletop means a tabletop which, when assembled for use,
is incapable of movement with respect to its supporting structure within
the plane of the tabletop.
Technique factors means the following conditions of operation:
(1) For capacitor energy storage equipment, peak tube potential in
kilovolts (kV) and quantity of charge in milliamperes-seconds (mAs);
(2) For field emission equipment rated for pulsed operation, peak
tube potential in kV and number of x-ray pulses;
(3) For CT equipment designed for pulsed operation, peak tube
potential in kV, scan time in seconds, and either tube current in
milliamperes (mA), x-ray pulse width in seconds, and the number of x-ray
pulses per scan, or the product of the tube current, x-ray pulse width,
and the number of x-ray pulses in mAs;
(4) For CT equipment not designed for pulsed operation, peak tube
potential in kV, and either tube current in mA and scan time in seconds,
or the product of tube current and exposure time in mAs and the scan
time when the scan time and exposure time are equivalent; and
(5) For all other equipment, peak tube potential in kV, and either
tube current in mA and exposure time in seconds, or the product of tube
current and exposure time in mAs.
Tomogram means the depiction of the x-ray attenuation properties of
a section through a body.
Tube means an x-ray tube, unless otherwise specified.
Tube housing assembly means the tube housing with tube installed. It
includes high-voltage and/or filament transformers and other appropriate
elements when they are contained within the tube housing.
Tube rating chart means the set of curves which specify the rated
limits of operation of the tube in terms of the technique factors.
Useful beam means the radiation which passes through the tube
housing port and the aperture of the beam-limiting device when the
exposure switch or timer is activated.
Variable-aperture beam-limiting device means a beam-limiting device
which has the capacity for stepless adjustment of the x-ray field size
at a given SID.
Visible area means the portion of the input surface of the image
receptor over which incident x-ray photons are producing a visible
image.
X-ray control means a device which controls input power to the x-ray
high-voltage generator and/or the x-ray tube. It includes equipment such
as timers, phototimers, automatic brightness stabilizers, and similar
devices, which control the technique factors of an x-ray exposure.
X-ray equipment means an x-ray system, subsystem, or component
thereof. Types of x-ray equipment are as follows:
(1) Mobile x-ray equipment means x-ray equipment mounted on a
permanent base with wheels and/or casters for moving while completely
assembled;
(2) Portable x-ray equipment means x-ray equipment designed to be
hand-carried; and
(3) Stationary x-ray equipment means x-ray equipment which is
installed in a fixed location.
X-ray field means that area of the intersection of the useful beam
and any one of the set of planes parallel to and including the plane of
the image receptor, whose perimeter is the locus of points at which the
exposure rate is one-fourth of the maximum in the intersection.
X-ray high-voltage generator means a device which transforms
electrical energy from the potential supplied by the x-ray control to
the tube operating potential. The device may also include means for
transforming alternating current to direct current, filament
transformers for the x-ray tube(s), high-voltage switches, electrical
protective devices, and other appropriate elements.
X-ray system means an assemblage of components for the controlled
production of x-rays. It includes minimally an x-ray high-voltage
generator, an x-ray control, a tube housing assembly, a beam-limiting
device, and the necessary supporting structures. Additional components
which function with the system are considered integral parts of the
system.
X-ray subsystem means any combination of two or more components of
an x-ray system for which there are requirements specified in this
section and Sec. Sec. 1020.31 and 1020.32.
X-ray table means a patient support device with its patient support
structure (tabletop) interposed between the patient and the image
receptor during radiography and/or fluoroscopy. This includes, but is
not limited to, any stretcher equipped with a radiolucent panel and any
table equipped with a cassette tray (or bucky), cassette tunnel, image
intensifier, or spot-film device beneath the tabletop.
X-ray tube means any electron tube which is designed for the
conversion of electrical energy into x-ray energy.
(c) Manufacturers' responsibility. Manufacturers of products subject
to Sec. Sec. 1020.30 through 1020.33 shall certify that each of their
products meet all applicable requirements when installed into a
diagnostic x-ray system according to instructions. This certification
shall be made under the format specified in Sec. 1010.2 of this
chapter. Manufacturers may certify a combination of two or more
components if they obtain prior authorization in writing from the
Director of the Office of Compliance and Surveillance of the Center for
Devices and Radiological Health. Manufacturers shall not be held
responsible for noncompliance of their products if that noncompliance is
due solely to the improper installation or assembly of that product by
another person; however, manufacturers are responsible for providing
assembly instructions adequate to assure compliance of their components
with the applicable provisions of Sec. Sec. 1020.30 through 1020.33.
(d) Assemblers' responsibility. An assembler who installs one or
more components certified as required by paragraph (c) of this section
shall install certified components that are of the type required by
Sec. Sec. 1020.31, 1020.32, or 1020.33 and shall assemble, install,
adjust, and test the certified components according to the instructions
of their respective manufacturers. Assemblers shall not be liable for
noncompliance of a certified component if the assembly of that component
was according to the component manufacturer's instruction.
(1) Reports of assembly. All assemblers who install certified
components shall file a report of assembly, except as specified in
paragraph (d)(2) of this section. The report will be construed as the
assembler's certification and identification under Sec. Sec. 1010.2 and
1010.3 of this chapter. The assembler shall affirm in the report that
the manufacturer's instructions were followed in the assembly or that
the certified components as assembled into the system meet all
applicable requirements of Sec. Sec. 1020.30 through 1020.33. All
assembler reports must be on a form prescribed by and available from the
Director, Center for Devices and Radiological Health, 9200 Corporate
Blvd., Rockville, MD 20850. Completed reports must be submitted to the
Director, the purchaser, and, where applicable, to the State agency
responsible for radiation protection within 15 days following completion
of the assembly.
(2) Exceptions to reporting requirements. Reports of assembly need
not be submitted for any of the following:
(i) Reloaded or replacement tube housing assemblies that are
reinstalled in or newly assembled into an existing x-ray system;
(ii) Certified accessory components that have been identified as
such to the Center for Devices and Radiological Health in the report
required under Sec. 1002.10 of this chapter;
(iii) Repaired components, whether or not removed from the system
and reinstalled during the course of repair, provided the original
installation into the system was reported; or
(iv) Components installed temporarily in an x-ray system in place of
components removed temporarily for repair, provided the temporarily
installed component is identified by a tag or label bearing the
following information:
Temporarily Installed Component
This certified component has been assembled, installed, adjusted,
and tested by me according to the instructions provided by the
manufacturer.
Signature
Company Name
Street Address, P.O. Box
City, State, Zip Code
Date of Installation
The replacement of the temporarily installed component by a
component other than the component originally removed for repair shall
be reported as specified in paragraph (d)(1) of this section.
(e) Identification of x-ray components. In addition to the
identification requirements specified in Sec. 1010.3 of this chapter,
manufacturers of components subject to this section and Sec. Sec.
1020.31, 1020.32, and 1020.33, except high-voltage generators contained
within tube housings and beam-limiting devices that are integral parts
of tube housings, shall permanently inscribe or affix thereon the model
number and serial number of the product so that they are legible and
accessible to view. The word ``model'' or ``type'' shall appear as part
of the manufacturer's required identification of certified x-ray
components. Where the certification of a system or subsystem, consisting
of two or more components, has been authorized pursuant to paragraph (c)
of this section, a single inscription, tag, or label bearing the model
number and serial number may be used to identify the product.
(1) Tube housing assemblies. In a similar manner, manufacturers of
tube housing assemblies shall also inscribe or affix thereon the name of
the manufacturer, model number, and serial number of the x-ray tube
which the tube housing assembly incorporates.
(2) Replacement of tubes. Except as specified in paragraph (e)(3) of
this section, the replacement of an x-ray tube in a previously
manufactured tube housing assembly certified pursuant to paragraph (c)
of this section constitutes manufacture of a new tube housing assembly,
and the manufacturer is subject to the provisions of paragraph (e)(1) of
this section. The manufacturer shall remove, cover, or deface any
previously affixed inscriptions, tags, or labels, that are no longer
applicable.
(3) Quick-change x-ray tubes. The requirements of paragraph (e)(2)
of this section shall not apply to tube housing assemblies designed and
designated by their original manufacturer to contain quick change x-ray
tubes. The manufacturer of quick-change x-ray tubes shall include with
each replacement tube a label with the tube manufacturer's name, the
model, and serial number of the x-ray tube. The manufacturer of the tube
shall instruct the assembler who installs the new tube to attach the
label to the tube housing assembly and to remove, cover, or deface the
previously affixed inscriptions, tags, or labels that are described by
the tube manufacturer as no longer applicable.
(f) [Reserved]
(g) Information to be provided to assemblers. Manufacturers of
components listed in paragraph (a)(1) of this section shall provide to
assemblers subject to paragraph (d) of this section and, upon request,
to others at a cost not to exceed the cost of publication and
distribution, instructions for assembly, installation, adjustment, and
testing of such components adequate to assure that the products will
comply with applicable provisions of this section and Sec. Sec.
1020.31, 1020.32, and 1020.33, when assembled, installed, adjusted, and
tested as directed. Such instructions shall include specifications of
other components compatible with that to be installed when compliance of
the system or subsystem depends on their compatibility. Such
specifications may describe pertinent physical characteristics of the
components and/or may list by manufacturer model number the components
which are compatible. For x-ray controls and generators manufactured
after May 3, 1994, manufacturers shall provide:
(1) A statement of the rated line voltage and the range of line-
voltage regulation for operation at maximum line current;
(2) A statement of the maximum line current of the x-ray system
based on the maximum input voltage and current characteristics of the
tube housing assembly compatible with rated output voltage and rated
output current characteristics of the x-ray control and associated high-
voltage generator. If the rated input voltage and current
characteristics of the tube housing assembly are not known by the
manufacturer of the x-ray control and associated high-voltage generator,
he shall provide necessary information to allow the assembler to
determine the
maximum line current for the particular tube housing assembly(ies);
(3) A statement of the technique factors that constitute the maximum
line current condition described in paragraph (g)(2) of this section.
(h) Information to be provided to users. Manufacturers of x-ray
equipment shall provide to purchasers and, upon request, to others at a
cost not to exceed the cost of publication and distribution, manuals or
instruction sheets which shall include the following technical and
safety information:
(1) All x-ray equipment. For x-ray equipment to which this section
and Sec. Sec. 1020.31, 1020.32, and 1020.33 are applicable, there shall
be provided:
(i) Adequate instructions concerning any radiological safety
procedures and precautions which may be necessary because of unique
features of the equipment; and
(ii) A schedule of the maintenance necessary to keep the equipment
in compliance with this section and Sec. Sec. 1020.31, 1020.32, and
1020.33.
(2) Tube housing assemblies. For each tube housing assembly, there
shall be provided:
(i) Statements of the leakage technique factors for all combinations
of tube housing assemblies and beam-limiting devices for which the tube
housing assembly manufacturer states compatibility, the minimum
filtration permanently in the useful beam expressed as millimeters of
aluminum equivalent, and the peak tube potential at which the aluminum
equivalent was obtained;
(ii) Cooling curves for the anode and tube housing; and
(iii) Tube rating charts. If the tube is designed to operate from
different types of x-ray high-voltage generators (such as single-phase
self rectified, single-phase half-wave rectified, single-phase full-wave
rectified, 3-phase 6-pulse, 3-phase 12-pulse, constant potential,
capacitor energy storage) or under modes of operation such as alternate
focal spot sizes or speeds of anode rotation which affect its rating,
specific identification of the difference in ratings shall be noted.
(3) X-ray controls and generators. For the x-ray control and
associated x-ray high-voltage generator, there shall be provided:
(i) A statement of the rated line voltage and the range of line-
voltage regulation for operation at maximum line current;
(ii) A statement of the maximum line current of the x-ray system
based on the maximum input voltage and output current characteristics of
the tube housing assembly compatible with rated output voltage and rated
current characteristics of the x-ray control and associated high-voltage
generator. If the rated input voltage and current characteristics of the
tube housing assembly are not known by the manufacturer of the x-ray
control and associated high-voltage generator, the manufacturer shall
provide necessary information to allow the purchaser to determine the
maximum line current for his particular tube housing assembly(ies);
(iii) A statement of the technique factors that constitute the
maximum line current condition described in paragraph (h)(3)(ii) of this
section;
(iv) In the case of battery-powered generators, a specification of
the minimum state of charge necessary for proper operation;
(v) Generator rating and duty cycle;
(vi) A statement of the maximum deviation from the preindication
given by labeled technique factor control settings or indicators during
any radiographic or CT exposure where the equipment is connected to a
power supply as described in accordance with this paragraph. In the case
of fixed technique factors, the maximum deviation from the nominal fixed
value of each factor shall be stated;
(vii) A statement of the maximum deviation from the continuous
indication of x-ray tube potential and current during any fluoroscopic
exposure when the equipment is connected to a power supply as described
in accordance with this paragraph; and
(viii) A statement describing the measurement criteria for all
technique factors used in paragraphs (h)(3)(iii), (h)(3)(vi), and
(h)(3)(vii) of this section; for example, the beginning and endpoints of
exposure time measured with respect to a certain percentage of the
voltage waveform.
(4) Beam-limiting device. For each variable-aperture beam-limiting
device, there shall be provided;
(i) Leakage technique factors for all combinations of tube housing
assemblies and beam-limiting devices for which the beam-limiting device
manufacturer states compatibility; and
(ii) A statement including the minimum aluminum equivalent of that
part of the device through which the useful beam passes and including
the x-ray tube potential at which the aluminum equivalent was obtained.
When two or more filters are provided as part of the device, the
statement shall include the aluminum equivalent of each filter.
(i) [Reserved]
(j) Warning label. The control panel containing the main power
switch shall bear the warning statement, legible and accessible to view:
``Warning: This x-ray unit may be dangerous to patient and operator
unless safe exposure factors and operating instructions are observed.''
(k) Leakage radiation from the diagnostic source assembly. The
leakage radiation from the diagnostic source assembly measured at a
distance of 1 meter in any direction from the source shall not exceed
2.58x10<SUP>-5</SUP> coulombs per kilogram (C/kg) (100 milliroentgens
(mR)) in 1 hour when the x-ray tube is operated at the leakage technique
factors. If the maximum rated peak tube potential of the tube housing
assembly is greater than the maximum rated peak tube potential for the
diagnostic source assembly, positive means shall be provided to limit
the maximum x-ray tube potential to that of the diagnostic source
assembly. Compliance shall be determined by measurements averaged over
an area of 100 square centimeters with no linear dimension greater than
20 centimeters.
(l) Radiation from components other than the diagnostic source
assembly. The radiation emitted by a component other than the diagnostic
source assembly shall not exceed 5.16x10<SUP>-7</SUP> C/kg (2 mR) in 1
hour at 5 centimeters from any accessible surface of the component when
it is operated in an assembled x-ray system under any conditions for
which it was designed. Compliance shall be determined by measurements
averaged over an area of 100 square centimeters with no linear dimension
greater than 20 centimeters.
(m) Beam quality--(1) Half-value layer. The half-value layer (HVL)
of the useful beam for a given x-ray tube potential shall not be less
than the appropriate value shown in table I under ``Specified dental
systems,'' for any dental x-ray system designed for use with intraoral
image receptors and manufactured after December 1, 1980; and under
``Other x-ray systems,'' for all other x-ray systems subject to this
section. If it is necessary to determine such HVL at an x-ray tube
potential which is not listed in table I, linear interpolation or
extrapolation may be made. Positive means \2\ shall be provided to
insure that at least the minimum filtration needed to achieve the above
beam quality requirements is in the useful beam during each exposure.
---------------------------------------------------------------------------
\2\ In the case of a system which is to be operated with more than
one thickness of filtration, this requirement can be met by a filter
interlock with the kilovoltage selector which will prevent x-ray
emission if the minimum required filtration is not in place.
Table I
------------------------------------------------------------------------
X-ray tube voltage (kilovolt peak) Minimum HVL
--------------------------------------------------- (millimeters of
aluminum)
Measured ---------------------
Designed operating range operating Specified Other X-
potential dental ray
systems systems
------------------------------------------------------------------------
Below 51............................... 30 1.5 0.3
40 1.5 0.4
50 1.5 0.5
51 to 70............................... 51 1.5 1.2
60 1.5 1.3
70 1.5 1.5
Above 70............................... 71 2.1 2.1
80 2.3 2.3
90 2.5 2.5
100 2.7 2.7
110 3.0 3.0
120 3.2 3.2
130 3.5 3.5
140 3.8 3.8
150 4.1 4.1
------------------------------------------------------------------------
(2) Measuring compliance. For capacitor energy storage equipment,
compliance shall be determined with the maximum selectable quantity of
charge per exposure.
(n) Aluminum equivalent of material between patient and image
receptor. Except when used in a CT x-ray system, the aluminum equivalent
of each of the items listed in table II, which are used
between the patient and image receptor, may not exceed the indicated
limits. Compliance shall be determined by x-ray measurements made at a
potential of 100 kilovolts peak and with an x-ray beam that has a HVL of
2.7 millimeters of aluminum. This requirement applies to front panel(s)
of cassette holders and film changers provided by the manufacturer for
patient support or for prevention of foreign object intrusions. It does
not apply to screens and their associated mechanical support panels or
grids.
Table II
------------------------------------------------------------------------
Aluminum
Item equivalent
(millimeters)
------------------------------------------------------------------------
Front panel(s) of cassette holder (total of all)........ 1.0
Front panel(s) of film changer (total of all)........... 1.0
Cradle.................................................. 2.0
Tabletop, stationary, without articulated joint(s)...... 1.0
Tabletop, movable, without articulated joint(s) 1.5
(including stationary subtop)..........................
Tabletop, with radiolucent panel having one articulated 1.5
joint..................................................
Tabletop, with radiolucent panel having two or more 2.0
articulated joints.....................................
Tabletop, cantilevered.................................. 2.0
Tabletop, radiation therapy simulator................... 5.0
------------------------------------------------------------------------
(o) Battery charge indicator. On battery-powered generators, visual
means shall be provided on the control panel to indicate whether the
battery is in a state of charge adequate for proper operation.
(p) [Reserved]
(q) Modification of certified diagnostic x-ray components and
systems--(1) Diagnostic x-ray components and systems certified in
accordance with Sec. 1010.2 of this chapter shall not be modified such
that the component or system fails to comply with any applicable
provision of this chapter unless a variance in accordance with Sec.
1010.4 of this chapter or an exemption under sections 358(a)(5) or
360B(b) of the Public Health Service Act has been granted.
(2) The owner of a diagnostic x-ray system who uses the system in a
professional or commercial capacity may modify the system, provided the
modification does not result in the failure of the system or component
to comply with the applicable requirements of this section or of Sec.
1020.31, Sec. 1020.32, or Sec. 1020.33. The owner who causes such
modification need not submit the reports required by subpart B of part
1002 of this chapter, provided the owner records the date and the
details of the modification, and provided the modification of the x-ray
system does not result in a failure to comply with Sec. 1020.31, Sec.
1020.32, or Sec. 1020.33.
[58 FR 26396, May 3, 1993, as amended at 59 FR 26403, May 19, 1994; 64
FR 35927, July 2, 1999; 65 FR 17138, Mar. 31, 2000]
Effective Date Note: At 70 FR 34028, June 10, 2005, Sec. 1020.30
was revised, effective June 10, 2006. For the convenience of the user
the revised text is set forth as follows:
Sec. 1020.30 Diagnostic x-ray systems and their major components.
(a) Applicability. (1) The provisions of this section are applicable
to:
(i) The following components of diagnostic x-ray systems:
(A) Tube housing assemblies, x-ray controls, x-ray high-voltage
generators, x-ray tables, cradles, film changers, vertical cassette
holders mounted in a fixed location and cassette holders with front
panels, and beam-limiting devices manufactured after August 1, 1974.
(B) Fluoroscopic imaging assemblies manufactured after August 1,
1974, and before April 26, 1977, or after June 10, 2006.
(C) Spot-film devices and image intensifiers manufactured after
April 26, 1977.
(D) Cephalometric devices manufactured after February 25, 1978.
(E) Image receptor support devices for mammographic x-ray systems
manufactured after September 5, 1978.
(F) Image receptors that are electrically powered or connected with
the x-ray system manufactured on or after June 10, 2006.
(G) Fluoroscopic air kerma display devices manufactured on or after
June 10, 2006.
(ii) Diagnostic x-ray systems, except computed tomography x-ray
systems, incorporating one or more of such components; however, such x-
ray systems shall be required to comply only with those provisions of
this section and Sec. Sec. 1020.31 and 1020.32, which relate to the
components certified in accordance with paragraph (c) of this section
and installed into the systems.
(iii) Computed tomography (CT) x-ray systems manufactured before
November 29, 1984.
(iv) CT gantries manufactured after September 3, 1985.
(2) The following provisions of this section and Sec. 1020.33 are
applicable to CT x-ray systems manufactured or remanufactured on or
after November 29, 1984:
(i) Section 1020.30(a);
(ii) Section 1020.30(b) ``Technique factors'';
(iii) Section 1020.30(b) ``CT,'' ``Dose,'' ``Scan,'' ``Scan time,''
and ``Tomogram'';
(iv) Section 1020.30(h)(3)(vi) through (h)(3)(viii);
(v) Section 1020.30(n);
(vi) Section 1020.33(a) and (b);
(vii) Section 1020.33(c)(1) as it affects Sec. 1020.33(c)(2); and
(viii) Section 1020.33(c)(2).
(3) The provisions of this section and Sec. 1020.33 in its
entirety, including those provisions in paragraph (a)(2) of this
section, are applicable to CT x-ray systems manufactured or
remanufactured on or after September 3, 1985. The date of manufacture of
the CT system is the date of manufacture of the CT gantry.
(b) Definitions. As used in this section and Sec. Sec. 1020.31,
1020.32, and 1020.33, the following definitions apply:
Accessible surface means the external surface of the enclosure or
housing provided by the manufacturer.
Accessory component means:
(1) A component used with diagnostic x-ray systems, such as a cradle
or film changer, that is not necessary for the compliance of the system
with applicable provisions of this subchapter but which requires an
initial determination of compatibility with the system; or
(2) A component necessary for compliance of the system with
applicable provisions of this subchapter but which may be interchanged
with similar compatible components without affecting the system's
compliance, such as one of a set of interchangeable beam-limiting
devices; or
(3) A component compatible with all x-ray systems with which it may
be used and that does not require compatibility or installation
instructions, such as a tabletop cassette holder.
Air kerma means kerma in air (see definition of Kerma).
Air kerma rate (AKR) means the air kerma per unit time.
Aluminum equivalent means the thickness of aluminum (type 1100
alloy)\1\ affording the same attenuation, under specified conditions, as
the material in question.
---------------------------------------------------------------------------
\1\ The nominal chemical composition of type 1100 aluminum alloy is
99.00 percent minimum aluminum, 0.12 percent copper, as given in
``Aluminum Standards and Data'' (1969). Copies may be obtained from The
Aluminum Association, New York, NY.
---------------------------------------------------------------------------
Articulated joint means a joint between two separate sections of a
tabletop which joint provides the capacity for one of the sections to
pivot on the line segment along which the sections join.
Assembler means any person engaged in the business of assembling,
replacing, or installing one or more components into a diagnostic x-ray
system or subsystem. The term includes the owner of an x-ray system or
his or her employee or agent who assembles components into an x-ray
system that is subsequently used to provide professional or commercial
services.
Attenuation block means a block or stack of type 1100 aluminum
alloy, or aluminum alloy having equivalent attenuation, with dimensions
20 centimeters (cm) or larger by 20 cm or larger by 3.8 cm, that is
large enough to intercept the entire x-ray beam.
Automatic exposure control (AEC) means a device which automatically
controls one or more technique factors in order to obtain at a
preselected location(s) a required quantity of radiation.
Automatic exposure rate control (AERC) means a device which
automatically controls one or more technique factors in order to obtain
at a preselected location(s) a required quantity of radiation per unit
time.
Beam axis means a line from the source through the centers of the x-
ray fields.
Beam-limiting device means a device which provides a means to
restrict the dimensions of the x-ray field.
C-arm fluoroscope means a fluoroscopic x-ray system in which the
image receptor and the x-ray tube housing assembly are connected or
coordinated to maintain a spatial relationship. Such a system allows a
change in the direction of the beam axis with respect to the patient
without moving the patient.
Cantilevered tabletop means a tabletop designed such that the
unsupported portion can be extended at least 100 cm beyond the support.
Cassette holder means a device, other than a spot-film device, that
supports and/or fixes the position of an x-ray film cassette during an
x-ray exposure.
Cephalometric device means a device intended for the radiographic
visualization and measurement of the dimensions of the human head.
Coefficient of variation means the ratio of the standard deviation
to the mean value of a population of observations. It is estimated using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR10JN05.001
where:
s = Estimated standard deviation of the population.
X = Mean value of observations in sample.
X<INF>i</INF> = ith observation sampled.
n = Number of observations sampled.
Computed tomography (CT) means the production of a tomogram by the
acquisition and computer processing of x-ray transmission data.
Control panel means that part of the x-ray control upon which are
mounted the switches, knobs, pushbuttons, and other hardware necessary
for manually setting the technique factors.
Cooling curve means the graphical relationship between heat units
stored and cooling time.
Cradle means:
(1) A removable device which supports and may restrain a patient
above an x-ray table; or
(2) A device;
(i) Whose patient support structure is interposed between the
patient and the image receptor during normal use;
(ii) Which is equipped with means for patient restraint; and
(iii) Which is capable of rotation about its long (longitudinal)
axis.
CT gantry means tube housing assemblies, beam-limiting devices,
detectors, and the supporting structures, frames, and covers which hold
and/or enclose these components.
Cumulative air kerma means the total air kerma accrued from the
beginning of an examination or procedure and includes all contributions
from fluoroscopic and radiographic irradiation.
Diagnostic source assembly means the tube housing assembly with a
beam-limiting device attached.
Diagnostic x-ray system means an x-ray system designed for
irradiation of any part of the human body for the purpose of diagnosis
or visualization.
Dose means the absorbed dose as defined by the International
Commission on Radiation Units and Measurements. The absorbed dose, D, is
the quotient of de by dm, where de is the mean energy imparted to matter
of mass dm; thus D=de/dm, in units of J/kg, where the special name for
the unit of absorbed dose is gray (Gy).
Equipment means x-ray equipment.
Exposure (X) means the quotient of dQ by dm where dQ is the absolute
value of the total charge of the ions of one sign produced in air when
all the electrons and positrons liberated or created by photons in air
of mass dm are completely stopped in air; thus X=dQ/dm, in units of C/
kg. A second meaning of exposure is the process or condition during
which the x-ray tube produces x-ray radiation.
Field emission equipment means equipment which uses an x-ray tube in
which electron emission from the cathode is due solely to action of an
electric field.
Fluoroscopic air kerma display device means a device, subsystem, or
component that provides the display of AKR and cumulative air kerma
required by Sec. 1020.32(k). It includes radiation detectors, if any,
electronic and computer components, associated software, and data
displays.
Fluoroscopic imaging assembly means a subsystem in which x-ray
photons produce a set of fluoroscopic images or radiographic images
recorded from the fluoroscopic image receptor. It includes the image
receptor(s), electrical interlocks, if any, and structural material
providing linkage between the image receptor and diagnostic source
assembly.
Fluoroscopic irradiation time means the cumulative duration during
an examination or procedure of operator-applied continuous pressure to
the device, enabling x-ray tube activation in any fluoroscopic mode of
operation.
Fluoroscopy means a technique for generating x-ray images and
presenting them simultaneously and continuously as visible images. This
term has the same meaning as the term ``radioscopy'' in the standards of
the International Electrotechnical Commission.
General purpose radiographic x-ray system means any radiographic x-
ray system which, by design, is not limited to radiographic examination
of specific anatomical regions.
Half-value layer (HVL) means the thickness of specified material
which attenuates the beam of radiation to an extent such that the AKR is
reduced to one-half of its original value. In this definition the
contribution of all scattered radiation, other than any which might be
present initially in the beam concerned, is deemed to be excluded.
Image intensifier means a device, installed in its housing, which
instantaneously converts an x-ray pattern into a corresponding light
image of higher energy density.
Image receptor means any device, such as a fluorescent screen,
radiographic film, x-ray image intensifier tube, solid-state detector,
or gaseous detector, which transforms incident x-ray photons either into
a visible image or into another form which can be made into a visible
image by further transformations. In those cases where means are
provided to preselect a portion of the image receptor, the term ``image
receptor'' shall mean the preselected portion of the device.
Image receptor support device means, for mammography x-ray systems,
that part of the system designed to support the image receptor during a
mammographic examination and to provide a primary protective barrier.
Isocenter means the center of the smallest sphere through which the
beam axis passes when the equipment moves through a full range of
rotations about its common center.
Kerma means the quantity as defined by the International Commission
on Radiation Units and Measurements. The kerma, K, is the quotient of
dE<INF>tr</INF> by dm, where dE<INF>tr</INF> is the sum of the initial
kinetic energies of all the charged particles liberated by uncharged
particles in a mass dm of material; thus K=dE<INF>tr</INF>/dm, in units
of J/kg, where the special name for the unit of kerma is gray (Gy). When
the material is air, the quantity is referred to as ``air kerma.''
Last-image-hold (LIH) radiograph means an image obtained either by
retaining one or more fluoroscopic images, which may be temporally
integrated, at the end of a fluoroscopic exposure or by initiating a
separate and distinct radiographic exposure automatically and
immediately in conjunction with termination of the fluoroscopic
exposure.
Lateral fluoroscope means the x-ray tube and image receptor
combination in a biplane system dedicated to the lateral projection. It
consists of the lateral x-ray tube housing assembly and the lateral
image receptor that are fixed in position relative to the table with the
x-ray beam axis parallel to the plane of the table.
Leakage radiation means radiation emanating from the diagnostic
source assembly except for:
(1) The useful beam; and
(2) Radiation produced when the exposure switch or timer is not
activated.
Leakage technique factors means the technique factors associated
with the diagnostic source assembly which are used in measuring leakage
radiation. They are defined as follows:
(1) For diagnostic source assemblies intended for capacitor energy
storage equipment, the maximum-rated peak tube potential and the
maximum-rated number of exposures in an hour for operation at the
maximum-rated peak tube potential with the quantity of charge per
exposure being 10 millicoulombs (or 10 mAs) or the minimum obtainable
from the unit, whichever is larger;
(2) For diagnostic source assemblies intended for field emission
equipment rated for pulsed operation, the maximum-rated peak tube
potential and the maximum-rated number of x-ray pulses in an hour for
operation at the maximum-rated peak tube potential; and
(3) For all other diagnostic source assemblies, the maximum-rated
peak tube potential and the maximum-rated continuous tube current for
the maximum-rated peak tube potential.
Light field means that area of the intersection of the light beam
from the beam-limiting device and one of the set of planes parallel to
and including the plane of the image receptor, whose perimeter is the
locus of points at which the illuminance is one-fourth of the maximum in
the intersection.
Line-voltage regulation means the difference between the no-load and
the load line potentials expressed as a percent of the load line
potential; that is,
Percent line-voltage regulation = 100(V<INF>n</INF> - V<INF>i</INF>)/
V<INF>i</INF>
where:
V<INF>n</INF> = No-load line potential and
V<INF>i</INF> = Load line potential.
Maximum line current means the root mean square current in the
supply line of an x-ray machine operating at its maximum rating.
Mode of operation means, for fluoroscopic systems, a distinct method
of fluoroscopy or radiography provided by the manufacturer and selected
with a set of several technique factors or other control settings
uniquely associated with the mode. The set of distinct technique factors
and control settings for the mode may be selected by the operation of a
single control. Examples of distinct modes of operation include normal
fluoroscopy (analog or digital), high-level control fluoroscopy,
cineradiography (analog or digital), digital subtraction angiography,
electronic radiography using the fluoroscopic image receptor, and
photospot recording. In a specific mode of operation, certain system
variables affecting air kerma, AKR, or image quality, such as image
magnification, x-ray field size, pulse rate, pulse duration, number of
pulses, source-image receptor distance (SID), or optical aperture, may
be adjustable or may vary; their variation per se does not comprise a
mode of operation different from the one that has been selected.
Movable tabletop means a tabletop which, when assembled for use, is
capable of movement with respect to its supporting structure within the
plane of the tabletop.
Non-image-intensified fluoroscopy means fluoroscopy using only a
fluorescent screen.
Peak tube potential means the maximum value of the potential
difference across the x-ray tube during an exposure.
Primary protective barrier means the material, excluding filters,
placed in the useful beam to reduce the radiation exposure for
protection purposes.
Pulsed mode means operation of the x-ray system such that the x-ray
tube current is pulsed by the x-ray control to produce one or more
exposure intervals of duration less than one-half second.
Quick change x-ray tube means an x-ray tube designed for use in its
associated tube housing such that:
(1) The tube cannot be inserted in its housing in a manner that
would result in noncompliance of the system with the requirements of
paragraphs (k) and (m) of this section;
(2) The focal spot position will not cause noncompliance with the
provisions of this section or Sec. 1020.31 or 1020.32;
(3) The shielding within the tube housing cannot be displaced; and
(4) Any removal and subsequent replacement of a beam-limiting device
during reloading of the tube in the tube housing will not result in
noncompliance of the x-ray system with the applicable field limitation
and alignment requirements of Sec. Sec. 1020.31 and 1020.32.
Radiation therapy simulation system means a radiographic or
fluoroscopic x-ray system intended for localizing the volume to be
exposed during radiation therapy and confirming the position and size of
the therapeutic irradiation field.
Radiography means a technique for generating and recording an x-ray
pattern for the purpose of providing the user with an image(s) after
termination of the exposure.
Rated line voltage means the range of potentials, in volts, of the
supply line specified by the manufacturer at which the x-ray machine is
designed to operate.
Rated output current means the maximum allowable load current of the
x-ray high-voltage generator.
Rated output voltage means the allowable peak potential, in volts,
at the output terminals of the x-ray high-voltage generator.
Rating means the operating limits specified by the manufacturer.
Recording means producing a retrievable form of an image resulting
from x-ray photons.
Scan means the complete process of collecting x-ray transmission
data for the production of a tomogram. Data may be collected
simultaneously during a single scan for the production of one or more
tomograms.
Scan time means the period of time between the beginning and end of
x-ray transmission data accumulation for a single scan.
Solid state x-ray imaging device means an assembly, typically in a
rectangular panel configuration, that intercepts x-ray photons and
converts the photon energy into a modulated electronic signal
representative of the x-ray intensity over the area of the imaging
device. The electronic signal is then used to create an image for
display and/or storage.
Source means the focal spot of the x-ray tube.
Source-image receptor distance (SID) means the distance from the
source to the center of the input surface of the image receptor.
Source-skin distance (SSD) means the distance from the source to the
center of the entrant x-ray field in the plane tangent to the patient
skin surface.
Spot-film device means a device intended to transport and/or
position a radiographic image receptor between the x-ray source and
fluoroscopic image receptor. It includes a device intended to hold a
cassette over the input end of the fluoroscopic image receptor for the
purpose of producing a radiograph.
Stationary tabletop means a tabletop which, when assembled for use,
is incapable of movement with respect to its supporting structure within
the plane of the tabletop.
Technique factors means the following conditions of operation:
(1) For capacitor energy storage equipment, peak tube potential in
kilovolts (kV) and quantity of charge in milliampere-seconds (mAs);
(2) For field emission equipment rated for pulsed operation, peak
tube potential in kV and number of x-ray pulses;
(3) For CT equipment designed for pulsed operation, peak tube
potential in kV, scan time in seconds, and either tube current in
milliamperes (mA), x-ray pulse width in seconds, and the number of x-ray
pulses per scan, or the product of the tube current, x-ray pulse width,
and the number of x-ray pulses in mAs;
(4) For CT equipment not designed for pulsed operation, peak tube
potential in kV, and either tube current in mA and scan time in seconds,
or the product of tube current and exposure time in mAs and the scan
time when the scan time and exposure time are equivalent; and
(5) For all other equipment, peak tube potential in kV, and either
tube current in mA and exposure time in seconds, or the product of tube
current and exposure time in mAs.
Tomogram means the depiction of the x-ray attenuation properties of
a section through a body.
Tube means an x-ray tube, unless otherwise specified.
Tube housing assembly means the tube housing with tube installed. It
includes high-voltage and/or filament transformers and other
appropriate elements when they are contained within the tube housing.
Tube rating chart means the set of curves which specify the rated
limits of operation of the tube in terms of the technique factors.
Useful beam means the radiation which passes through the tube
housing port and the aperture of the beam-limiting device when the
exposure switch or timer is activated.
Variable-aperture beam-limiting device means a beam-limiting device
which has the capacity for stepless adjustment of the x-ray field size
at a given SID.
Visible area means the portion of the input surface of the image
receptor over which incident x-ray photons are producing a visible
image.
X-ray control means a device which controls input power to the x-ray
high-voltage generator and/or the x-ray tube. It includes equipment such
as timers, phototimers, automatic brightness stabilizers, and similar
devices, which control the technique factors of an x-ray exposure.
X-ray equipment means an x-ray system, subsystem, or component
thereof. Types of x-ray equipment are as follows:
(1) Mobile x-ray equipment means x-ray equipment mounted on a
permanent base with wheels and/or casters for moving while completely
assembled;
(2) Portable x-ray equipment means x-ray equipment designed to be
hand-carried; and
(3) Stationary x-ray equipment means x-ray equipment which is
installed in a fixed location.
X-ray field means that area of the intersection of the useful beam
and any one of the set of planes parallel to and including the plane of
the image receptor, whose perimeter is the locus of points at which the
AKR is one-fourth of the maximum in the intersection.
X-ray high-voltage generator means a device which transforms
electrical energy from the potential supplied by the x-ray control to
the tube operating potential. The device may also include means for
transforming alternating current to direct current, filament
transformers for the x-ray tube(s), high-voltage switches, electrical
protective devices, and other appropriate elements.
X-ray subsystem means any combination of two or more components of
an x-ray system for which there are requirements specified in this
section and Sec. Sec. 1020.31 and 1020.32.
X-ray system means an assemblage of components for the controlled
production of x-rays. It includes minimally an x-ray high-voltage
generator, an x-ray control, a tube housing assembly, a beam-limiting
device, and the necessary supporting structures. Additional components
which function with the system are considered integral parts of the
system.
X-ray table means a patient support device with its patient support
structure (tabletop) interposed between the patient and the image
receptor during radiography and/or fluoroscopy. This includes, but is
not limited to, any stretcher equipped with a radiolucent panel and any
table equipped with a cassette tray (or bucky), cassette tunnel,
fluoroscopic image receptor, or spot-film device beneath the tabletop.
X-ray tube means any electron tube which is designed for the
conversion of electrical energy into x-ray energy.
(c) Manufacturers' responsibility. Manufacturers of products subject
to Sec. Sec. 1020.30 through 1020.33 shall certify that each of their
products meet all applicable requirements when installed into a
diagnostic x-ray system according to instructions. This certification
shall be made under the format specified in Sec. 1010.2 of this
chapter. Manufacturers may certify a combination of two or more
components if they obtain prior authorization in writing from the
Director of the Office of Compliance of the Center for Devices and
Radiological Health (CDRH). Manufacturers shall not be held responsible
for noncompliance of their products if that noncompliance is due solely
to the improper installation or assembly of that product by another
person; however, manufacturers are responsible for providing assembly
instructions adequate to assure compliance of their components with the
applicable provisions of Sec. Sec. 1020.30 through 1020.33.
(d) Assemblers' responsibility. An assembler who installs one or
more components certified as required by paragraph (c) of this section
shall install certified components that are of the type required by
Sec. 1020.31, 1020.32, or 1020.33 and shall assemble, install, adjust,
and test the certified components according to the instructions of their
respective manufacturers. Assemblers shall not be liable for
noncompliance of a certified component if the assembly of that component
was according to the component manufacturer's instruction.
(1) Reports of assembly. All assemblers who install certified
components shall file a report of assembly, except as specified in
paragraph (d)(2) of this section. The report will be construed as the
assembler's certification and identification under Sec. Sec. 1010.2 and
1010.3 of this chapter. The assembler shall affirm in the report that
the manufacturer's instructions were followed in the assembly or that
the certified components as assembled into the system meet all
applicable requirements of Sec. Sec. 1020.30 through 1020.33. All
assembler reports must be on a form prescribed by the Director, CDRH.
Completed reports must be submitted to the Director, the purchaser, and,
where applicable, to the State agency responsible for radiation
protection within 15 days following completion of the assembly.
(2) Exceptions to reporting requirements. Reports of assembly need
not be submitted for any of the following:
(i) Reloaded or replacement tube housing assemblies that are
reinstalled in or newly assembled into an existing x-ray system;
(ii) Certified accessory components that have been identified as
such to CDRH in the report required under Sec. 1002.10 of this chapter;
(iii) Repaired components, whether or not removed from the system
and reinstalled during the course of repair, provided the original
installation into the system was reported; or
(iv)(A) Components installed temporarily in an x-ray system in place
of components removed temporarily for repair, provided the temporarily
installed component is identified by a tag or label bearing the
following information:
Temporarily Installed Component
This certified component has been assembled, installed, adjusted, and
tested by me according to the instructions provided by the manufacturer.
Signature
Company Name
Street Address, P.O. Box
City, State, Zip Code
Date of Installation
(B) The replacement of the temporarily installed component by a
component other than the component originally removed for repair shall
be reported as specified in paragraph (d)(1) of this section.
(e) Identification of x-ray components. In addition to the
identification requirements specified in Sec. 1010.3 of this chapter,
manufacturers of components subject to this section and Sec. Sec.
1020.31, 1020.32, and 1020.33, except high-voltage generators contained
within tube housings and beam-limiting devices that are integral parts
of tube housings, shall permanently inscribe or affix thereon the model
number and serial number of the product so that they are legible and
accessible to view. The word ``model'' or ``type'' shall appear as part
of the manufacturer's required identification of certified x-ray
components. Where the certification of a system or subsystem, consisting
of two or more components, has been authorized under paragraph (c) of
this section, a single inscription, tag, or label bearing the model
number and serial number may be used to identify the product.
(1) Tube housing assemblies. In a similar manner, manufacturers of
tube housing assemblies shall also inscribe or affix thereon the name of
the manufacturer, model number, and serial number of the x-ray tube
which the tube housing assembly incorporates.
(2) Replacement of tubes. Except as specified in paragraph (e)(3) of
this section, the replacement of an x-ray tube in a previously
manufactured tube housing assembly certified under paragraph (c) of this
section constitutes manufacture of a new tube housing assembly, and the
manufacturer is subject to the provisions of paragraph (e)(1) of this
section. The manufacturer shall remove, cover, or deface any previously
affixed inscriptions, tags, or labels that are no longer applicable.
(3) Quick-change x-ray tubes. The requirements of paragraph (e)(2)
of this section shall not apply to tube housing assemblies designed and
designated by their original manufacturer to contain quick change x-ray
tubes. The manufacturer of quick-change x-ray tubes shall include with
each replacement tube a label with the tube manufacturer's name, the
model, and serial number of the x-ray tube. The manufacturer of the tube
shall instruct the assembler who installs the new tube to attach the
label to the tube housing assembly and to remove, cover, or deface the
previously affixed inscriptions, tags, or labels that are described by
the tube manufacturer as no longer applicable.
(f) [Reserved]
(g) Information to be provided to assemblers. Manufacturers of
components listed in paragraph (a)(1) of this section shall provide to
assemblers subject to paragraph (d) of this section and, upon request,
to others at a cost not to exceed the cost of publication and
distribution, instructions for assembly, installation, adjustment, and
testing of such components adequate to assure that the products will
comply with applicable provisions of this section and Sec. Sec.
1020.31, 1020.32, and 1020.33, when assembled, installed, adjusted, and
tested as directed. Such instructions shall include specifications of
other components compatible with that to be installed when compliance of
the system or subsystem depends on their compatibility. Such
specifications may describe pertinent physical characteristics of the
components and/or may list by manufacturer model number the components
which are compatible. For x-ray controls and generators manufactured
after May 3, 1994, manufacturers shall provide:
(1) A statement of the rated line voltage and the range of line-
voltage regulation for operation at maximum line current;
(2) A statement of the maximum line current of the x-ray system
based on the maximum input voltage and current characteristics of the
tube housing assembly compatible with rated output voltage and rated
output current characteristics of the x-ray control and associated high-
voltage generator. If the rated input voltage and current
characteristics of the tube housing assembly are not known by the
manufacturer of the x-ray control and associated high-voltage generator,
the manufacturer shall provide information necessary to allow the
assembler to determine the maximum line current for the particular tube
housing assembly(ies);
(3) A statement of the technique factors that constitute the maximum
line current condition described in paragraph (g)(2) of this section.
(h) Information to be provided to users. Manufacturers of x-ray
equipment shall provide to purchasers and, upon request, to others at a
cost not to exceed the cost of publication and distribution, manuals or
instruction sheets which shall include the following technical and
safety information:
(1) All x-ray equipment. For x-ray equipment to which this section
and Sec. Sec. 1020.31, 1020.32, and 1020.33 are applicable, there shall
be provided:
(i) Adequate instructions concerning any radiological safety
procedures and precautions which may be necessary because of unique
features of the equipment; and
(ii) A schedule of the maintenance necessary to keep the equipment
in compliance with this section and Sec. Sec. 1020.31, 1020.32, and
1020.33.
(2) Tube housing assemblies. For each tube housing assembly, there
shall be provided:
(i) Statements of the leakage technique factors for all combinations
of tube housing assemblies and beam-limiting devices for which the tube
housing assembly manufacturer states compatibility, the minimum
filtration permanently in the useful beam expressed as millimeters (mm)
of aluminum equivalent, and the peak tube potential at which the
aluminum equivalent was obtained;
(ii) Cooling curves for the anode and tube housing; and
(iii) Tube rating charts. If the tube is designed to operate from
different types of x-ray high-voltage generators (such as single-phase
self rectified, single-phase half-wave rectified, single-phase full-wave
rectified, 3-phase 6-pulse, 3-phase 12-pulse, constant potential,
capacitor energy storage) or under modes of operation such as alternate
focal spot sizes or speeds of anode rotation which affect its rating,
specific identification of the difference in ratings shall be noted.
(3) X-ray controls and generators. For the x-ray control and
associated x-ray high-voltage generator, there shall be provided:
(i) A statement of the rated line voltage and the range of line-
voltage regulation for operation at maximum line current;
(ii) A statement of the maximum line current of the x-ray system
based on the maximum input voltage and output current characteristics of
the tube housing assembly compatible with rated output voltage and rated
current characteristics of the x-ray control and associated high-voltage
generator. If the rated input voltage and current characteristics of the
tube housing assembly are not known by the manufacturer of the x-ray
control and associated high-voltage generator, the manufacturer shall
provide necessary information to allow the purchaser to determine the
maximum line current for his particular tube housing assembly(ies);
(iii) A statement of the technique factors that constitute the
maximum line current condition described in paragraph (h)(3)(ii) of this
section;
(iv) In the case of battery-powered generators, a specification of
the minimum state of charge necessary for proper operation;
(v) Generator rating and duty cycle;
(vi) A statement of the maximum deviation from the preindication
given by labeled technique factor control settings or indicators during
any radiographic or CT exposure where the equipment is connected to a
power supply as described in accordance with this paragraph. In the case
of fixed technique factors, the maximum deviation from the nominal fixed
value of each factor shall be stated;
(vii) A statement of the maximum deviation from the continuous
indication of x-ray tube potential and current during any fluoroscopic
exposure when the equipment is connected to a power supply as described
in accordance with this paragraph; and
(viii) A statement describing the measurement criteria for all
technique factors used in paragraphs (h)(3)(iii), (h)(3)(vi), and
(h)(3)(vii) of this section; for example, the beginning and endpoints of
exposure time measured with respect to a certain percentage of the
voltage waveform.
(4) Beam-limiting device. For each variable-aperture beam-limiting
device, there shall be provided;
(i) Leakage technique factors for all combinations of tube housing
assemblies and beam-limiting devices for which the beam-limiting device
manufacturer states compatibility; and
(ii) A statement including the minimum aluminum equivalent of that
part of the device through which the useful beam passes and including
the x-ray tube potential at which the aluminum equivalent was obtained.
When two or more filters are provided as part of the device, the
statement shall include the aluminum equivalent of each filter.
(5) Imaging system information. For x-ray systems manufactured on or
after June 10, 2006, that produce images using the fluoroscopic image
receptor, the following information shall be provided in a separate,
single section of the user's instruction manual or in a separate manual
devoted to this information:
(i) For each mode of operation, a description of the mode and
detailed instructions on how the mode is engaged and disengaged. The
description of the mode shall identify those technique factors and
system controls that are fixed or automatically adjusted by selection of
the mode of operation, including the manner in which the automatic
adjustment is controlled. This information shall include how the
operator can recognize which mode of operation has been selected prior
to initiation of x-ray production.
(ii) For each mode of operation, a descriptive example(s) of any
specific clinical procedure(s) or imaging task(s) for which the mode is
recommended or designed and how each mode should be used. Such
recommendations do not preclude other clinical uses.
(6) Displays of values of AKR and cumulative air kerma. For
fluoroscopic x-ray systems manufactured on or after June 10, 2006, the
following shall be provided:
(i) A schedule of maintenance for any system instrumentation
associated with the display of air kerma information necessary to
maintain the displays of AKR and cumulative air kerma within the limits
of allowed uncertainty specified by Sec. 1020.32(k)(6) and, if the
capability for user calibration of the display is provided, adequate
instructions for such calibration;
(ii) Identification of the distances along the beam axis:
(A) From the focal spot to the isocenter, and
(B) From the focal spot to the reference location to which displayed
values of AKR and cumulative air kerma refer according to Sec.
1020.32(k)(4);
(iii) A rationale for specification of a reference irradiation
location alternative to 15 cm from the isocenter toward the x-ray source
along the beam axis when such alternative specification is made
according to Sec. 1020.32(k)(4)(ii).
(i) [Reserved]
(j) Warning label. The control panel containing the main power
switch shall bear the warning statement, legible and accessible to view:
``Warning: This x-ray unit may be dangerous to patient and operator
unless safe exposure factors, operating instructions and maintenance
schedules are observed.''
(k) Leakage radiation from the diagnostic source assembly. The
leakage radiation from the diagnostic source assembly measured at a
distance of 1 meter in any direction from the source shall not exceed
0.88 milligray (mGy) air kerma (vice 100 milliroentgen (mR) exposure) in
1 hour when the x-ray tube is operated at the leakage technique factors.
If the maximum rated peak tube potential of the tube housing assembly is
greater than the maximum rated peak tube potential for the diagnostic
source assembly, positive means shall be provided to limit the maximum
x-ray tube potential to that of the diagnostic source assembly.
Compliance shall be determined by measurements averaged over an area of
100 square cm with no linear dimension greater than 20 cm.
(l) Radiation from components other than the diagnostic source
assembly. The radiation emitted by a component other than the diagnostic
source assembly shall not exceed an air kerma of 18 microGy (vice 2 mR
exposure) in 1 hour at 5 cm from any accessible surface of the component
when it is operated in an assembled x-ray system under any conditions
for which it was designed. Compliance shall be determined by
measurements averaged over an area of 100 square cm with no linear
dimension greater than 20 cm.
(m) Beam quality--(1) Half-value layer (HVL). The HVL of the useful
beam for a given x-ray tube potential shall not be less than the
appropriate value shown in table 1 in paragraph (m)(1) of this section
under the heading ``Specified Dental Systems,'' for any dental x-ray
system designed for use with intraoral image receptors and manufactured
after December 1, 1980; under the heading ``I--Other X-Ray Systems,''
for any dental x-ray system designed for use with intraoral image
receptors and manufactured before December 1, 1980, and all other x-ray
systems subject to this section and manufactured before June 10, 2006;
and under the heading ``II--Other X-Ray Systems,'' for all x-ray
systems, except dental x-ray systems designed for use with intraoral
image receptors, subject to this section and manufactured on or after
June 10, 2006. If it is necessary to determine such HVL at an x-ray tube
potential which is not listed in table 1 in paragraph (m)(1) of this
section, linear interpolation or extrapolation may be made. Positive
means\2\ shall be provided to ensure that at least the minimum
filtration needed to achieve the above beam quality requirements is in
the useful beam during each exposure. Table 1 follows:
---------------------------------------------------------------------------
\2\ In the case of a system, which is to be operated with more than
one thickness of filtration, this requirement can be met by a filter
interlocked with the kilovoltage selector which will prevent x-ray
emissions if the minimum required filtration is not in place.
Table 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
X-Ray Tube Voltage (kilovolt peak) Minimum HVL (mm of aluminum)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Measured Operating Specified Dental I--Other X-Ray II--Other X-Ray
Designed Operating Range Potential Systems\1\ Systems\2\ Systems\3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Below 51 30 1.5 0.3 0.3
40 1.5 0.4 0.4
50 1.5 0.5 0.5
51 to 70 51 1.5 1.2 1.3
60 1.5 1.3 1.5
70 1.5 1.5 1.8
Above 70 71 2.1 2.1 2.5
80 2.3 2.3 2.9
90 2.5 2.5 3.2
100 2.7 2.7 3.6
110 3.0 3.0 3.9
120 3.2 3.2 4.3
130 3.5 3.5 4.7
140 3.8 3.8 5.0
150 4.1 4.1 5.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Dental x-ray systems designed for use with intraoral image receptors and manufactured after December 1, 1980.
\2\ Dental x-ray systems designed for use with intraoral image receptors and manufactured before or on December 1, 1980, and all other x-ray systems
subject to this section and manufactured before June 10, 2006.
\3\ All x-ray systems, except dental x-ray systems designed for use with intraoral image receptors, subject to this section and manufactured on or after
June 10, 2006.
(2) Optional filtration. Fluoroscopic systems manufactured on or
after June 10, 2006, incorporating an x-ray tube(s) with a continuous
output of 1 kilowatt or more and an anode heat storage capacity of 1
million heat units or more shall provide the option of adding x-ray
filtration to the diagnostic source assembly in addition to the amount
needed to meet the HVL provisions of Sec. 1020.30(m)(1). The selection
of this additional x-ray filtration shall be either at the option of the
user or automatic as part of the selected mode of operation. A means of
indicating which combination of additional filtration is in the x-ray
beam shall be provided.
(3) Measuring compliance. For capacitor energy storage equipment,
compliance shall be determined with the maximum selectable quantity of
charge per exposure.
(n) Aluminum equivalent of material between patient and image
receptor. Except when used in a CT x-ray system, the aluminum equivalent
of each of the items listed in table 2 in paragraph (n) of this section,
which are used between the patient and image receptor, may not exceed
the indicated limits. Compliance shall be determined by x-ray
measurements made at a potential of 100 kilovolts peak and with an x-ray
beam that has an HVL specified in table 1 in paragraph (m)(1) of this
section for the potential. This requirement applies to front panel(s) of
cassette holders and film changers provided by the manufacturer for
patient support or for prevention of foreign object intrusions. It does
not apply to screens and their associated mechanical support panels or
grids. Table 2 follows:
Table 2
------------------------------------------------------------------------
Maximum Aluminum
Item Equivalent
(millimeters)
------------------------------------------------------------------------
1. Front panel(s) of cassette holders (total of all) 1.2
2. Front panel(s) of film changer (total of all) 1.2
3. Cradle 2.3
4. Tabletop, stationary, without articulated joints 1.2
5. Tabletop, movable, without articulated joint(s) 1.7
(including stationary subtop)
6. Tabletop, with radiolucent panel having one 1.7
articulated joint
7. Tabletop, with radiolucent panel having two or 2.3
more articulated joints
8. Tabletop, cantilevered 2.3
9. Tabletop, radiation therapy simulator 5.0
------------------------------------------------------------------------
(o) Battery charge indicator. On battery-powered generators, visual
means shall be provided on the control panel to indicate whether the
battery is in a state of charge adequate for proper operation.
(p) [Reserved]
(q) Modification of certified diagnostic x-ray components and
systems. (1) Diagnostic x-ray components and systems certified in
accordance with Sec. 1010.2 of this chapter shall not be modified such
that the component or system fails to comply with any applicable
provision of this chapter unless a variance in accordance with Sec.
1010.4 of this chapter or an exemption under section 534(a)(5) or 538(b)
of the Federal Food, Drug, and Cosmetic Act has been granted.
(2) The owner of a diagnostic x-ray system who uses the system in a
professional or commercial capacity may modify the system, provided the
modification does not result in the failure of the system or component
to comply with the applicable requirements of this section or of Sec.
1020.31, 1020.32, or 1020.33. The owner who causes such modification
need not submit the reports required by subpart B of part 1002 of this
chapter, provided the owner records the date and the details of the
modification in the system records and maintains this information, and
provided the modification of the x-ray system does not result in a
failure to comply with Sec. 1020.31, 1020.32, or 1020.33.
Sec. 1020.31 Radiographic equipment.
The provisions of this section apply to equipment for the recording
of images, except equipment involving use of an image intensifier or
computed tomography x-ray systems manufactured on or after November 28,
1984.
(a) Control and indication of technique factors--(1) Visual
indication. The technique factors to be used during an exposure shall be
indicated before the exposure begins, except when automatic exposure
controls are used, in which case the technique factors which are set
prior to the exposure shall be indicated. On equipment having fixed
technique factors, this requirement may be met by permanent markings.
Indication of technique factors shall be visible from the operator's
position except in the case of spot films made by the fluoroscopist.
(2) Timers. Means shall be provided to terminate the exposure at a
preset
time interval, a preset product of current and time, a preset number of
pulses, or a preset radiation exposure to the image receptor.
(i) Except during serial radiography, the operator shall be able to
terminate the exposure at any time during an exposure of greater than
one-half second. Except during panoramic dental radiography, termination
of exposure shall cause automatic resetting of the timer to its initial
setting or to zero. It shall not be possible to make an exposure when
the timer is set to a zero or off position if either position is
provided.
(ii) During serial radiography, the operator shall be able to
terminate the x-ray exposure(s) at any time, but means may be provided
to permit completion of any single exposure of the series in process.
(3) Automatic exposure controls. When an automatic exposure control
is provided:
(i) Indication shall be made on the control panel when this mode of
operation is selected;
(ii) When the x-ray tube potential is equal to or greater than 51
kilovolts peak (kVp), the minimum exposure time for field emission
equipment rated for pulsed operation shall be equal to or less than a
time interval equivalent to two pulses and the minimum exposure time for
all other equipment shall be equal to or less than 1/60 second or a time
interval required to deliver 5 milliamperes-seconds (mAs), whichever is
greater;
(iii) Either the product of peak x-ray tube potential, current, and
exposure time shall be limited to not more than 60 kilowatt-seconds
(kW's) per exposure or the product of x-ray tube current and exposure
time shall be limited to not more than 600 mAs per exposure, except when
the x-ray tube potential is less than 51 kVp, in which case the product
of x-ray tube current and exposure time shall be limited to not more
than 2,000 mAs per exposure; and
(iv) A visible signal shall indicate when an exposure has been
terminated at the limits described in paragraph (a)(3)(iii) of this
section, and manual resetting shall be required before further
automatically timed exposures can be made.
(4) Accuracy. Deviation of technique factors from indicated values
shall not exceed the limits given in the information provided in
accordance with Sec. 1020.30(h)(3);
(b) Reproducibility. The following requirements shall apply when the
equipment is operated on an adequate power supply as specified by the
manufacturer in accordance with the requirements of Sec. 1020.30(h)(3);
(1) Coefficient of variation. For any specific combination of
selected technique factors, the estimated coefficient of variation of
radiation exposures shall be no greater than 0.05.
(2) Measuring compliance. Determination of compliance shall be based
on 10 consecutive measurements taken within a time period of 1 hour.
Equipment manufactured after September 5, 1978, shall be subject to the
additional requirement that all variable controls for technique factors
shall be adjusted to alternate settings and reset to the test setting
after each measurement. The percent line-voltage regulation shall be
determined for each measurement. All values for percent line-voltage
regulation shall be within <plus-minus<ls-thn-eq>1 of the mean value for
all measurements. For equipment having automatic exposure controls,
compliance shall be determined with a sufficient thickness of
attenuating material in the useful beam such that the technique factors
can be adjusted to provide individual exposures of a minimum of 12
pulses on field emission equipment rated for pulsed operation or no less
than one-tenth second per exposure on all other equipment.
(c) Linearity. The following requirements apply when the equipment
is operated on a power supply as specified by the manufacturer in
accordance with the requirements of Sec. 1020.30(h)(3) for any fixed x-
ray tube potential within the range of 40 percent to 100 percent of the
maximum rated.
(1) Equipment having independent selection of x-ray tube current
(mA). The average ratios of exposure to the indicated milliampere-
seconds product (C/kg/mAs (or mR/mAs)) obtained at any two consecutive
tube current settings shall not differ by more than 0.10 times their
sum. This is: [verbar]X<INF>1</INF>-
X<INF>2</INF>[verbar]<=0.10(X<INF>1</INF>+X<INF>2</INF>); where
X<INF>1</INF> and X<INF>2</INF> are the average C/kg/
mAs (or mR/mAs) values obtained at each of two consecutive tube current
settings or at two settings differing by no more than a factor of 2
where the tube current selection is continuous.
(2) Equipment having selection of x-ray tube current-exposure time
product (mAs). For equipment manufactured after May 3, 1994 the average
ratios of exposure to the indicated milliampere-seconds product (C/kg/
mAs (or mR/mAs)) obtained at any two consecutive mAs selector settings
shall not differ by more than 0.10 times their sum. This is:
[verbar]X<INF>1</INF>-
X<INF>2</INF>[verbar]<=0.10(X<INF>1</INF>+X<INF>2</INF>); where
X<INF>1</INF> and X<INF>2</INF> are the average C/kg/mAs (or mR/mAs)
values obtained at each of two consecutive mAs selector settings or at
two settings differing by no more than a factor of 2 where the mAs
selector provides continuous selection.
(3) Measuring compliance. Determination of compliance will be based
on 10 exposures, made within <plus-minus<ls-thn-eq>1 hour, at each of
the two settings. These two settings may include any two focal spot
sizes except where one is equal to or less than 0.45 millimeters and the
other is greater than 0.45 millimeters. For purposes of this
requirement, focal spot size is the focal spot size specified by the x-
ray tube manufacturer. The percent line-voltage regulation shall be
determined for each measurement. All values for percent line-voltage
regulation at any one combination of technique factors shall be within
<greek-i>1 of the mean value for all measurements at these technique
factors.
(d) Field limitation and alignment for mobile, portable, and
stationary general purpose x-ray systems. Except when spot-film devices
or special attachments for mammography are in service, mobile, portable,
and stationary general purpose radiographic x-ray systems shall meet the
following requirements:
(1) Variable x-ray field limitation. A means for stepless adjustment
of the size of the x-ray field shall be provided. Each dimension of the
minimum field size at an SID of 100 centimeters shall be equal to or
less than 5 centimeters.
(2) Visual definition. (i) Means for visually defining the perimeter
of the x-ray field shall be provided. The total misalignment of the
edges of the visually defined field with the respective edges of the x-
ray field along either the length or width of the visually defined field
shall not exceed 2 percent of the distance from the source to the center
of the visually defined field when the surface upon which it appears is
perpendicular to the axis of the x-ray beam.
(ii) When a light localizer is used to define the x-ray field, it
shall provide an average illuminance of not less than 160 lux (15
footcandles) at 100 centimeters or at the maximum SID, whichever is
less. The average illuminance shall be based upon measurements made in
the approximate center of each quadrant of the light field. Radiation
therapy simulation systems are exempt from this requirement.
(iii) The edge of the light field at 100 centimeters or at the
maximum SID, whichever is less, shall have a contrast ratio, corrected
for ambient lighting, of not less than 4 in the case of beam-limiting
devices designed for use on stationary equipment, and a contrast ratio
of not less than 3 in the case of beam-limiting devices designed for use
on mobile and portable equipment. The contrast ratio is defined as
I<INF>1</INF> I<INF>2</INF>, where I<INF>1</INF> is the illuminance 3
millimeters from the edge of the light field toward the center of the
field; and I<INF>2</INF> is the illuminance 3 millimeters from the edge
of the light field away from the center of the field. Compliance shall
be determined with a measuring aperture of 1 millimeter.
(e) Field indication and alignment on stationary general purpose x-
ray equipment. Except when spot-film devices or special attachments for
mammography are in service, stationary general purpose x-ray systems
shall meet the following requirements in addition to those prescribed in
paragraph (d) of this section:
(1) Means shall be provided to indicate when the axis of the x-ray
beam is perpendicular to the plane of the image receptor, to align the
center of the x-ray field with respect to the center of the image
receptor to within 2 percent of the SID, and to indicate the SID to
within 2 percent;
(2) The beam-limiting device shall numerically indicate the field
size in the plane of the image receptor to which it is adjusted;
(3) Indication of field size dimensions and SID's shall be specified
in centimeters and/or inches and shall be such that aperture adjustments
result in x-ray field dimensions in the plane of the image receptor
which correspond to those indicated by the beam-limiting device to
within 2 percent of the SID when the beam axis is indicated to be
perpendicular to the plane of the image receptor; and
(4) Compliance measurements will be made at discrete SID's and image
receptor dimensions in common clinical use (such as SID's of 100, 150,
and 200 centimeters and/or 36, 40, 48, and 72 inches and nominal image
receptor dimensions of 13, 18, 24, 30, 35, 40, and 43 centimeters and/or
5, 7, 8, 9, 10, 11, 12, 14, and 17 inches) or at any other specific
dimensions at which the beam-limiting device or its associated
diagnostic x-ray system is uniquely designed to operate.
(f) Field limitation on radiographic x-ray equipment other than
general purpose radiographic systems--(1) Equipment for use with
intraoral image receptors. Radiographic equipment designed for use with
an intraoral image receptor shall be provided with means to limit the x-
ray beam such that:
(i) If the minimum source-to-skin distance (SSD) is 18 centimeters
or more, the x-ray field at the minimum SSD shall be containable in a
circle having a diameter of no more than 7 centimeters; and
(ii) If the minimum SSD is less than 18 centimeters, the x-ray field
at the minimum SSD shall be containable in a circle having a diameter of
no more than 6 centimeters.
(2) X-ray systems designed for one image receptor size. Radiographic
equipment designed for only one image receptor size at a fixed SID shall
be provided with means to limit the field at the plane of the image
receptor to dimensions no greater than those of the image receptor, and
to align the center of the x-ray field with the center of the image
receptor to within 2 percent of the SID or shall be provided with means
to both size and align the x-ray field such that the x-ray field at the
plane of the image receptor does not extend beyond any edge of the image
receptor.
(3) Systems designed for mammography. (i) Mammographic beam-limiting
devices manufactured after September 30, 1999, shall be provided with
means to limit the useful beam such that the x-ray field at the plane of
the image receptor does not extend beyond any edge of the image receptor
by more than 2 percent of the SID. This requirement can be met with a
system that performs as prescribed in paragraphs (f)(4)(i), (f)(4)(ii),
and (f)(4)(iii) of this section. For systems that allow changes in the
SID, the SID indication specified in paragraphs (f)(4)(ii) and
(f)(4)(iii) of this section shall be the maximum SID for which the beam-
limiting device or aperture is designed.
(ii) Each image receptor support device intended for installation on
a system designed for mammography shall have clear and permanent
markings to indicate the maximum image receptor size for which it is
designed.
(4) Other x-ray systems. Radiographic systems not specifically
covered in paragraphs (d), (e), (f)(2), (f)(3), and (h) of this section
and systems covered in paragraph (f)(1) of this section, which are also
designed for use with extraoral image receptors and when used with an
extraoral image receptor, shall be provided with means to limit the x-
ray field in the plane of the image receptor so that such field does not
exceed each dimension of the image receptor by more than 2 percent of
the SID, when the axis of the x-ray beam is perpendicular to the plane
of the image receptor. In addition, means shall be provided to align the
center of the x-ray field with the center of the image receptor to
within 2 percent of the SID, or means shall be provided to both size and
align the x-ray field such that the x-ray field at the plane of the
image receptor does not extend beyond any edge of the image receptor.
These requirements may be met with:
(i) A system which performs in accordance with paragraphs (d) and
(e) of this section; or when alignment means are also provided, may be
met with either;
(ii) An assortment of removable, fixed-aperture, beam-limiting
devices sufficient to meet the requirement for each combination of image
receptor
size and SID for which the unit is designed. Each such device shall have
clear and permanent markings to indicate the image receptor size and SID
for which it is designed; or
(iii) A beam-limiting device having multiple fixed apertures
sufficient to meet the requirement for each combination of image
receptor size and SID for which the unit is designed. Permanent, clearly
legible markings shall indicate the image receptor size and SID for
which each aperture is designed and shall indicate which aperture is in
position for use.
(g) Positive beam limitation (PBL). The requirements of this
paragraph shall apply to radiographic systems which contain PBL.
(1) Field size. When a PBL system is provided, it shall prevent x-
ray production when:
(i) Either the length or width of the x-ray field in the plane of
the image receptor differs from the corresponding image receptor
dimension by more than 3 percent of the SID; or
(ii) The sum of the length and width differences as stated in
paragraph (g)(1)(i) of this section without regard to sign exceeds 4
percent of the SID.
(iii) The beam limiting device is at an SID for which PBL is not
designed for sizing.
(2) Conditions for PBL. When provided, the PBL system shall function
as described in paragraph (g)(1) of this section whenever all the
following conditions are met:
(i) The image receptor is inserted into a permanently mounted
cassette holder;
(ii) The image receptor length and width are less than 50
centimeters;
(iii) The x-ray beam axis is within <plus-minus<ls-thn-eq>3 degrees
of vertical and the SID is 90 centimeters to 130 centimeters inclusive;
or the x-ray beam axis is within <plus-minus<ls-thn-eq>3 degrees of
horizontal and the SID is 90 centimeters to 205 centimeters inclusive;
(iv) The x-ray beam axis is perpendicular to the plane of the image
receptor to within <plus-minus<ls-thn-eq>3 degrees; and
(v) Neither tomographic nor stereoscopic radiography is being
performed.
(3) Measuring compliance. Compliance with the requirements of
paragraph (g)(1) of this section shall be determined when the equipment
indicates that the beam axis is perpendicular to the plane of the image
receptor and the provisions of paragraph (g)(2) of this section are met.
Compliance shall be determined no sooner than 5 seconds after insertion
of the image receptor.
(4) Operator initiated undersizing. The PBL system shall be capable
of operation such that, at the discretion of the operator, the size of
the field may be made smaller than the size of the image receptor
through stepless adjustment of the field size. Each dimension of the
minimum field size at an SID of 100 centimeters shall be equal to or
less than 5 centimeters. Return to PBL function as described in
paragraph (g)(1) of this section shall occur automatically upon any
change of image receptor size or SID.
(5) Override of PBL. A capability may be provided for overriding PBL
in case of system failure and for servicing the system. This override
may be for all SID's and image receptor sizes. A key shall be required
for any override capability that is accessible to the operator. It shall
not be possible to remove the key while PBL is overridden. Each such key
switch or key shall be clearly and durably labeled as follows:
For X-ray Field Limitation System Failure
The override capability is considered accessible to the operator if
it is referenced in the operator's manual or in other material intended
for the operator or if its location is such that the operator would
consider it part of the operational controls.
(h) Field limitation and alignment for spot-film devices. The
following requirements shall apply to spot-film devices, except when the
spot-film device is provided for use with a radiation therapy simulation
system:
(1) Means shall be provided between the source and the patient for
adjustment of the x-ray field size in the plane of the image receptor to
the size of that portion of the image receptor which has been selected
on the spot-film selector. Such adjustment shall be accomplished
automatically when the x-ray field size in the plane of the image
receptor is greater than the selected portion of the image receptor. If
the x-ray field size is less than the size
of the selected portion of the image receptor, the field size shall not
open automatically to the size of the selected portion of the image
receptor unless the operator has selected that mode of operation.
(2) Neither the length nor the width of the x-ray field in the plane
of the image receptor shall differ from the corresponding dimensions of
the selected portion of the image receptor by more than 3 percent of the
SID when adjusted for full coverage of the selected portion of the image
receptor. The sum, without regard to sign, of the length and width
differences shall not exceed 4 percent of the SID. On spot-film devices
manufactured after February 25, 1978, if the angle between the plane of
the image receptor and beam axis is variable, means shall be provided to
indicate when the axis of the x-ray beam is perpendicular to the plane
of the image receptor, and compliance shall be determined with the beam
axis indicated to be perpendicular to the plane of the image receptor.
(3) The center of the x-ray field in the plane of the image receptor
shall be aligned with the center of the selected portion of the image
receptor to within 2 percent of the SID.
(4) Means shall be provided to reduce the x-ray field size in the
plane of the image receptor to a size smaller than the selected portion
of the image receptor such that:
(i) For spot-film devices used on fixed-SID fluoroscopic systems
which are not required to, and do not provide stepless adjustment of the
x-ray field, the minimum field size, at the greatest SID, does not
exceed 125 square centimeters; or
(ii) For spot-film devices used on fluoroscopic systems that have a
variable SID and/or stepless adjustment of the field size, the minimum
field size, at the greatest SID, shall be containable in a square of 5
centimeters by 5 centimeters.
(5) A capability may be provided for overriding the automatic x-ray
field size adjustment in case of system failure. If it is so provided, a
signal visible at the fluoroscopist's position shall indicate whenever
the automatic x-ray field size adjustment override is engaged. Each such
system failure override switch shall be clearly labeled as follows:
For X-ray Field Limitation System Failure
(i) Source-skin distance--(1) X-ray systems designed for use with an
intraoral image receptor shall be provided with means to limit the
source-skin distance to not less than:
(i) Eighteen centimeters if operable above 50 kVp; or
(ii) Ten centimeters if not operable above 50 kVp.
(2) Mobile and portable x-ray systems other than dental shall be
provided with means to limit the source-skin distance to not less than
30 centimeters.
(j) Beam-on indicators. The x-ray control shall provide visual
indication whenever x-rays are produced. In addition, a signal audible
to the operator shall indicate that the exposure has terminated.
(k) Multiple tubes. Where two or more radiographic tubes are
controlled by one exposure switch, the tube or tubes which have been
selected shall be clearly indicated before initiation of the exposure.
This indication shall be both on the x-ray control and at or near the
tube housing assembly which has been selected.
(l) Radiation from capacitor energy storage equipment. Radiation
emitted from the x-ray tube shall not exceed:
(1) 8.6x10<SUP>-9</SUP> C/kg (0.03 mR) in 1 minute at 5 centimeters
from any accessible surface of the diagnostic source assembly, with the
beam-limiting device fully open, the system fully charged, and the
exposure switch, timer, or any discharge mechanism not activated.
Compliance shall be determined by measurements averaged over an area of
100 square centimeters, with no linear dimension greater than 20
centimeters; and
(2) 2.58x10<SUP>-5</SUP> C/kg (100 mR) in 1 hour at 100 centimeters
from the x-ray source, with the beam-limiting device fully open, when
the system is discharged through the x-ray tube either manually or
automatically by use of a discharge switch or deactivation of the
input power. Compliance shall be determined by measurements of the
maximum exposure per discharge multiplied by the total number of
discharges in 1 hour (duty cycle). The measurements shall be averaged
over an area of 100 square centimeters with no linear dimension greater
than 20 centimeters.
(m) Primary protective barrier for mammography x-ray systems. For
mammography x-ray systems manufactured after September 30, 1999:
(1) At any SID where exposures can be made, the image receptor
support device shall provide a primary protective barrier that
intercepts the cross section of the useful beam along every direction
except at the chest wall edge.
(2) The x-ray tube shall not permit exposure unless the appropriate
barrier is in place to intercept the useful beam as required in
paragraph (m)(1) of this section.
(3) The transmission of the useful beam through the primary
protective barrier shall be limited such that the exposure 5 centimeters
from any accessible surface beyond the plane of the primary protective
barrier does not exceed 2.58x10<SUP>-8</SUP> C/kg (0.1 mR) for each
activation of the tube.
(4) Compliance for transmission shall be determined with the x-ray
system operated at the minimum SID for which it is designed, at the
maximum rated peak tube potential, at the maximum rated product of x-ray
tube current and exposure time (mAs) for the maximum rated peak tube
potential, and by measurements averaged over an area of 100 square
centimeters with no linear dimension greater than 20 centimeters. The
sensitive volume of the radiation measuring instrument shall not be
positioned beyond the edge of the primary protective barrier along the
chest wall side.
[58 FR 26401, May 3, 1993; 58 FR 31067, May 28, 1993, as amended at 64
FR 35927, July 2, 1999]
Effective Date Note: At 70 FR 34036, June 10, 2005, Sec. 1020.31
was revised, effective June 10, 2006. For the convenience of the user,
the revised text is set forth as follows:
Sec. 1020.31 Radiographic equipment.
The provisions of this section apply to equipment for radiography,
except equipment for fluoroscopic imaging or for recording images from
the fluoroscopic image receptor, or computed tomography x-ray systems
manufactured on or after November 29, 1984.
(a) Control and indication of technique factors--(1) Visual
indication. The technique factors to be used during an exposure shall be
indicated before the exposure begins, except when automatic exposure
controls are used, in which case the technique factors which are set
prior to the exposure shall be indicated. On equipment having fixed
technique factors, this requirement may be met by permanent markings.
Indication of technique factors shall be visible from the operator's
position except in the case of spot films made by the fluoroscopist.
(2) Timers. Means shall be provided to terminate the exposure at a
preset time interval, a preset product of current and time, a preset
number of pulses, or a preset radiation exposure to the image receptor.
(i) Except during serial radiography, the operator shall be able to
terminate the exposure at any time during an exposure of greater than
one-half second. Except during panoramic dental radiography, termination
of exposure shall cause automatic resetting of the timer to its initial
setting or to zero. It shall not be possible to make an exposure when
the timer is set to a zero or off position if either position is
provided.
(ii) During serial radiography, the operator shall be able to
terminate the x-ray exposure(s) at any time, but means may be provided
to permit completion of any single exposure of the series in process.
(3) Automatic exposure controls. When an automatic exposure control
is provided:
(i) Indication shall be made on the control panel when this mode of
operation is selected;
(ii) When the x-ray tube potential is equal to or greater than 51
kilovolts peak (kVp), the minimum exposure time for field emission
equipment rated for pulsed operation shall be equal to or less than a
time interval equivalent to two pulses and the minimum exposure time for
all other equipment shall be equal to or less than 1/60 second or a time
interval required to deliver 5 milliampere-seconds (mAs), whichever is
greater;
(iii) Either the product of peak x-ray tube potential, current, and
exposure time shall be limited to not more than 60 kilowatt-seconds
(kWs) per exposure or the product of x-ray tube current and exposure
time shall be limited to not more than 600 mAs per exposure, except when
the x-ray tube potential is less than 51 kVp, in which case the product
of x-ray tube current and exposure time shall be limited to not more
than 2,000 mAs per exposure; and
(iv) A visible signal shall indicate when an exposure has been
terminated at the limits described in paragraph (a)(3)(iii) of this
section, and manual resetting shall be required before further
automatically timed exposures can be made.
(4) Accuracy. Deviation of technique factors from indicated values
shall not exceed the limits given in the information provided in
accordance with Sec. 1020.30(h)(3).
(b) Reproducibility. The following requirements shall apply when the
equipment is operated on an adequate power supply as specified by the
manufacturer in accordance with the requirements of Sec. 1020.30(h)(3):
(1) Coefficient of variation. For any specific combination of
selected technique factors, the estimated coefficient of variation of
the air kerma shall be no greater than 0.05.
(2) Measuring compliance. Determination of compliance shall be based
on 10 consecutive measurements taken within a time period of 1 hour.
Equipment manufactured after September 5, 1978, shall be subject to the
additional requirement that all variable controls for technique factors
shall be adjusted to alternate settings and reset to the test setting
after each measurement. The percent line-voltage regulation shall be
determined for each measurement. All values for percent line-voltage
regulation shall be within <plus-minus<ls-thn-eq>1 of the mean value for
all measurements. For equipment having automatic exposure controls,
compliance shall be determined with a sufficient thickness of
attenuating material in the useful beam such that the technique factors
can be adjusted to provide individual exposures of a minimum of 12
pulses on field emission equipment rated for pulsed operation or no less
than one-tenth second per exposure on all other equipment.
(c) Linearity. The following requirements apply when the equipment
is operated on a power supply as specified by the manufacturer in
accordance with the requirements of Sec. 1020.30(h)(3) for any fixed x-
ray tube potential within the range of 40 percent to 100 percent of the
maximum rated.
(1) Equipment having independent selection of x-ray tube current
(mA). The average ratios of air kerma to the indicated milliampere-
seconds product (mGy/mAs) obtained at any two consecutive tube current
settings shall not differ by more than 0.10 times their sum. This is:
[bond]X<INF>1</INF> - X<INF>2</INF>[bond] <= 0.10(X<INF>1</INF> +
X<INF>2</INF>); where X<INF>1</INF> and X<INF>2</INF> are the average
mGy/mAs values obtained at each of two consecutive mAs selector settings
or at two settings differing by no more than a factor of 2 where the mAs
selector provides continuous selection.
(2) Equipment having selection of x-ray tube current-exposure time
product (mAs). For equipment manufactured after May 3, 1994, the average
ratios of air kerma to the indicated milliampere-seconds product (mGy/
mAs) obtained at any two consecutive mAs selector settings shall not
differ by more than 0.10 times their sum. This is: [bond]X<INF>1</INF> -
X<INF>2</INF>[bond] <= 0.10 (X<INF>1</INF> + X<INF>2</INF>); where
X<INF>1</INF> and X<INF>2</INF> are the average mGy/mAs values obtained
at each of two consecutive mAs selector settings or at two settings
differing by no more than a factor of 2 where the mAs selector provides
continuous selection.
(3) Measuring compliance. Determination of compliance will be based
on 10 exposures, made within 1 hour, at each of the two settings. These
two settings may include any two focal spot sizes except where one is
equal to or less than 0.45 mm and the other is greater than 0.45 mm. For
purposes of this requirement, focal spot size is the focal spot size
specified by the x-ray tube manufacturer. The percent line-voltage
regulation shall be determined for each measurement. All values for
percent line-voltage regulation at any one combination of technique
factors shall be within <plus-minus<ls-thn-eq>1 of the mean value for
all measurements at these technique factors.
(d) Field limitation and alignment for mobile, portable, and
stationary general purpose x-ray systems. Except when spot-film devices
are in service, mobile, portable, and stationary general purpose
radiographic x-ray systems shall meet the following requirements:
(1) Variable x-ray field limitation. A means for stepless adjustment
of the size of the x-ray field shall be provided. Each dimension of the
minimum field size at an SID of 100 centimeters (cm) shall be equal to
or less than 5 cm.
(2) Visual definition. (i) Means for visually defining the perimeter
of the x-ray field shall be provided. The total misalignment of the
edges of the visually defined field with the respective edges of the x-
ray field along either the length or width of the visually defined field
shall not exceed 2 percent of the distance from the source to the center
of the visually defined field when the surface upon which it appears is
perpendicular to the axis of the x-ray beam.
(ii) When a light localizer is used to define the x-ray field, it
shall provide an average illuminance of not less than 160 lux (15
footcandles) at 100 cm or at the maximum SID, whichever is less. The
average illuminance shall be based on measurements made in the
approximate center of each quadrant of the light field. Radiation
therapy simulation systems are exempt from this requirement.
(iii) The edge of the light field at 100 cm or at the maximum SID,
whichever is less, shall have a contrast ratio, corrected for ambient
lighting, of not less than 4 in the case of beam-limiting devices
designed for use on stationary equipment, and a contrast ratio of not
less than 3 in the case of beam-limiting devices designed for use on
mobile and portable equipment. The contrast ratio is defined as
I<INF>1</INF>/I<INF>2</INF>, where I<INF>1</INF> is the illuminance 3 mm
from the edge of the light field toward the center of the field; and
I<INF>2</INF> is the illuminance 3 mm from the edge of the light field
away from the center of the field. Compliance shall be determined with a
measuring aperture of 1 mm.
(e) Field indication and alignment on stationary general purpose x-
ray equipment. Except when spot-film devices are in service, stationary
general purpose x-ray systems shall meet the following requirements in
addition to those prescribed in paragraph (d) of this section:
(1) Means shall be provided to indicate when the axis of the x-ray
beam is perpendicular to the plane of the image receptor, to align the
center of the x-ray field with respect to the center of the image
receptor to within 2 percent of the SID, and to indicate the SID to
within 2 percent;
(2) The beam-limiting device shall numerically indicate the field
size in the plane of the image receptor to which it is adjusted;
(3) Indication of field size dimensions and SIDs shall be specified
in centimeters and/or inches and shall be such that aperture adjustments
result in x-ray field dimensions in the plane of the image receptor
which correspond to those indicated by the beam-limiting device to
within 2 percent of the SID when the beam axis is indicated to be
perpendicular to the plane of the image receptor; and
(4) Compliance measurements will be made at discrete SIDs and image
receptor dimensions in common clinical use (such as SIDs of 100, 150,
and 200 cm and/or 36, 40, 48, and 72 inches and nominal image receptor
dimensions of 13, 18, 24, 30, 35, 40, and 43 cm and/or 5, 7, 8, 9, 10,
11, 12, 14, and 17 inches) or at any other specific dimensions at which
the beam-limiting device or its associated diagnostic x-ray system is
uniquely designed to operate.
(f) Field limitation on radiographic x-ray equipment other than
general purpose radiographic systems--(1) Equipment for use with
intraoral image receptors. Radiographic equipment designed for use with
an intraoral image receptor shall be provided with means to limit the x-
ray beam such that:
(i) If the minimum source-to-skin distance (SSD) is 18 cm or more,
the x-ray field at the minimum SSD shall be containable in a circle
having a diameter of no more than 7 cm; and
(ii) If the minimum SSD is less than 18 cm, the x-ray field at the
minimum SSD shall be containable in a circle having a diameter of no
more than 6 cm.
(2) X-ray systems designed for one image receptor size. Radiographic
equipment designed for only one image receptor size at a fixed SID shall
be provided with means to limit the field at the plane of the image
receptor to dimensions no greater than those of the image receptor, and
to align the center of the x-ray field with the center of the image
receptor to within 2 percent of the SID, or shall be provided with means
to both size and align the x-ray field such that the x-ray field at the
plane of the image receptor does not extend beyond any edge of the image
receptor.
(3) Systems designed for mammography--(i) Radiographic systems
designed only for mammography and general purpose radiography systems,
when special attachments for mammography are in service, manufactured on
or after November 1, 1977, and before September 30, 1999, shall be
provided with means to limit the useful beam such that the x-ray field
at the plane of the image receptor does not extend beyond any edge of
the image receptor at any designated SID except the edge of the image
receptor designed to be adjacent to the chest wall where the x-ray field
may not extend beyond this edge by more than 2 percent of the SID. This
requirement can be met with a system that performs as prescribed in
paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of this section. When
the beam-limiting device and image receptor support device are designed
to be used to immobilize the breast during a mammographic procedure and
the SID may vary, the SID indication specified in paragraphs (f)(4)(ii)
and (f)(4)(iii) of this section shall be the maximum SID for which the
beam-limiting device or aperture is designed.
(ii) Mammographic beam-limiting devices manufactured on or after
September 30, 1999, shall be provided with a means to limit the useful
beam such that the x-ray field at the plane of the image receptor does
not extend beyond any edge of the image receptor by more than 2 percent
of the SID. This requirement can be met with a system that performs as
prescribed in paragraphs (f)(4)(i), (f)(4)(ii), and (f)(4)(iii) of this
section. For systems that allow changes in the SID, the SID indication
specified in paragraphs (f)(4)(ii) and (f)(4)(iii) of this section shall
be the maximum SID for which the beam-limiting device or aperture is
designed.
(iii) Each image receptor support device manufactured on or after
November 1, 1977, intended for installation on a system designed for
mammography shall have clear and permanent markings to indicate the
maximum image receptor size for which it is designed.
(4) Other x-ray systems. Radiographic systems not specifically
covered in paragraphs (d), (e), (f)(2), (f)(3), and (h) of this section
and systems covered in paragraph (f)(1) of this section, which are also
designed for use with extraoral image receptors and when used with an
extraoral image receptor, shall be provided with means to limit the x-
ray field in the plane of the image receptor so that such field does not
exceed each dimension of the image receptor by more than 2 percent of
the SID, when the axis of the x-ray beam is perpendicular to the plane
of the image receptor. In addition, means shall be provided to align the
center of the x-ray field with the center of the image receptor to
within 2 percent of the SID, or means shall be provided to both size and
align the x-ray field such that the x-ray field at the plane of
the image receptor does not extend beyond any edge of the image
receptor. These requirements may be met with:
(i) A system which performs in accordance with paragraphs (d) and
(e) of this section; or when alignment means are also provided, may be
met with either;
(ii) An assortment of removable, fixed-aperture, beam-limiting
devices sufficient to meet the requirement for each combination of image
receptor size and SID for which the unit is designed. Each such device
shall have clear and permanent markings to indicate the image receptor
size and SID for which it is designed; or
(iii) A beam-limiting device having multiple fixed apertures
sufficient to meet the requirement for each combination of image
receptor size and SID for which the unit is designed. Permanent, clearly
legible markings shall indicate the image receptor size and SID for
which each aperture is designed and shall indicate which aperture is in
position for use.
(g) Positive beam limitation (PBL). The requirements of this
paragraph shall apply to radiographic systems which contain PBL.
(1) Field size. When a PBL system is provided, it shall prevent x-
ray production when:
(i) Either the length or width of the x-ray field in the plane of
the image receptor differs from the corresponding image receptor
dimension by more than 3 percent of the SID; or
(ii) The sum of the length and width differences as stated in
paragraph (g)(1)(i) of this section without regard to sign exceeds 4
percent of the SID.
(iii) The beam limiting device is at an SID for which PBL is not
designed for sizing.
(2) Conditions for PBL. When provided, the PBL system shall function
as described in paragraph (g)(1) of this section whenever all the
following conditions are met:
(i) The image receptor is inserted into a permanently mounted
cassette holder;
(ii) The image receptor length and width are less than 50 cm;
(iii) The x-ray beam axis is within <plus-minus<ls-thn-eq>3 degrees
of vertical and the SID is 90 cm to 130 cm inclusive; or the x-ray beam
axis is within <plus-minus<ls-thn-eq>3 degrees of horizontal and the SID
is 90 cm to 205 cm inclusive;
(iv) The x-ray beam axis is perpendicular to the plane of the image
receptor to within <plus-minus<ls-thn-eq>3 degrees; and
(v) Neither tomographic nor stereoscopic radiography is being
performed.
(3) Measuring compliance. Compliance with the requirements of
paragraph (g)(1) of this section shall be determined when the equipment
indicates that the beam axis is perpendicular to the plane of the image
receptor and the provisions of paragraph (g)(2) of this section are met.
Compliance shall be determined no sooner than 5 seconds after insertion
of the image receptor.
(4) Operator initiated undersizing. The PBL system shall be capable
of operation such that, at the discretion of the operator, the size of
the field may be made smaller than the size of the image receptor
through stepless adjustment of the field size. Each dimension of the
minimum field size at an SID of 100 cm shall be equal to or less than 5
cm. Return to PBL function as described in paragraph (g)(1) of this
section shall occur automatically upon any change of image receptor size
or SID.
(5) Override of PBL. A capability may be provided for overriding PBL
in case of system failure and for servicing the system. This override
may be for all SIDs and image receptor sizes. A key shall be required
for any override capability that is accessible to the operator. It shall
not be possible to remove the key while PBL is overridden. Each such key
switch or key shall be clearly and durably labeled as follows:
For X-ray Field Limitation System Failure
The override capability is considered accessible to the operator if it
is referenced in the operator's manual or in other material intended for
the operator or if its location is such that the operator would consider
it part of the operational controls.
(h) Field limitation and alignment for spot-film devices. The
following requirements shall apply to spot-film devices, except when the
spot-film device is provided for use with a radiation therapy simulation
system:
(1) Means shall be provided between the source and the patient for
adjustment of the x-ray field size in the plane of the image receptor to
the size of that portion of the image receptor which has been selected
on the spot-film selector. Such adjustment shall be accomplished
automatically when the x-ray field size in the plane of the image
receptor is greater than the selected portion of the image receptor. If
the x-ray field size is less than the size of the selected portion of
the image receptor, the field size shall not open automatically to the
size of the selected portion of the image receptor unless the operator
has selected that mode of operation.
(2) Neither the length nor the width of the x-ray field in the plane
of the image receptor shall differ from the corresponding dimensions of
the selected portion of the image receptor by more than 3 percent of the
SID when adjusted for full coverage of the selected portion of the image
receptor. The sum, without regard to sign, of the length and width
differences shall not exceed 4 percent of the SID. On spot-film devices
manufactured after February 25, 1978, if the angle between the plane of
the image receptor and beam axis is variable, means shall be provided to
indicate when the axis of the x-ray
beam is perpendicular to the plane of the image receptor, and compliance
shall be determined with the beam axis indicated to be perpendicular to
the plane of the image receptor.
(3) The center of the x-ray field in the plane of the image receptor
shall be aligned with the center of the selected portion of the image
receptor to within 2 percent of the SID.
(4) Means shall be provided to reduce the x-ray field size in the
plane of the image receptor to a size smaller than the selected portion
of the image receptor such that:
(i) For spot-film devices used on fixed-SID fluoroscopic systems
which are not required to, and do not provide stepless adjustment of the
x-ray field, the minimum field size, at the greatest SID, does not
exceed 125 square cm; or
(ii) For spot-film devices used on fluoroscopic systems that have a
variable SID and/or stepless adjustment of the field size, the minimum
field size, at the greatest SID, shall be containable in a square of 5
cm by 5 cm.
(5) A capability may be provided for overriding the automatic x-ray
field size adjustment in case of system failure. If it is so provided, a
signal visible at the fluoroscopist's position shall indicate whenever
the automatic x-ray field size adjustment override is engaged. Each such
system failure override switch shall be clearly labeled as follows:
For X-ray Field Limitation System Failure
(i) Source-skin distance--(1) X-ray systems designed for use with an
intraoral image receptor shall be provided with means to limit the
source-skin distance to not less than:
(i) Eighteen cm if operable above 50 kVp; or
(ii) Ten cm if not operable above 50 kVp.
(2) Mobile and portable x-ray systems other than dental shall be
provided with means to limit the source-skin distance to not less than
30 cm.
(j) Beam-on indicators. The x-ray control shall provide visual
indication whenever x-rays are produced. In addition, a signal audible
to the operator shall indicate that the exposure has terminated.
(k) Multiple tubes. Where two or more radiographic tubes are
controlled by one exposure switch, the tube or tubes which have been
selected shall be clearly indicated before initiation of the exposure.
This indication shall be both on the x-ray control and at or near the
tube housing assembly which has been selected.
(l) Radiation from capacitor energy storage equipment. Radiation
emitted from the x-ray tube shall not exceed:
(1) An air kerma of 0.26 microGy (vice 0.03 mR exposure) in 1 minute
at 5 cm from any accessible surface of the diagnostic source assembly,
with the beam-limiting device fully open, the system fully charged, and
the exposure switch, timer, or any discharge mechanism not activated.
Compliance shall be determined by measurements averaged over an area of
100 square cm, with no linear dimension greater than 20 cm; and
(2) An air kerma of 0.88 mGy (vice 100 mR exposure) in 1 hour at 100
cm from the x-ray source, with the beam-limiting device fully open, when
the system is discharged through the x-ray tube either manually or
automatically by use of a discharge switch or deactivation of the input
power. Compliance shall be determined by measurements of the maximum air
kerma per discharge multiplied by the total number of discharges in 1
hour (duty cycle). The measurements shall be averaged over an area of
100 square cm with no linear dimension greater than 20 cm.
(m) Primary protective barrier for mammography x-ray systems--(1)
For x-ray systems manufactured after September 5, 1978, and before
September 30, 1999, which are designed only for mammography, the
transmission of the primary beam through any image receptor support
provided with the system shall be limited such that the air kerma 5 cm
from any accessible surface beyond the plane of the image receptor
supporting device does not exceed 0.88 microGy (vice 0.1 mR exposure)
for each activation of the tube.
(2) For mammographic x-ray systems manufactured on or after
September 30, 1999:
(i) At any SID where exposures can be made, the image receptor
support device shall provide a primary protective barrier that
intercepts the cross section of the useful beam along every direction
except at the chest wall edge.
(ii) The x-ray system shall not permit exposure unless the
appropriate barrier is in place to intercept the useful beam as required
in paragraph (m)(2)(i) of this section.
(iii) The transmission of the useful beam through the primary
protective barrier shall be limited such that the air kerma 5 cm from
any accessible surface beyond the plane of the primary protective
barrier does not exceed 0.88 microGy (vice 0.1 mR exposure) for each
activation of the tube.
(3) Compliance with the requirements of paragraphs (m)(1) and
(m)(2)(iii) of this section for transmission shall be determined with
the x-ray system operated at the minimum SID for which it is designed,
at the maximum rated peak tube potential, at the maximum rated product
of x-ray tube current and exposure time (mAs) for the maximum rated peak
tube potential, and by measurements averaged over an area of 100 square
cm with no linear dimension greater than 20 cm. The sensitive volume of
the radiation measuring instrument shall not be positioned beyond the
edge of the primary protective barrier along the chest wall side.
70 FR 34036, June 10, 2005]
Sec. 1020.32 Fluoroscopic equipment.
The provisions of this section apply to equipment for fluoroscopy
and for the recording of images through an image intensifier except
computed tomography x-ray systems manufactured on or after November 29,
1984.
(a) Primary protective barrier--(1) Limitation of useful beam. The
fluoroscopic imaging assembly shall be provided with a primary
protective barrier which intercepts the entire cross section of the
useful beam at any SID. The x-ray tube used for fluoroscopy shall not
produce x-rays unless the barrier is in position to intercept the entire
useful beam. The exposure rate due to transmission through the barrier
with the attenuation block in the useful beam combined with radiation
from the image intensifier if provided, shall not exceed
3.34x10<SUP>-3</SUP> percent of the entrance exposure rate, at a
distance of 10 centimeters from any accessible surface of the
fluoroscopic imaging assembly beyond the plane of the image receptor.
Radiation therapy simulation systems shall be exempt from this
requirement provided the systems are intended only for remote control
operation and the manufacturer sets forth instructions for assemblers
with respect to control location as part of the information required in
Sec. 1020.30(g). Additionally, the manufacturer shall provide to users,
pursuant to Sec. 1020.30(h)(1)(i), precautions concerning the
importance of remote control operation.
(2) Measuring compliance. The entrance exposure rate shall be
measured in accordance with paragraph (d) of this section. The exposure
rate due to transmission through the primary barrier combined with
radiation from the image intensifier shall be determined by measurements
averaged over an area of 100 square centimeters with no linear dimension
greater than 20 centimeters. If the source is below the tabletop, the
measurement shall be made with the input surface of the fluoroscopic
imaging assembly positioned 30 centimeters above the tabletop. If the
source is above the tabletop and the SID is variable, the measurement
shall be made with the end of the beam-limiting device or spacer as
close to the tabletop as it can be placed, provided that it shall not be
closer than 30 centimeters. Movable grids and compression devices shall
be removed from the useful beam during the measurement. For all
measurements, the attenuation block shall be positioned in the useful
beam 10 centimeters from the point of measurement of entrance exposure
rate and between this point and the input surface of the fluoroscopic
imaging assembly.
(b) Field limitation--(1) Nonimage-intensified fluoroscopy. (i) The
x-ray field produced by nonimage-intensified fluoroscopic equipment
shall not extend beyond the entire visible area of the image receptor.
Means shall be provided for stepless adjustment of the field size. The
minimum field size, at the greatest SID, shall be containable in a
square of 5 centimeters by 5 centimeters.
(ii) For equipment manufactured after February 25, 1978, when the
angle between the image receptor and the beam axis of the x-ray beam is
variable, means shall be provided to indicate when the axis of the x-ray
beam is perpendicular to the plane of the image receptor. Compliance
with paragraph (b)(1)(i) of this section shall be determined with the
beam axis indicated to be perpendicular to the plane of the image
receptor.
(2) Image-intensified fluoroscopy. (i) For image-intensified
fluoroscopic equipment other than radiation therapy simulation systems,
neither the length nor the width of the x-ray field in the plane of the
image receptor shall exceed that of the visible area of the image
receptor by more than 3 percent of the SID. The sum of the excess length
and the excess width shall be no greater than 4 percent of the SID.
(ii) For rectangular x-ray fields used with circular image
receptors, the error in alignment shall be determined along the length
and width dimensions of the x-ray field which pass through the center of
the visible area of the image receptor.
(iii) For equipment manufactured after February 25, 1978, when the
angle between the image receptor and beam axis is variable, means shall
be provided to indicate when the axis of the x-ray beam is perpendicular
to the
plane of the image receptor. Compliance with paragraph (b)(2)(i) of this
section shall be determined with the beam axis indicated to be
perpendicular to the plane of the image receptor.
(iv) Means shall be provided to permit further limitation of the
field. Beam-limiting devices manufactured after May 22, 1979, and
incorporated in equipment with a variable SID and/or the capability of a
visible area of greater than 300 square centimeters shall be provided
with means for stepless adjustment of the x-ray field. Equipment with a
fixed SID and the capability of a visible area of no greater than 300
square centimeters shall be provided with either stepless adjustment of
the x-ray field or with a means to further limit the x-ray field size at
the plane of the image receptor to 125 square centimeters or less.
Stepless adjustment shall, at the greatest SID, provide continuous field
sizes from the maximum obtainable to a field size containable in a
square of 5 centimeters by 5 centimeters.
(3) If the fluoroscopic x-ray field size is adjusted automatically
as the SID or image receptor size is changed, a capability may be
provided for overriding the automatic adjustment in case of system
failure. If it is so provided, a signal visible at the fluoroscopist's
position shall indicate whenever the automatic field adjustment is
overridden. Each such system failure override switch shall be clearly
labeled as follows:
For X-ray Field Limitation System Failure
(c) Activation of tube. X-ray production in the fluoroscopic mode
shall be controlled by a device which requires continuous pressure by
the operator for the entire time of any exposure. When recording serial
fluoroscopic images, the operator shall be able to terminate the x-ray
exposure(s) at any time, but means may be provided to permit completion
of any single exposure of the series in process.
(d) Entrance exposure rates. For fluoroscopic equipment manufactured
before May 19, 1995, the following requirements apply:
(1) Equipment with automatic exposure rate control (AERC).
Fluoroscopic equipment that is provided with AERC shall not be operable
at any combination of tube potential and current that will result in an
exposure rate in excess of 2.58x10<SUP>-3</SUP> coulomb per kilogram (C/
kg) per minute (10 roentgens per minute (10 R/min)) at the point where
the center of the useful beam enters the patient, except:
(i) During recording of fluoroscopic images, or
(ii) When an optional high-level control is provided. When so
provided, the equipment shall not be operable at any combination of tube
potential and current that will result in an exposure rate in excess of
1.29x10<SUP>-3</SUP> C/kg per minute (5 R/min) at the point where the
center of the useful beam enters the patient, unless the high-level
control is activated. Special means of activation of high-level controls
shall be required. The high-level control shall be operable only when
continuous manual activation is provided by the operator. A continuous
signal audible to the fluoroscopist shall indicate that the high-level
control is being employed.
(2) Equipment without AERC (manual mode). Fluoroscopic equipment
that is not provided with AERC shall not be operable at any combination
of tube potential and current that will result in an exposure rate in
excess of 1.29x10<SUP>-3</SUP> C/kg per minute (5 R/min) at the point
where the center of the useful beam enters the patient, except:
(i) During recording of fluoroscopic images, or
(ii) When an optional high-level control is activated. Special means
of activation of high-level controls shall be required. The high-level
control shall be operable only when continuous manual activation is
provided by the operator. A continuous signal audible to the
fluoroscopist shall indicate that the high-level control is being
employed.
(3) Equipment with both an AERC mode and a manual mode. Fluoroscopic
equipment that is provided with both an AERC mode and a manual mode
shall not be operable at any combination of tube potential and current
that will result in an exposure rate in excess of
2.58x10<SUP>-3</SUP> C/kg per minute (10 R/min) in either mode at the
point where the center of the useful beam enters the patient except:
(i) During recording of fluoroscopic images, or
(ii) When the mode or modes have an optional high-level control, in
which case that mode or modes shall not be operable at any combination
of tube potential and current that will result in an exposure rate in
excess of 1.29x10<SUP>-3</SUP> C/kg per minute (5 R/min) at the point
where the center of the useful beam enters the patient, unless the high-
level control is activated. Special means of activation of high-level
controls shall be required. The high-level control shall be operable
only when continuous manual activation is provided by the operator. A
continuous signal audible to the fluoroscopist shall indicate that the
high-level is being employed.
(4) Measuring compliance. Compliance with paragraph (d) of this
section shall be determined as follows:
(i) If the source is below the x-ray table, the exposure rate shall
be measured at 1 centimeter above the tabletop or cradle.
(ii) If the source is above the x-ray table, the exposure rate shall
be measured at 30 centimeters above the tabletop with the end of the
beam-limiting device or spacer positioned as closely as possible to the
point of measurement.
(iii) In a C-arm type of fluoroscope, the exposure rate shall be
measured at 30 centimeters from the input surface of the fluoroscopic
imaging assembly, with the source positioned at any available SID,
provided that the end of the beam-limiting device or spacer is no closer
than 30 centimeters from the input surface of the imaging assembly.
(iv) In a lateral type of fluoroscope, the exposure rate shall be
measured at a point 15 centimeters from the centerline of the x-ray
table and in the direction of the x-ray source with the end of the beam-
limiting device or spacer positioned as closely as possible to the point
of measurement. If the tabletop is movable, it shall be positioned as
closely as possible to the lateral x-ray source, with the end of the
beam-limiting device or spacer no closer than 15 centimeters to the
centerline of the x-ray table.
(5) Exemptions. Fluoroscopic radiation therapy simulation systems
are exempt from the requirements set forth in paragraph (d) of this
section.
(e) Entrance exposure rate limits. For fluoroscopic equipment
manufactured on and after May 19, 1995, the following requirements
apply:
(1) Fluoroscopic equipment operable at any combination of tube
potential and current that results in an exposure rate greater than
1.29x10<SUP>-3</SUP> C/kg per minute (5 R/min) at the point where the
center of the useful beam enters the patient shall be equipped with
AERC. Provision for manual selection of technique factors may be
provided.
(2) Fluoroscopic equipment shall not be operable at any combination
of tube potential and current that will result in an exposure rate in
excess of 2.58x10<SUP>-3</SUP> C/kg per minute (10 R/min) at the point
where the center of the useful beam enters the patient except:
(i) During the recording of images from an x-ray image-intensifier
tube using photographic film or a video camera when the x-ray source is
operated in a pulsed mode.
(ii) When an optional high-level control is activated. When the
high-level control is activated, the equipment shall not be operable at
any combination of tube potential and current that will result in an
exposure rate in excess of 5.16x10<SUP>-3</SUP> C/kg per minute (20 R/
min) at the point where the center of the useful beam enters the
patient. Special means of activation of high-level controls shall be
required. The high-level control shall only be operable when continuous
manual activation is provided by the operator. A continuous signal
audible to the fluoroscopist shall indicate that the high-level control
is being employed.
(3) Measuring compliance. Compliance with paragraph (e) of this
section shall be determined as follows:
(i) If the source is below the x-ray table, the exposure rate shall
be measured at 1 centimeter above the tabletop or cradle.
(ii) If the source is above the x-ray table, the exposure rate shall
be measured at 30 centimeters above the tabletop with the end of the
beam-limiting
device or spacer positioned as closely as possible to the point of
measurement.
(iii) In a C-arm type of fluoroscope, the exposure rate shall be
measured at 30 centimeters from the input surface of the fluoroscopic
imaging assembly, with the source positioned at any available SID,
provided that the end of the beam-limiting device or spacer is no closer
than 30 centimeters from the input surface of the fluoroscopic imaging
assembly.
(iv) In a lateral type of fluoroscope, the exposure rate shall be
measured at a point 15 centimeters from the centerline of the x-ray
table and in the direction of the x-ray source with the end of the beam-
limiting device or spacer positioned as closely as possible to the point
of measurement. If the tabletop is movable, it shall be positioned as
closely as possible to the lateral x-ray source, with the end of the
beam-limiting device or spacer no closer than 15 centimeters to the
centerline of the x-ray table.
(4) Exemptions. Fluoroscopic radiation therapy simulation systems
are exempt from the requirements set forth in paragraph (e) of this
section.
(f) Indication of potential and current. During fluoroscopy and
cinefluorography, x-ray tube potential and current shall be continuously
indicated. Deviation of x-ray tube potential and current from the
indicated values shall not exceed the maximum deviation as stated by the
manufacturer in accordance with Sec. 1020.30(h)(3).
(g) Source-skin distance. Means shall be provided to limit the
source-skin distance to not less than 38 centimeters on stationary
fluoroscopes and to not less than 30 centimeters on mobile and portable
fluoroscopes. In addition, for image-intensified fluoroscopes intended
for specific surgical application that would be prohibited at the
source-skin distances specified in this paragraph, provisions may be
made for operation at shorter source-skin distances but in no case less
than 20 centimeters. When provided, the manufacturer must set forth
precautions with respect to the optional means of spacing, in addition
to other information as required in Sec. 1020.30(h).
(h) Fluoroscopic timer. Means shall be provided to preset the
cumulative on-time of the fluoroscopic tube. The maximum cumulative time
of the timing device shall not exceed 5 minutes without resetting. A
signal audible to the fluoroscopist shall indicate the completion of any
preset cumulative on-time. Such signal shall continue to sound while x-
rays are produced until the timing device is reset. As an alternative to
the requirements of this paragraph, radiation therapy simulation systems
may be provided with a means to indicate the total cumulative exposure
time during which x-rays were produced, and which is capable of being
reset between x-ray examinations.
(i) Mobile and portable fluoroscopes. In addition to the foregoing
requirements of this section, mobile and portable fluoroscopes shall
provide intensified imaging.
[58 FR 26404, May 3, 1993, as amended at 59 FR 26404, May 19, 1994]
Effective Date Note: At 70 FR 34039, June 10, 2005, Sec. 1020.32
was revised, effective June 10, 2006. For the convenience of the user,
the revised text is set forth as follows:
Sec. 1020.32 Fluoroscopic equipment.
The provisions of this section apply to equipment for fluoroscopic
imaging or for recording images from the fluoroscopic image receptor,
except computed tomography x-ray systems manufactured on or after
November 29, 1984.
(a) Primary protective barrier--(1) Limitation of useful beam. The
fluoroscopic imaging assembly shall be provided with a primary
protective barrier which intercepts the entire cross section of the
useful beam at any SID. The x-ray tube used for fluoroscopy shall not
produce x-rays unless the barrier is in position to intercept the entire
useful beam. The AKR due to transmission through the barrier with the
attenuation block in the useful beam combined with radiation from the
fluoroscopic image receptor shall not exceed 3.34x10<SUP>-3</SUP>
percent of the entrance AKR, at a distance of 10 cm from any accessible
surface of the fluoroscopic imaging assembly beyond the plane of the
image receptor. Radiation therapy simulation systems shall be exempt
from this requirement provided the systems are intended only for remote
control operation and the manufacturer sets forth instructions for
assemblers with respect to control location as part of the information
required in Sec. 1020.30(g). Additionally, the manufacturer shall
provide to users, under
Sec. 1020.30(h)(1)(i), precautions concerning the importance of remote
control operation.
(2) Measuring compliance. The AKR shall be measured in accordance
with paragraph (d) of this section. The AKR due to transmission through
the primary barrier combined with radiation from the fluoroscopic image
receptor shall be determined by measurements averaged over an area of
100 square cm with no linear dimension greater than 20 cm. If the source
is below the tabletop, the measurement shall be made with the input
surface of the fluoroscopic imaging assembly positioned 30 cm above the
tabletop. If the source is above the tabletop and the SID is variable,
the measurement shall be made with the end of the beam-limiting device
or spacer as close to the tabletop as it can be placed, provided that it
shall not be closer than 30 cm. Movable grids and compression devices
shall be removed from the useful beam during the measurement. For all
measurements, the attenuation block shall be positioned in the useful
beam 10 cm from the point of measurement of entrance AKR and between
this point and the input surface of the fluoroscopic imaging assembly.
(b) Field limitation--(1) Angulation. For fluoroscopic equipment
manufactured after February 25, 1978, when the angle between the image
receptor and the beam axis of the x-ray beam is variable, means shall be
provided to indicate when the axis of the x-ray beam is perpendicular to
the plane of the image receptor. Compliance with paragraphs (b)(4) and
(b)(5) of this section shall be determined with the beam axis indicated
to be perpendicular to the plane of the image receptor.
(2) Further means for limitation. Means shall be provided to permit
further limitation of the x-ray field to sizes smaller than the limits
of paragraphs (b)(4) and (b)(5). Beam-limiting devices manufactured
after May 22, 1979, and incorporated in equipment with a variable SID
and/or the capability of a visible area of greater than 300 square cm,
shall be provided with means for stepless adjustment of the x-ray field.
Equipment with a fixed SID and the capability of a visible area of no
greater than 300 square cm shall be provided with either stepless
adjustment of the x-ray field or with a means to further limit the x-ray
field size at the plane of the image receptor to 125 square cm or less.
Stepless adjustment shall, at the greatest SID, provide continuous field
sizes from the maximum obtainable to a field size containable in a
square of 5 cm by 5 cm. This paragraph does not apply to non-image-
intensified fluoroscopy.
(3) Non-image-intensified fluoroscopy. The x-ray field produced by
non-image-intensified fluoroscopic equipment shall not extend beyond the
entire visible area of the image receptor. Means shall be provided for
stepless adjustment of field size. The minimum field size, at the
greatest SID, shall be containable in a square of 5 cm by 5 cm.
(4) Fluoroscopy and radiography using the fluoroscopic imaging
assembly with inherently circular image receptors. (i) For fluoroscopic
equipment manufactured before June 10, 2006, other than radiation
therapy simulation systems, the following applies:
(A) Neither the length nor the width of the x-ray field in the plane
of the image receptor shall exceed that of the visible area of the image
receptor by more than 3 percent of the SID. The sum of the excess length
and the excess width shall be no greater than 4 percent of the SID.
(B) For rectangular x-ray fields used with circular image receptors,
the error in alignment shall be determined along the length and width
dimensions of the x-ray field which pass through the center of the
visible area of the image receptor.
(ii) For fluoroscopic equipment manufactured on or after June 10,
2006, other than radiation therapy simulation systems, the maximum area
of the x-ray field in the plane of the image receptor shall conform with
one of the following requirements:
(A) When any linear dimension of the visible area of the image
receptor measured through the center of the visible area is less than or
equal to 34 cm in any direction, at least 80 percent of the area of the
x-ray field overlaps the visible area of the image receptor, or
(B) When any linear dimension of the visible area of the image
receptor measured through the center of the visible area is greater than
34 cm in any direction, the x-ray field measured along the direction of
greatest misalignment with the visible area of the image receptor does
not extend beyond the edge of the visible area of the image receptor by
more than 2 cm.
(5) Fluoroscopy and radiography using the fluoroscopic imaging
assembly with inherently rectangular image receptors. For x-ray systems
manufactured on or after June 10, 2006, the following applies:
(i) Neither the length nor the width of the x-ray field in the plane
of the image receptor shall exceed that of the visible area of the image
receptor by more than 3 percent of the SID. The sum of the excess length
and the excess width shall be no greater than 4 percent of the SID.
(ii) The error in alignment shall be determined along the length and
width dimensions of the x-ray field which pass through the center of the
visible area of the image receptor.
(6) Override capability. If the fluoroscopic x-ray field size is
adjusted automatically as the SID or image receptor size is changed, a
capability may be provided for overriding the automatic adjustment in
case of system failure. If it is so provided, a signal visible at the
fluoroscopist's position shall indicate
whenever the automatic field adjustment is overridden. Each such system
failure override switch shall be clearly labeled as follows:
For X-ray Field Limitation System Failure
(c) Activation of tube. X-ray production in the fluoroscopic mode
shall be controlled by a device which requires continuous pressure by
the operator for the entire time of any exposure. When recording serial
radiographic images from the fluoroscopic image receptor, the operator
shall be able to terminate the x-ray exposure(s) at any time, but means
may be provided to permit completion of any single exposure of the
series in process.
(d) Air kerma rates. For fluoroscopic equipment, the following
requirements apply:
(1) Fluoroscopic equipment manufactured before May 19, 1995--(i)
Equipment provided with automatic exposure rate control (AERC) shall not
be operable at any combination of tube potential and current that will
result in an AKR in excess of 88 mGy per minute (vice 10 R/min exposure
rate) at the measurement point specified in Sec. 1020.32(d)(3), except
as specified in Sec. 1020.32(d)(1)(v).
(ii) Equipment provided without AERC shall not be operable at any
combination of tube potential and current that will result in an AKR in
excess of 44 mGy per minute (vice 5 R/min exposure rate) at the
measurement point specified in Sec. 1020.32(d)(3), except as specified
in Sec. 1020.32(d)(1)(v).
(iii) Equipment provided with both an AERC mode and a manual mode
shall not be operable at any combination of tube potential and current
that will result in an AKR in excess of 88 mGy per minute (vice 10 R/min
exposure rate) in either mode at the measurement point specified in
Sec. 1020.32(d)(3), except as specified in Sec. 1020.32(d)(1)(v).
(iv) Equipment may be modified in accordance with Sec. 1020.30(q)
to comply with Sec. 1020.32(d)(2). When the equipment is modified, it
shall bear a label indicating the date of the modification and the
statement:
Modified to comply with 21 CFR 1020.32(h)(2).
(v) Exceptions:
(A) During recording of fluoroscopic images, or
(B) When a mode of operation has an optional high-level control, in
which case that mode shall not be operable at any combination of tube
potential and current that will result in an AKR in excess of the rates
specified in Sec. 1020.32(d)(1)(i), (d)(1)(ii), or (d)(1)(iii) at the
measurement point specified in Sec. 1020.32(d)(3), unless the high-
level control is activated. Special means of activation of high-level
controls shall be required. The high-level control shall be operable
only when continuous manual activation is provided by the operator. A
continuous signal audible to the fluoroscopist shall indicate that the
high-level control is being employed.
(2) Fluoroscopic equipment manufactured on or after May 19, 1995--
(i) Shall be equipped with AERC if operable at any combination of tube
potential and current that results in an AKR greater than 44 mGy per
minute (vice 5 R/min exposure rate) at the measurement point specified
in Sec. 1020.32(d)(3). Provision for manual selection of technique
factors may be provided.
(ii) Shall not be operable at any combination of tube potential and
current that will result in an AKR in excess of 88 mGy per minute (vice
10 R/min exposure rate) at the measurement point specified in Sec.
1020.32(d)(3), except as specified in Sec. 1020.32(d)(2)(iii):
(iii) Exceptions:
(A) For equipment manufactured prior to June 10, 2006, during the
recording of images from a fluoroscopic image receptor using
photographic film or a video camera when the x-ray source is operated in
a pulsed mode.
(B) For equipment manufactured on or after June 10, 2006, during the
recording of images from the fluoroscopic image receptor for the purpose
of providing the user with a recorded image(s) after termination of the
exposure. Such recording does not include images resulting from a last-
image-hold feature that are not recorded.
(C) When a mode of operation has an optional high-level control and
the control is activated, in which case the equipment shall not be
operable at any combination of tube potential and current that will
result in an AKR in excess of 176 mGy per minute (vice 20 R/min exposure
rate) at the measurement point specified in Sec. 1020.32(d)(3). Special
means of activation of high-level controls shall be required. The high-
level control shall be operable only when continuous manual activation
is provided by the operator. A continuous signal audible to the
fluoroscopist shall indicate that the high-level control is being
employed.
(3) Measuring compliance. Compliance with paragraph (d) of this
section shall be determined as follows:
(i) If the source is below the x-ray table, the AKR shall be
measured at 1 cm above the tabletop or cradle.
(ii) If the source is above the x-ray table, the AKR shall be
measured at 30 cm above the tabletop with the end of the beam-limiting
device or spacer positioned as closely as possible to the point of
measurement.
(iii) In a C-arm type of fluoroscope, the AKR shall be measured at
30 cm from the input surface of the fluoroscopic imaging assembly, with
the source positioned at any available SID, provided that the end of the
beam-limiting device or spacer is no closer than 30 cm from the input
surface of the fluoroscopic imaging assembly.
(iv) In a C-arm type of fluoroscope having an SID less than 45 cm,
the AKR shall be measured at the minimum SSD.
(v) In a lateral type of fluoroscope, the air kerma rate shall be
measured at a point 15 cm from the centerline of the x-ray table and in
the direction of the x-ray source with the end of the beam-limiting
device or spacer positioned as closely as possible to the point of
measurement. If the tabletop is movable, it shall be positioned as
closely as possible to the lateral x-ray source, with the end of the
beam-limiting device or spacer no closer than 15 cm to the centerline of
the x-ray table.
(4) Exemptions. Fluoroscopic radiation therapy simulation systems
are exempt from the requirements set forth in paragraph (d) of this
section.
(e) [Reserved]
(f) Indication of potential and current. During fluoroscopy and
cinefluorography, x-ray tube potential and current shall be continuously
indicated. Deviation of x-ray tube potential and current from the
indicated values shall not exceed the maximum deviation as stated by the
manufacturer in accordance with Sec. 1020.30(h)(3).
(g) Source-skin distance. (1) Means shall be provided to limit the
source-skin distance to not less than 38 cm on stationary fluoroscopes
and to not less than 30 cm on mobile and portable fluoroscopes. In
addition, for fluoroscopes intended for specific surgical application
that would be prohibited at the source-skin distances specified in this
paragraph, provisions may be made for operation at shorter source-skin
distances but in no case less than 20 cm. When provided, the
manufacturer must set forth precautions with respect to the optional
means of spacing, in addition to other information as required in Sec.
1020.30(h).
(2) For stationary, mobile, or portable C-arm fluoroscopic systems
manufactured on or after June 10, 2006, having a maximum source-image
receptor distance of less than 45 cm, means shall be provided to limit
the source-skin distance to not less than 19 cm. Such systems shall be
labeled for extremity use only. In addition, for those systems intended
for specific surgical application that would be prohibited at the
source-skin distances specified in this paragraph, provisions may be
made for operation at shorter source-skin distances but in no case less
than 10 cm. When provided, the manufacturer must set forth precautions
with respect to the optional means of spacing, in addition to other
information as required in Sec. 1020.30(h).
(h) Fluoroscopic irradiation time, display, and signal. (1)(i)
Fluoroscopic equipment manufactured before June 10, 2006, shall be
provided with means to preset the cumulative irradiation time of the
fluoroscopic tube. The maximum cumulative time of the timing device
shall not exceed 5 minutes without resetting. A signal audible to the
fluoroscopist shall indicate the completion of any preset cumulative
irradiation-time. Such signal shall continue to sound while x-rays are
produced until the timing device is reset. Fluoroscopic equipment may be
modified in accordance with Sec. 1020.30(q) to comply with the
requirements of Sec. 1020.32(h)(2). When the equipment is modified, it
shall bear a label indicating the statement:
Modified to comply with 21 CFR 1020.32(h)(2).
(ii) As an alternative to the requirements of this paragraph,
radiation therapy simulation systems may be provided with a means to
indicate the total cumulative exposure time during which x-rays were
produced, and which is capable of being reset between x-ray
examinations.
(2) For x-ray controls manufactured on or after June 10, 2006, there
shall be provided for each fluoroscopic tube:
(i) A display of the fluoroscopic irradiation time at the
fluoroscopist's working position. This display shall function
independently of the audible signal described in Sec.
1020.32(h)(2)(ii). The following requirements apply:
(A) When the x-ray tube is activated, the fluoroscopic irradiation
time in minutes and tenths of minutes shall be continuously displayed
and updated at least once every 6 seconds.
(B) The fluoroscopic irradiation time shall also be displayed within
6 seconds of termination of an exposure and remain displayed until
reset.
(C) Means shall be provided to reset the display to zero prior to
the beginning of a new examination or procedure.
(ii) A signal audible to the fluoroscopist shall sound for each
passage of 5 minutes of fluoroscopic irradiation time during an
examination or procedure. The signal shall sound until manually reset
or, if automatically reset, for at least 2 second.
(i) Mobile and portable fluoroscopes. In addition to the other
requirements of this section, mobile and portable fluoroscopes shall
provide an image receptor incorporating more than a simple fluorescent
screen.
(j) Display of last-image-hold (LIH). Fluoroscopic equipment
manufactured on or after June 10, 2006, shall be equipped with means to
display LIH image following termination of the fluoroscopic exposure.
(1) For an LIH image obtained by retaining pretermination
fluoroscopic images, if the number of images and method of combining
images are selectable by the user, the selection shall be indicated
prior to initiation of the fluoroscopic exposure.
(2) For an LIH image obtained by initiating a separate radiographic-
like exposure at the termination of fluoroscopic imaging, the techniques
factors for the LIH image shall be selectable prior to the fluoroscopic
exposure, and the combination selected shall be indicated prior to
initiation of the fluoroscopic exposure.
(3) Means shall be provided to clearly indicate to the user whether
a displayed image is the LIH radiograph or fluoroscopy. Display of the
LIH radiograph shall be replaced by the fluoroscopic image concurrently
with re-initiation of fluoroscopic exposure, unless separate displays
are provided for the LIH radiograph and fluoroscopic images.
(4) The predetermined or selectable options for producing the LIH
radiograph shall be described in the information required by Sec.
1020.30(h). The information shall include a description of any technique
factors applicable for the selected option and the impact of the
selectable options on image characteristics and the magnitude of
radiation emissions.
(k) Displays of values of AKR and cumulative air kerma. Fluoroscopic
equipment manufactured on or after June 10, 2006, shall display at the
fluoroscopist's working position the AKR and cumulative air kerma. The
following requirements apply for each x-ray tube used during an
examination or procedure:
(1) When the x-ray tube is activated and the number of images
produced per unit time is greater than six images per second, the AKR in
mGy/min shall be continuously displayed and updated at least once every
second.
(2) The cumulative air kerma in units of mGy shall be displayed
either within 5 seconds of termination of an exposure or displayed
continuously and updated at least once every 5 seconds.
(3) The display of the AKR shall be clearly distinguishable from the
display of the cumulative air kerma.
(4) The AKR and cumulative air kerma shall represent the value for
conditions of free-in-air irradiation at one of the following reference
locations specified according to the type of fluoroscope. The reference
location shall be identified and described specifically in the
information provided to users according to Sec. 1020.30(h)(6)(iii).
(i) For fluoroscopes with x-ray source below the x-ray table, x-ray
source above the table, or of lateral type, the reference locations
shall be the respective locations specified in Sec. 1020.32(d)(3)(i),
(d)(3)(ii), or (d)(3)(v) for measuring compliance with air-kerma rate
limits.
(ii) For C-arm fluoroscopes, the reference location shall be 15 cm
from the isocenter toward the x-ray source along the beam axis.
Alternatively, the reference location shall be at a point specified by
the manufacturer to represent the location of the intersection of the x-
ray beam with the patient's skin.
(5) Means shall be provided to reset to zero the display of
cumulative air kerma prior to the commencement of a new examination or
procedure.
(6) The displayed AKR and cumulative air kerma shall not deviate
from the actual values by more than <plus-minus<ls-thn-eq>35 percent
over the range of 6 mGy/min and 100 mGy to the maximum indication of AKR
and cumulative air kerma, respectively. Compliance shall be determined
with an irradiation time greater than 3 seconds.
Return to Top
Sec. 1020.33 Computed tomography (CT) equipment.
(a) Applicability. (1) The provisions of this section, except for
paragraphs (b), (c)(1), and (c)(2) are applicable as specified herein to
CT x-ray systems manufactured or remanufactured on or after September 3,
1985.
(2) The provisions of paragraphs (b), (c)(1), and (c)(2) are
applicable to CT x-ray systems manufactured or remanufactured on or
after November 29, 1984.
(b) Definitions. As used in this section, the following definitions
apply:
(1) Computed tomography dose index (CTDI) means the integral of the
dose profile along a line perpendicular to the tomographic plane divided
by the product of the nominal tomographic section thickness and the
number of tomograms produced in a single scan; that is:
[GRAPHIC] [TIFF OMITTED] TC01AP93.003
where:
z=position along a line perpendicular to the tomographic plane.
D(z)=Dose at position z.
T=Nominal tomographic section thickness.
n=Number of tomograms produced in a single scan.
This definition assumes that the dose profile is centered around z=0 and
that, for a multiple tomogram system, the scan increment between
adjacent scans is nT.
(2) Contrast scale means the change in linear attenuation
coefficient per CT number relative to water; that is:
[GRAPHIC] [TIFF OMITTED] TC01AP93.000
where:
[mu]<INF>w</INF>=Linear attenuation coefficient of water.
[mu]<INF>x</INF>=Linear attenuation coefficient of material of interest.
(CT)<INF>w</INF>=CT number of water.
(CT)<INF>x</INF>=CT number of material of interest.
(3) CT conditions of operation means all selectable parameters
governing the operation of a CT x-ray system including nominal
tomographic section thickness, filtration, and the technique factors as
defined in Sec. 1020.30(b)(36).
(4) CT number means the number used to represent the x-ray
attenuation associated with each elemental area of the CT image.
(5) [Reserved]
(6) CT dosimetry phantom means the phantom used for determination of
the dose delivered by a CT x-ray system. The phantom shall be a right
circular cylinder of polymethl-methacrylate of density 1.19<plus-
minus<ls-thn-eq>0.01 grams per cubic centimeter. The phantom shall be at
least 14 centimeters in length and shall have diameters of 32.0
centimeters for testing any CT system designed to image any section of
the body (whole body scanners) and 16.0 centimeters for any system
designed to image the head (head scanners) or for any whole body scanner
operated in the head scanning mode. The phantom shall provide means for
the placement of a dosimeter(s) along its axis of rotation and along a
line parallel to the axis of rotation 1.0 centimeter from the outer
surface and within the phantom. Means for the placement of a
dosimeter(s) or alignment device at other locations may be provided for
convenience. The means used for placement of a dosimeter(s) (i.e., hole
size) and the type of dosimeter(s) used is at the discretion of the
manufacturer. Any effect on the doses measured due to the removal of
phantom material to accommodate dosimeters shall be accounted for
through appropriate corrections to the reported data or included in the
statement of maximum deviation for the values obtained using the
phantom.
(7) Dose profile means the dose as a function of position along a
line.
(8) Modulation transfer function means the modulus of the Fourier
transform of the impulse response of the system.
(9) Multiple tomogram system means a CT x-ray system which obtains
x-ray transmission data simultaneously during a single scan to produce
more than one tomogram.
(10) Noise means the standard deviation of the fluctuations in CT
number expressed as a percent of the attenuation coefficient of water.
Its estimate (S<INF>n</INF>) is calculated using the following
expression:
[GRAPHIC] [TIFF OMITTED] TC01AP93.001
where:
CS=Contrast scale.
[mu]<INF>w</INF>=Linear attenuation coefficient of water.
s=Estimated standard deviation of the CT numbers of picture elements in
a specified area of the CT image.
(11) Nominal tomographic section thickness means the full-width at
half-maximum of the sensitivity profile taken at the center of the
cross-sectional volume over which x-ray transmission data are collected.
(12) Picture element means an elemental area of a tomogram.
(13) Remanufacturing means modifying a CT system in such a way that
the resulting dose and imaging performance become substantially
equivalent to any CT x-ray system manufactured by the original
manufacturer on or after November 29, 1984. Any reference in this
section to ``manufacture'', ``manufacturer'', or ``manufacturing''
includes remanufacture, remanufacturer, or remanufacturing,
respectively.
(14) Scan increment means the amount of relative displacement of the
patient with respect to the CT x-ray system between successive scans
measured along the direction of such displacement.
(15) Scan sequence means a preselected set of two or more scans
performed consecutively under preselected CT conditions of operations.
(16) Sensitivity profile means the relative response of the CT x-ray
system as a function of position along a line perpendicular to the
tomographic plane.
(17) Single tomogram system means a CT x-ray system which obtains x-
ray transmission data during a scan to produce a single tomogram.
(18) Tomographic plane means that geometric plane which the
manufacturer identifies as corresponding to the output tomogram.
(19) Tomographic section means the volume of an object whose x-ray
attenuation properties are imaged in a tomogram.
(c) Information to be provided for users. Each manufacturer of a CT
x-ray system shall provide the following technical and safety
information, in addition to that required under Sec. 1020.30(h), to
purchasers and, upon request, to others at a cost not to exceed the cost
of publication and distribution of such information. This information
shall be identified and provided in a separate section of the user's
instruction manual or in a separate manual devoted only to this
information.
(1) Conditions of operation. A statement of the CT conditions of
operation used to provide the information required by paragraph (c) (2)
and (3) of this section.
(2) Dose information. The following dose information obtained by
using the CT dosimetry phantom. For any CT x-ray system designed to
image both the head and body, separate dose information shall be
provided for each application. All dose measurements shall be performed
with the CT dosimetry phantom placed on the patient couch or support
device without additional attenuating materials present.
(i) The CTDI at the following locations in the dosimetry phantom:
(a) Along the axis of rotation of the phantom.
(b) Along a line parallel to the axis of rotation and 1.0 centimeter
interior to the surface of the phantom with the phantom positioned so
that CTDI is the maximum obtainable at this depth.
(c) Along lines parallel to the axis of rotation and 1.0 centimeter
interior to the surface of the phantom at positions 90, 180, and 270
degrees from the position in paragraph (c)(2)(i)(b) of this section. The
CT conditions of operation shall be the typical values suggested by the
manufacturer for CT of the head or body. The location of the position
where the CTDI is maximum as specified in paragraph (c)(2)(i)(b) of this
section shall be given by the manufacturer with respect to the housing
of the scanning mechanism or other readily identifiable feature of the
CT x-ray system in such a manner as to permit placement of the dosimetry
phantom in this orientation.
(ii) The CTDI in the center location of the dosimetry phantom for
each selectable CT condition of operation that varies either the rate or
duration of x-ray exposure. This CTDI shall be presented as a value that
is normalized to the CTDI in the center location of the dosimetry
phantom from paragraph (c)(2)(i) of this section, with the CTDI of
paragraph (c)(2)(i) of this section having a value of one. As each
individual CT condition of operation is changed, all other independent
CT conditions of operation shall be maintained at the typical values
described in paragraph (c)(2)(i) of this section. These data shall
encompass the range of each CT condition of operation stated by the
manufacturer as appropriate for CT of the head or body. When more than
three selections of a CT condition of operation are available, the
normalized CTDI shall be provided, at least, for the minimum, maximum,
and mid-range value of the CT condition of operation.
(iii) The CTDI at the location coincident with the maximum CTDI at 1
centimeter interior to the surface of the dosimetry phantom for each
selectable peak tube potential. When more than three selections of peak
tube potential are available, the normalized CTDI shall be provided, at
least, for the minimum, maximum, and a typical value of peak tube
potential. The CTDI shall be presented as a value that is normalized to
the maximum CTDI located at 1 centimeter interior to the surface of the
dosimetry phantom from paragraph (c)(2)(i) of this section, with the
CTDI of paragraph (c)(2)(i) of this section having a value of one.
(iv) The dose profile in the center location of the dosimetry
phantom for each selectable nominal tomographic section thickness. When
more than three selections of nominal tomographic section thicknesses
are available, the information shall be provided, at least, for the
minimum, maximum, and midrange value of nominal tomographic section
thickness. The dose profile shall be presented on the same
graph and to the same scale as the corresponding sensitivity profile
required by paragraph (c)(3)(iv) of this section.
(v) A statement of the maximum deviation from the values given in
the information provided according to paragraph (c)(2) (i), (ii), (iii),
and (iv) of this section. Deviation of actual values may not exceed
these limits.
(3) Imaging performance information. The following performance data
shall be provided for the CT conditions of operation used to provide the
information required by paragraph (c)(2)(i) of this section. All other
aspects of data collection, including the x-ray attenuation properties
of the material in the tomographic section, shall be similar to those
used to provide the dose information required by paragraph (c)(2)(i) of
this section. For any CT x-ray system designed to image both the head
and body, separate imaging performance information shall be provided for
each application.
(i) A statement of the noise.
(ii) A graphical presentation of the modulation transfer function
for the same image processing and display mode as that used in the
statement of the noise.
(iii) A statement of the nominal tomographic section thickness(es).
(iv) A graphical presentation of the sensitivity profile, at the
location corresponding to the center location of the dosimetry phantom,
for each selectable nominal tomographic section thickness for which the
dose profile is given according to paragraph (c)(2)(iv) of this section.
(v) A description of the phantom or device and test protocol or
procedure used to determine the specifications and a statement of the
maximum deviation from the specifications provided in accordance with
paragraphs (c)(3) (i), (ii), (iii), and (iv) of this section. Deviation
of actual values may not exceed these limits.
(d) Quality assurance. The manufacturer of any CT x-ray system shall
provide the following with each system. All information required by this
subsection shall be provided in a separate section of the user's
instructional manual.
(1) A phantom(s) capable of providing an indication of contrast
scale, noise, nominal tomographic section thickness, the spatial
resolution capability of the system for low and high contrast objects,
and measuring the mean CT number of water or a reference material.
(2) Instructions on the use of the phantom(s) including a schedule
of testing appropriate for the system, allowable variations for the
indicated parameters, and a method to store as records, quality
assurance data.
(3) Representative images obtained with the phantom(s) using the
same processing mode and CT conditions of operation as in paragraph
(c)(3) of this section for a properly functioning system of the same
model. The representative images shall be of two forms as follows:
(i) Photographic copies of the images obtained from the image
display device.
(ii) Images stored in digital form on a storage medium compatible
with the CT x-ray system. The CT x-ray system shall be provided with the
means to display these images on the image display device.
(e) [Reserved]
(f) Control and indication of conditions of operation--(1) Visual
indication. The CT conditions of operation to be used during a scan or a
scan sequence shall be indicated prior to initiation of a scan or a scan
sequence. On equipment having all or some of these conditions of
operation at fixed values, this requirement may be met by permanent
markings. Indication of the CT conditions of operation shall be visible
from any position from which scan initiation is possible.
(2) Timers. (i) Means shall be provided to terminate the x-ray
exposure automatically by either deenergizing the x-ray source or
shuttering the x-ray beam in the event of equipment failure affecting
data collection. Such termination shall occur within an interval that
limits the total scan time to no more than 110 percent of its preset
value through the use of either a backup timer or devices which monitor
equipment function. A visible signal shall indicate when the x-ray
exposure has been terminated through these means and manual resetting of
the CT
conditions of operation shall be required prior to the initiation of
another scan.
(ii) Means shall be provided so that the operator can terminate the
x-ray exposure at any time during a scan, or series of scans under x-ray
system control, of greater than one-half second duration. Termination of
the x-ray exposure shall necessitate resetting of the CT conditions of
operation prior to the initiation of another scan.
(g) Tomographic plane indication and alignment. (1) For any single
tomogram system, means shall be provided to permit visual determination
of the tomographic plane or a reference plane offset from the
tomographic plane.
(2) For any multiple tomogram system, means shall be provided to
permit visual determination of the location of a reference plane. The
relationship of the reference plane to the planes of the tomograms shall
be provided to the user in addition to other information provided
according to Sec. 1020.30(h). This reference plane can be offset from
the location of the tomographic planes.
(3) The distance between the indicated location of the tomographic
plane or reference plane and its actual location may not exceed 5
millimeters.
(4) For any offset alignment system, the manufacturer shall provide
specific instructions with respect to the use of this system for patient
positioning, in addition to other information provided according to
Sec. 1020.30(h).
(5) If a mechanism using a light source is used to satisfy the
requirements of paragraphs (g) (1) and (2) of this section, the light
source shall allow visual determination of the location of the
tomographic plane or reference plane under ambient light conditions of
up to 500 lux.
(h) Beam-on and shutter status indicators. (1) Means shall be
provided on the control and on or near the housing of the scanning
mechanism to provide visual indication when and only when x rays are
produced and, if applicable, whether the shutter is open or closed. If
the x-ray production period is less than one-half second, the indication
of x-ray production shall be actuated for one-half second. Indicators at
or near the housing of the scanning mechanism shall be discernible from
any point external to the patient opening where insertion of any part of
the human body into the primary beam is possible.
(2) For systems that allow high voltage to be applied to the x-ray
tube continuously and that control the emission of x rays with a
shutter, the radiation emitted may not exceed 100 milliroentgens
(2.58x10<SUP>-5</SUP> coulomb/kilogram) in 1 hour at any point 5
centimeters outside the external surface of the housing of the scanning
mechanism when the shutter is closed. Compliance shall be determined by
measurements averaged over an area of 100 square centimeters with no
linear dimensions greater than 20 centimeters.
(i) Scan increment accuracy. The deviation of indicated scan
increment from actual scan increment may not exceed 1 millimeter.
Compliance shall be measured as follows: The determination of the
deviation of indicated versus actual scan increment shall be based on
measurements taken with a mass 100 kilograms or less, on the patient
support device. The patient support device shall be incremented from a
typical starting position to the maximum incrementation distance or 30
centimeters, whichever is less, and then returned to the starting
position. Measurement of actual versus indicated scan increment may be
taken anywhere along this travel.
(j) CT number mean and standard deviation. (1) A method shall be
provided to calculate the mean and standard deviation of CT numbers for
an array of picture elements about any location in the image. The number
of elements in this array shall be under user control.
(2) The manufacturer shall provide specific instructions concerning
the use of the method provided for calculation of CT number mean and
standard deviation in addition to other information provided according
to Sec. 1020.30(h).
[49 FR 34712, Aug. 31, 1984; 49 37381, Sept. 24, 1984, as amended at 49
FR 47388, Dec. 4, 1984; 56 FR 36098, Aug. 1, 1991; 67 FR 9587, Mar. 4,
2002]
Effective Date Note: At 70 FR 34042, June 10, 2005, Sec. 1020.33
was amended by revising paragraph (h)(2), effective June 10, 2006. For
the convenience of the user, the revised text is set forth as follows:
Sec. 1020.33 Computed tomography (CT) equipment.
* * * * *
(h) * * *
(2) For systems that allow high voltage to be applied to the x-ray
tube continuously and that control the emission of x-ray with a shutter,
the radiation emitted may not exceed 0.88 milligray (vice 100
milliroentgen exposure) in 1 hour at any point 5 cm outside the external
surface of the housing of the scanning mechanism when the shutter is
closed. Compliance shall be determined by measurements average over an
area of 100 square cm with no linear dimension greater than 20 cm.
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* * * * *
Sec. 1020.40 Cabinet x-ray systems.
(a) Applicability. The provisions of this section are applicable to
cabinet x-ray systems manufactured or assembled on or after April 10,
1975, except that the provisions as applied to x-ray systems designed
primarily for the inspection of carry-on baggage are applicable to such
systems manufactured or assembled on or after April 25, 1974. The
provisions of this section are not applicable to systems which are
designed exclusively for microscopic examination of material, e.g., x-
ray diffraction, spectroscopic, and electron microscope equipment or to
systems for intentional exposure of humans to x-rays.
(b) Definitions. As used in this section the following definitions
apply:
(1) Access panel means any barrier or panel which is designed to be
removed or opened for maintenance or service purposes, requires tools to
open, and permits access to the interior of the cabinet.
(2) Aperture means any opening in the outside surface of the
cabinet, other than a port, which remains open during generation of x
radiation.
(3) Cabinet x-ray system means an x-ray system with the x-ray tube
installed in an enclosure (hereinafter termed cabinet) which,
independently of existing architectural structures except the floor on
which it may be placed, is intended to contain at least that portion of
a material being irradiated, provide radiation attenuation, and exclude
personnel from its interior during generation of x radiation. Included
are all x-ray systems designed primarily for the inspection of carry-on
baggage at airline, railroad, and bus terminals, and in similar
facilities. An x-ray tube used within a shielded part of a building, or
x-ray equipment which may temporarily or occasionally incorporate
portable shielding is not considered a cabinet x-ray system.
(4) Door means any barrier which is designed to be movable or opened
for routine operation purposes, does not generally require tools to
open, and permits access to the interior of the cabinet. For the
purposes of paragraph (c)(4)(i) of this section, inflexible hardware
rigidly affixed to the door shall be considered part of the door.
(5) Exposure means the quotient of dQ by dm where dQ is the absolute
value of the total charge of the ions of one sign produced in air when
all the electrons (negatrons and positrons) liberated by photons in a
volume element of air having mass dm are completely stopped in air.
(6) External surface means the outside surface of the cabinet x-ray
system, including the high-voltage generator, doors, access panels,
latches, control knobs, and other permanently mounted hardware and
including the plane across any aperture or port.
(7) Floor means the underside external surface of the cabinet.
(8) Ground fault means an accidental electrical grounding of an
electrical conductor.
(9) Port means any opening in the outside surface of the cabinet
which is designed to remain open, during generation of x-rays, for the
purpose of conveying material to be irradiated into and out of the
cabinet, or for partial insertion for irradiation of an object whose
dimensions do not permit complete insertion into the cabinet.
(10) Primary beam means the x radiation emitted directly from the
from the target and passing through the window of the x-ray tube.
(11) Safety interlock means a device which is intended to prevent
the generation of x radiation when access by any part of the human body
to the interior of the cabinet x-ray system through a door or access
panel is possible.
(12) X-ray system means an assemblage of components for the
controlled generation of x-rays.
(13) X-ray tube means any electron tube which is designed for the
conversion of electrical energy into x-ray energy.
(c) Requirements--(1) Emission limit. (i) Radiation emitted from the
cabinet x-ray system shall not exceed an exposure of 0.5 milliroentgen
in one hour at any point five centimeters outside the external surface.
(ii) Compliance with the exposure limit in paragraph (c)(1)(i) of
this section shall be determined by measurements averaged over a cross-
sectional area of ten square centimeters with no linear dimension
greater than 5 centimeters, with the cabinet x-ray system operated at
those combinations of x-ray tube potential, current, beam orientation,
and conditions of scatter radiation which produce the maximum x-ray
exposure at the external surface, and with the door(s) and access
panel(s) fully closed as well as fixed at any other position(s) which
will allow the generation of x radiation.
(2) Floors. A cabinet x-ray system shall have a permanent floor. Any
support surface to which a cabinet x-ray system is permanently affixed
may be deemed the floor of the system.
(3) Ports and apertures. (i) The insertion of any part of the human
body through any port into the primary beam shall not be possible.
(ii) The insertion of any part of the human body through any
aperture shall not be possible.
(4) Safety interlocks. (i) Each door of a cabinet x-ray system shall
have a minimum of two safety interlocks. One, but not both of the
required interlocks shall be such that door opening results in physical
disconnection of the energy supply circuit to the high-voltage
generator, and such disconnection shall not be dependent upon any moving
part other than the door.
(ii) Each access panel shall have at least one safety interlock.
(iii) Following interruption of x-ray generation by the functioning
of any safety interlock, use of a control provided in accordance with
paragraph (c)(6)(ii) of this section shall be necessary for resumption
of x-ray generation.
(iv) Failure of any single component of the cabinet x-ray system
shall not cause failure of more than one required safety interlock.
(5) Ground fault. A ground fault shall not result in the generation
of x-rays.
(6) Controls and indicators for all cabinet x-ray systems. For all
systems to which this section is applicable there shall be provided:
(i) A key-actuated control to insure that x-ray generation is not
possible with the key removed.
(ii) A control or controls to initiate and terminate the generation
of x-rays other than by functioning of a safety interlock or the main
power control.
(iii) Two independent means which indicate when and only when x-rays
are being generated, unless the x-ray generation period is less than
one-half second, in which case the indicators shall be activated for
one-half second, and which are discernible from any point at which
initiation of x-ray generation is possible. Failure of a single
component of the cabinet x-ray system shall not cause failure of both
indicators to perform their intended function. One, but not both, of the
indicators required by this subdivision may be a milliammeter labeled to
indicate x-ray tube current. All other indicators shall be legibly
labeled ``X-RAY ON''.
(iv) Additional means other than milliammeters which indicate when
and only when x-rays are being generated, unless the x-ray generation
period is less than one-half second in which case the indicators shall
be activated for one-half second, as needed to insure that at least one
indicator is visible from each door, access panel, and port, and is
legibly labeled ``X-RAY ON''.
(7) Additional controls and indicators for cabinet x-ray systems
designed to admit humans. For cabinet x-ray systems designed to admit
humans there shall also be provided:
(i) A control within the cabinet for preventing and terminating x-
ray generation, which cannot be reset, overridden or bypassed from the
outside of the cabinet.
(ii) No means by which x-ray generation can be initiated from within
the cabinet.
(iii) Audible and visible warning signals within the cabinet which
are actuated for at least 10 seconds immediately prior to the first
initiation of x-ray generation after closing any door designed to admit
humans. Failure of any single component of the cabinet x-ray system
shall not cause failure of both the audible and visible warning signals.
(iv) A visible warning signal within the cabinet which remains
actuated when and only when x-rays are being generated, unless the x-ray
generation period is less than one-half second in which case the
indicators shall be activated for one-half second.
(v) Signs indicating the meaning of the warning signals provided
pursuant to paragraphs (c)(7) (iii) and (iv) of this section and
containing instructions for the use of the control provided pursuant to
paragraph (c)(7)(i) of this section. These signs shall be legible,
accessible to view, and illuminated when the main power control is in
the ``on'' position.
(8) Warning labels. (i) There shall be permanently affixed or
inscribed on the cabinet x-ray system at the location of any controls
which can be used to initiate x-ray generation, a clearly legible and
visible label bearing the statement:
Caution: X-Rays Produced When Energized
(ii) There shall be permanently affixed or inscribed on the cabinet
x-ray system adjacent to each port a clearly legible and visible label
bearing the statement:
caution: Do Not Insert Any Part of the Body When System is Energized--X-
ray Hazard
(9) Instructions. (i) Manufacturers of cabinet x-ray systems shall
provide for purchasers, and to others upon request at a cost not to
exceed the cost of preparation and distribution, manuals and
instructions which shall include at least the following technical and
safety information: Potential, current, and duty cycle ratings of the x-
ray generation equipment; adequate instructions concerning any
radiological safety procedures and precautions which may be necessary
because of unique features of the system; and a schedule of maintenance
necessary to keep the system in compliance with this section.
(ii) Manufacturers of cabinet x-ray systems which are intended to be
assembled or installed by the purchaser shall provide instructions for
assembly, installation, adjustment and testing of the cabinet x-ray
system adequate to assure that the system is in compliance with
applicable provisions of this section when assembled, installed,
adjusted and tested as directed.
(10) Additional requirements for x-ray baggage inspection systems.
X-ray systems designed primarily for the inspection of carry-on baggage
at airline, railroad, and bus terminals, and at similar facilities,
shall be provided with means, pursuant to paragraphs (c)(10) (i) and
(ii) of this section, to insure operator presence at the control area in
a position which permits surveillance of the ports and doors during
generation of x-radiation.
(i) During an exposure or preset succession of exposures of one-half
second or greater duration, the means provided shall enable the operator
to terminate the exposure or preset succession of exposures at any time.
(ii) During an exposure or preset succession of exposures of less
than one-half second duration, the means provided may allow completion
of the exposure in progress but shall enable the operator to prevent
additional exposures.
(d) Modification of a certified system. The modification of a
cabinet x-ray system, previously certified pursuant to Sec. 1010.2 by
any person engaged in the business of manufacturing, assembling or
modifying cabinet x-ray systems shall be construed as manufacturing
under the act if the modification affects any aspect of the system's
performance for which this section has an applicable requirement. The
manufacturer who performs such modification shall recertify and
reidentify the system in accordance with the provisions of Sec. Sec.
1010.2 and 1010.3 of this chapter.
[39 FR 12986, Apr. 10, 1974]
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