[Code of Federal Regulations]
[Title 21, Volume 8]
[Revised as of April 1, 2002]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR1020.30]
[Page 593-603]
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. 1020.30 Diagnostic x-ray systems and their major components.
(a) Applicability--(1) The provisions of this section are applicable
to:
[[Page 594]]
(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 Secs. 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 Secs. 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
[[Page 595]]
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.
Xi = 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
[[Page 596]]
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:
Vn = No-load line potential and
Vi = 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.
[[Page 597]]
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 Secs. 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.
[[Page 598]]
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 Secs. 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 Secs. 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
[[Page 599]]
components with the applicable provisions of Secs. 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
Secs. 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 Secs. 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 Secs. 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 Secs. 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
[[Page 600]]
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 Secs. 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 Secs. 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 Secs. 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;
[[Page 601]]
(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
2.58x10-5 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-
[[Page 602]]
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 5.16x10-7 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..................................................
[[Page 603]]
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]