Current through Register Vol. 48, No. 9, September 27, 2024
In addition to the applicable provisions of this regulation,
the requirements of this Part apply to x-ray equipment and associated
facilities used for radiography with stationary and transportable radiographic
systems other than intraoral dental, fluoroscopic, computed tomography (CT),
mammography, or veterinary medical systems.
4.7.1 Stationary and Transportable General
Purpose Units. In addition to the other provisions of this Part, all stationary
and transportable general purpose units must also meet the following
requirements:
4.7.1.1 Means shall be provided
for independent stepless adjustment of at least two (2) dimensions of the x-ray
field.
4.7.1.2 Means shall be
provided to indicate when the axis of the x-ray beam is perpendicular to the
plane of the image receptor.
4.7.1.3 Means shall be provided for visually
defining the perimeter of the x-ray field. 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
two percent (2%) 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.
4.7.1.4 The
beam limiting device shall indicate numerically the field size in the plane of
the image receptor to which it is adjusted.
4.7.1.5 Indication of field size dimensions
and SIDs used shall be specified in inches and/or centimeters on the
collimator. The indications on the collimator shall be such that aperture
adjustments result in x-ray field dimensions in the plane of the image receptor
which correspond to those of the image receptor to within two percent (2%) of
the SID when the beam axis is perpendicular to the plane of the image
receptor.
4.7.1.6 The beam limiting
device shall be provided with SID scales that reflect the actual SID(s) used
for radiographic procedures.
4.7.1.7 Means shall be provided to align the
center of the x-ray field with the center of the image receptor to within two
percent (2%) of the SID.
4.7.2 X-ray Systems Designed with a fixed
collimator. Radiographic equipment designed with a fixed collimator at a fixed
SID shall be provided with means to limit the field at the plane of the image
receptor, and to align the center of the x-ray field with the center of the
image receptor to within two percent (2%) 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.
4.7.3 Special Purpose
X-ray Systems. In addition to the other provisions of this Part, all special
purpose x-ray systems shall also meet the following requirements:
4.7.3.1 Means shall be provided to limit the
x-ray field in the plane of the image receptor such that the x-ray field does
not exceed each dimension of the image receptor by more than two percent (2%)
of the SID when the axis of the x-ray beam is perpendicular to the plane of the
image receptor.
4.7.3.2 Means shall
be provided to align the center of the x-ray field with the center of the image
receptor to within two percent (2%) 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.
Compliance shall be determined with the axis of the x-ray beam perpendicular to
the plane of the image receptor.
4.7.3.3 The above
RHB 4.7.3.1 and 4.7.3.2 may
be met with a system that meets the requirements for a general purpose x-ray
system as specified in
RHB 4.7.3 or, when alignment
means are also provided, may be met with either:
4.7.3.3.1 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
4.7.3.3.2 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.
4.7.4 Radiation Exposure Control Devices.
4.7.4.1 Timers. Means shall be provided to
terminate the exposure at a preset time interval, preset product of current and
time, a preset number of pulses, or a preset radiation exposure to the image
receptor. In addition, it shall not be possible to make an exposure when the
timer is set to a "zero (0)" or "off" position if either position is
provided.
4.7.4.2 X-ray Control.
4.7.4.2.1 An x-ray control shall be
incorporated into each x-ray system such that an exposure can be terminated by
the operator at any time (dead man's switch) except for exposures of one-half
(1/2) second or less, or during serial radiography when means shall be provided
to permit completion of any single exposure of the series in process.
4.7.4.2.2 Stationary and transportable x-ray
systems shall have the x-ray control permanently mounted in a protected area so
that the operator is required to remain in that protected area during the
entire exposure to include the requirements of Appendix C.
4.7.4.2.3 The x-ray control shall provide
visual indication observable at or from the operator protected position
whenever x-rays are produced. In addition, a signal audible to the operator
shall indicate that the exposure has terminated.
4.7.4.2.4 The x-ray control shall be so
placed that the operator can view the patient during any exposure and still
stand in a protected area.
4.7.4.2.5 Automatic Exposure Controls. When
an automatic exposure control is provided:
4.7.4.2.5.1 Indication shall be made on the
control panel when this mode of operation is selected;
4.7.4.2.5.2 If the x-ray tube potential is
equal to or greater than fifty kilovoltage peak (50 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 (2) pulses;
4.7.4.2.5.3 The minimum exposure time for all
equipment other than that specified in
RHB 4.7.4.2.5.2 shall
be equal to or less than one-sixtieth (1/60) second or a time interval required
to deliver five milliAmpere-seconds (5 mAs), whichever is greater;
4.7.4.2.5.4 Either the product of peak x-ray
tube potential, current, and exposure time shall be limited to not more than
sixty kilowatt-seconds (60 kWs) per exposure, or the product of x-ray tube
current and exposure time shall be limited to not more than six hundred
milliAmpere-seconds (600 mAs) per exposure except that, when the x-ray tube
potential is less than fifty kilovoltage peak (50 kVp), the product of x-ray
tube current and exposure time shall be limited to not more than two thousand
milli Ampere-seconds (2000 mAs) per exposure; and
4.7.4.2.5.5 A visible signal shall indicate
when an exposure has been terminated at the limits required by
RHB 4.7.4.2.5.4, and
manual resetting shall be required before further automatically timed exposures
can be made.
4.7.4.2.6
Timer Reproducibility. With a timer setting of one-half second (0.5 s) or less,
the average exposure period (T) shall be greater than or equal to five (5)
times the maximum exposure period (Tmax) minus the minimum exposure period
(Tmin) when four (4) timer tests are performed: T >= 5 (Tmax -
Tmin).
4.7.5
Exposure Reproducibility. The coefficient of variation of exposure shall not
exceed 0.05 when all selectable technique factors are held constant. This
requirement shall be deemed to have been met if, when four (4) exposures are
made at identical technique factors, the value of the average exposure (E) is
greater than or equal to five (5) times the maximum exposure (Emax) minus the
minimum exposure (Emin): E >= 5 (Emax - Emin).
4.7.6 Accuracy. Deviation of technique
factors from indicated values shall not exceed the limits specified for that
system by its manufacturer. In the absence of manufacturer's specifications,
the deviation shall not exceed ten percent (10%) of the indicated
value.
4.7.7 Linearity. The
following requirements apply when the equipment is operated on a power supply
as specified by the manufacturer for any fixed x-ray tube potential within the
range of forty percent to one hundred percent (40% to 100%) of the maximum
rated.
4.7.7.1 Equipment having independent
selection of x-ray tube current (mA). The average ratios of exposure to the
indicated milli Ampere-seconds product (C/kg/mAs (or mR/mAs)) obtained at any
tube current settings shall not differ by more than 0.10 times their sum. This
is: [X1-X2] < 0.10 (X1+X2); where X1 and X2 are the average C/kg/mAs (or
mR/mAs) values obtained at any two (2) tube current settings.
4.7.7.2 Equipment having a combined x-ray
tube current-exposure time product (mAs) selector, but not a separate tube
current (mA) selector. The average ratios of exposure to the indicated
milliAmpere-seconds product (C/kg/mAs (or mR/mAs)) obtained at any two (2) mAs
selector settings shall not differ by more than 0.10 times their sum. This is :
[X1-X2] < 0.10 (X1+X2); where X1 and X2 are the average C/kg/mAs (or mR/mAs)
values obtained at any two mAs selector settings.
4.7.7.3 Measuring Compliance. Determination
of compliance shall be based on four (4) exposures, at each of the two (2)
settings. The two (2) settings may include any two (2) focal spot sizes
provided that neither focal spot size is equal to or less than 0.45 millimeter,
in which case the two (2) settings shall be restricted to the same focal spot
size. For purposes of this requirement, focal spot size is the nominal focal
spot size specified by the x-ray tube manufacturer.
4.7.8 Light Localization.
4.7.8.1 When a light localizer is used to
define the x-ray field, it shall provide an average illumination of not less
than fifteen footcandles (15 fc) at one hundred centimeters (100 cm) or at the
maximum SID, whichever is less. The average illumination shall be based upon
measurements made in the approximate center of each quadrant of the light
field.
4.7.8.2 Exemptions to
RHB 4.7.8.1 shall be
granted if the registrant demonstrates to the Department that their equipment
is unable to meet this regulation, and the Department determines that patient
safety or image quality is not compromised.
4.7.9 Certified Systems. In addition to the
requirements of these rules, the registrant shall not make, nor cause to be
made, any modification of components or installations of components certified
pursuant to U.S. Food and Drug Administration Regulation
21 CFR
1020"Performance Standards for Ionizing
Radiation Emitting Products" in any manner that could cause the installations
or the components to fail to meet the requirements of the applicable Parts of
the standards specified in 21 CFR 1020, except where a
variance has been granted by the Director, Center for Devices and Radiological
Health, Food and Drug Administration.
4.7.10 Maintenance Schedule. On all equipment
containing components certified pursuant to U.S. Food and Drug Administration
Regulation 21 CFR
1020"Performance Standards for Ionizing
Radiation Emitting Products," the registrant shall perform, or cause to be
performed, the schedule of maintenance provided by the manufacturer pursuant to
21 CFR
1020.30(h)(l)(ii). A log
book of such maintenance shall be maintained for inspection by the
Department.
4.7.11 SID Indication.
Means shall be provided to indicate the SID. SIDs shall be indicated in inches
and/or centimeters, and shall be indicated to within two percent
(2%).
4.7.12 Positive Beam
Limitation. For units having an operable positive beam limitation (PBL) system,
the following requirements must be met:
4.7.12.1 Neither the length nor width of the
x-ray field shall differ from the corresponding image receptor dimensions by
more than three percent (3%) of the SID; and
4.7.12.2 The sum of the length and width
differences, without regard to sign, shall not exceed four percent (4%) of the
SID.
4.7.12.3 The positive beam
limitation system shall be capable of operation, at the discretion of the
operator, such that the size of the field may be made smaller than the size of
the image receptor through stepless adjustment of the field size. The minimum
field size at an SID of one hundred centimeters (100 cm) shall be equal to or
less than five centimeters by five centimeters (5 cm x 5 cm).
4.7.12.4 The positive beam limitation system
shall be designed such that if a change in image receptor does not cause
automatic return to positive beam limitation function and any change of image
receptor size or SID must cause the automatic return.
4.7.12.5 PBL compliance shall be determined
with the beam axis perpendicular to the plane of the image receptor. Compliance
shall be determined no sooner than five (5) seconds after insertion of the
image receptor.
4.7.13
The useful beam shall be limited to the area of clinical interest. This shall
be deemed to have been met if a positive beam limiting device has been properly
used or if evidence of collimation has been shown on at least three (3) sides
or three (3) corners of the film (for example, projections from the shutters of
the collimator, cone cutting at the corners, or borders at the film's
edge).
4.7.14 Minimum Field Size.
The minimum field size at an SID of one hundred centimeters (100 cm) shall be
equal to or less than five centimeters by five centimeters (5 cm x 5
cm).
