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 all stationary, transportable, mobile,
portable, and hand-held X-ray systems for veterinary use.
4.12.1 Administrative Requirements. All
provisions of
RHB 4.2 apply, except 4.2.2,
4.2.7, and 4.2.11. No person other than a licensed veterinarian or an
adequately trained individual, as required by
RHB 4.12.22, shall use
equipment emitting ionizing radiation for diagnostic purposes.
4.12.2 Radiation Protection. All provisions
of RHB 4.2.9
apply, except 4.2.9.3.
4.12.3
Holding of Patients and Films. All provisions of
RHB 4.2.12 apply. In
addition:
4.12.3.1 Each human holder in a
veterinary facility shall utilize protective apparel.
4.12.3.2 Each veterinary facility that holds
patients shall provide personnel monitoring devices. If the human holder's
hands are in or near the primary beam and lead gloves are not utilized, then
ring badges shall also be provided and worn.
4.12.4 General Requirements. All provisions
of RHB 4.3 and
4.4 apply.
4.12.5 Means shall be
provided for independent stepless adjustment of at least two (2) dimensions of
the x-ray field.
4.12.6 Means shall
be provided to indicate when the axis of the x-ray beam is perpendicular to the
plane of the image receptor.
4.12.7
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 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.
4.12.8 The beam-limiting device shall
indicate numerically the field size in the plane of the image receptor to which
it is adjusted.
4.12.9 Indication
of field size dimensions and SID's 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.
4.12.10 The
beam-limiting device shall be provided with SID scales that reflect the actual
SID(s) used for radiographic procedures.
4.12.10.1 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.
4.12.10.2 Diaphragms or cones when provided
for collimating the useful beam to the area of clinical interest shall meet the
requirements of
RHB 4.7.2.
4.12.10.3 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).
4.12.11 Radiation Exposure Control
Devices.
4.12.11.1 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 has been set to a "zero (0)" or "off" position if either
position is provided.
4.12.11.2
X-ray Control.
4.12.11.2.1 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 (0.5) second or less, or during serial radiography when means shall
be provided to permit completion of any single exposure of the series in
process.
4.12.11.2.2 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.
4.12.11.2.3 Timer Reproducibility. With a
timer setting of one-half (0.5) second 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 test are
performed: T >= 5 (Tmax - Tmin).
4.12.12 Exposure Reproducibility. The
coefficient of variation of exposure shall not exceed 0.05 when all technique
factors are held constant. This requirement shall be deemed to have been met
if, when four 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).
4.12.13 Radiation
from Capacitor Energy Storage Equipment in Standby Status. Radiation emitted
from the x-ray tube when the exposure switch or timer is not activated shall
not exceed a rate of two milliRoentgen (2 mR) per hour at five centimeters (5
cm) from any accessible surface of the diagnostic source assembly, with the
beam-limiting device fully open.
4.12.14 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.
4.12.15 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.
4.12.15.1 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.
4.12.15.2 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.
4.12.15.3 Measuring compliance. Determination
of compliance shall be based on four (4) exposures, at each of the two (2)
settings. These 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.
4.12.16 Light Localization.
4.12.16.1 When a light field 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.
4.12.16.2 Exemptions to
RHB 4.12.16.1 shall be
granted if the registrant demonstrates to the Department that their equipment
is unable to meet this regulation.
4.12.17 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%).
4.12.18 Fluoroscopic X-ray Systems.
Veterinary fluoroscopic x-ray systems shall meet the following requirements:
4.12.18.1 Limitation of Useful Beam.
4.12.18.1.1 Primary Barrier.
4.12.18.1.1.1 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.
4.12.18.1.1.2 The x-ray tube used for
fluoroscopy shall not produce x-rays unless the barrier is in position to
intercept the entire useful beam.
4.12.18.1.2 X-ray Field. The x-ray field
produced by non-image intensified fluoroscopic equipment shall not extend
beyond the entire visible area of the image receptor. This requirement applies
to field size for both fluoroscopic procedures and spot filming procedures. In
addition:
4.12.18.1.2.1 Means shall be
provided for stepless adjustment of the field size;
4.12.18.1.2.2 The minimum field size at the
greatest SID shall be equal to or less than five centimeters by five
centimeters (5 cm x 5 cm).
4.12.18.1.2.3 For image-intensified
fluoroscopic equipment, 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 three percent (3%) of the SID. The sum of the
excess length and the excess width shall be no greater than four percent (4%)
of the SID. In addition, means shall be provided to permit further limitation
of the field.
4.12.18.2 Activation of the Fluoroscopic
Tube. X-ray production in the fluoroscopic mode shall be controlled by a device
which requires continuous pressure by the fluoroscopist for the entire time of
any exposure. When recording serial fluoroscopic images, the fluoroscopist
shall be able to terminate the x-ray exposure(s) at any time, but means shall
be provided to permit completion of any single exposure of the series in
process.
4.12.18.3 Barrier
Transmitted Radiation Rate Limits.
4.12.18.3.1
The exposure rate due to transmission through the primary protective barrier
with the attenuation block in the useful beam, combined with radiation from the
image intensifier, if provided, shall not exceed two milliRoentgen (2 mR)(0.516
uC/kg) per hour at ten centimeters (10 cm) from any accessible surface of the
fluoroscopic imaging assembly beyond the plane of the image receptor for each
Roentgen per minute of entrance exposure rate.
4.12.18.3.2 Measuring Compliance of Barrier
Transmission.
4.12.18.3.2.1 The exposure rate
due to transmission through the protective barrier with the attenuation block
in the useful beam, combined with radiation from the image intensifier shall be
determined by measurements averaged over an area of one hundred square
centimeters (100 cm2) with no linear dimension
greater than twenty centimeters (20 cm).
4.12.18.3.2.2 If the source is below the
tabletop, the measurement shall be made with the input surface of the
fluoroscopic imaging assembly positioned thirty centimeters (30 cm) above the
tabletop.
4.12.18.3.2.3 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 thirty
centimeters (30 cm).
4.12.18.4 Indication of Potential and
Current. During fluoroscopy the kV and mA shall be continuously
indicated.
4.12.18.5 Mobile
Fluoroscopes. In addition to the other requirements of this Part, mobile
fluoroscopes shall provide intensified imaging.
4.12.18.6 Control of Scattered Radiation.
4.12.18.6.1 Fluoroscopic table designs when
combined with procedures utilized shall be such that no unprotected part of any
staff or ancillary individual's body shall be exposed to unattenuated scattered
radiation which originates from under the table. The attenuation required shall
be not less than 0.25 millimeter lead equivalent.
4.12.18.6.2 Equipment configuration when
combined with procedures shall be such that no portion of any staff or
ancillary individual's body, except the extremities, shall be exposed to
unattenuated scattered radiation emanating from above the tabletop unless that
individual:
4.12.18.6.2.1 Is at least one
hundred twenty centimeters (120 cm) from the center of the useful beam,
or
4.12.18.6.2.2 The radiation has
passed through not less than 0.25 millimeter lead equivalent material
including, but not limited to, drapes, bucky-slot cover panel, or
self-supporting curtains, in addition to any lead equivalency provided by the
protective apparel referred to in
RHB 4.12.3.1.
4.12.19
X-ray Systems Designed for One Image Receptor Size. Radiographic equipment
designed for only one (1) image receptor size 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.
4.12.20 Veterinary Computed Tomography X-ray
Systems - Where applicable, all provisions of
RHB 4.11 apply.
4.12.21 Veterinary Dental Systems - Where
applicable, all provisions of
RHB 4.5 and 4.6
apply.
4.12.22 Training Plan
Requirements. The registrant shall maintain a written training plan, available
for Departmental review, to include all parts of RHB 4.12.22.1.
4.12.22.1 The registrant shall require
persons operating registered equipment and associate equipment and/or holding
patients to receive, at a minimum, instruction in the following areas:
4.12.22.1.1 Radiation Protection. Training in
radiation protection standards shall include, but are not limited to,
protective clothing; patient holding; time, distance, and shielding; dose
limits specified in Part III of this regulation; use of personnel monitoring
devices; and the biological effects of radiation.
4.12.22.1.2 Darkroom Techniques/Digital
Imaging Acquisition Systems. Training in darkroom techniques shall include, but
is not limited to, developing chemicals; film protection; cassettes; and
screens. Training in digital imaging acquisition systems shall follow protocol
established by the manufacturer of the digital imaging acquisition
system.
4.12.22.1.3 Machine
Specific Training. Training shall include, at a minimum, machine functions;
machine safety procedures; recognizing machine problems; patient positioning
for x-ray exams; and radiographic techniques.
4.12.22.2 Instruction required by
RHB 4.12.22.1 shall be
completed prior to the operator working independently. Such training shall be
certified in writing by the Radiation Safety Officer and records shall be made
available for Departmental review.
