| (I) The air kerma rate due to transmission through
the primary protective barrier combined with radiation through the
image intensifier shall be determined by measurements averaged over
an area of 100 cm2 with no linear dimension
greater than 20 cm.
(II) 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.
(III) 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.
(IV) Movable grids and compression devices shall be
removed from the useful beam during the measurement.
(V) The attenuation block shall be positioned in the
useful beam 10 cm from the point of measurement of entrance air kerma
rate and between this point and the input surface of the fluoroscopic
imaging assembly.
(VI) The collimator shall be fully open when the measurement
is made.
(iii) X-ray field.
(I) Compliance with subclauses (II) - (VII) of this
clause shall be determined with the beam axis perpendicular to the
plane of the image receptor.
(II) Fluoroscopic radiation machine with a fixed SID
and the capability of a visible area of no greater than 300 cm2 shall be provided with either stepless adjustment
of the x-ray field or a means to further limit the x-ray field at
the image receptor to 125 cm2 less. If
the fluoroscopic radiation machine is provided with stepless adjustment,
the minimum x-ray field size at the maximum SID shall be less than
or equal to 5 cm by 5 cm at the image receptor.
(III) Fluoroscopic radiation machines with a variable
SID or a fixed SID with the capability of a visible area of greater
than 300 cm2 shall be provided with stepless
adjustment of the field size. The minimum x-ray field size at the
maximum SID shall be less than or equal to 5 cm by 5 cm at the image
receptor.
(IV) 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 3.0 percent of the
SID. The sum of the excess length and the excess width shall be no
greater than 4.0 percent of the SID.
(V) 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 that pass through
the center of the visible area of the image receptor.
(VI) For fluoroscopic radiation machines with only
a manual mode of collimation, the x-ray field produced shall be limited
to the area of the spot-film cassette at 16 inches above tabletop.
Additionally, during fluoroscopy, the beam shall be restricted to
the area of the input phosphor.
(VII) Spot-film devices shall meet the following additional
requirements.
(-a-) Means shall be provided between the source and
the animal for adjustment of the x-ray field size in the plane of
the film to the size of that portion of the film that has been selected
on the spot-film selector.
(-1-) Such adjustment shall be automatically accomplished
except when the x-ray field size in the plane of the film is smaller
than that of the selected portion of the film.
(-2-) The total misalignment of the edges of the x-ray
field with the respective edges of the selected portion of the image
receptor along the length or width dimensions of the x-ray field in
the plane of the image receptor shall not exceed 3.0 percent of the
SID when adjusted for full coverage of the selected portion of the
image receptor.
(-3-) The sum, without regard to sign of the misalignment
along any two orthogonal dimensions, shall not exceed 4.0 percent
of the SID.
(-b-) The center of the x-ray field in the plane of
the film shall be aligned with the center of the selected portion
of the film to within 2.0 percent of the SID.
(B) Activation of the fluoroscopic tube. X-ray production
in the fluoroscopic mode shall be controlled by a device that requires
continuous pressure by the fluoroscopist for the entire time of the
exposure (continuous pressure type switch). When recording serial
fluoroscopic images, the fluoroscopist shall be able to terminate
the x-ray exposures at any time but means may be provided to permit
completion of any single exposure of the series in process.
(C) Control of scattered radiation.
(i) Fluoroscopic configuration, including fluoroscopic
table designs, shall not permit any portion of any individual's body,
except the head, neck, and extremities, to be exposed to scattered
radiation emanating from above or below the tabletop unless the radiation
has passed through not less than a total of 0.25 mm lead equivalent
material. The material may be drapes, self-supporting curtains, or
viewing shields, in addition to any lead equivalency provided by a
protective apron.
(ii) Where sterile fields or special procedures prohibit
the use of normal protective barriers or drapes, all of the following
conditions shall be met.
(I) All persons in the room where fluoroscopy is performed
shall wear protective aprons that provide a shielding equivalent of
0.35 mm of lead.
(II) The fluoroscopic field size shall be reduced to
the absolute minimum required for the procedure being performed (area
of clinical interest).
(III) Operating and safety procedures shall reflect
the above conditions, and fluoroscopy personnel shall exhibit awareness
of situations requiring the use or nonuse of the protective drapes.
(iii) For image-intensified fluoroscopic radiation
machines with only a manual mode of collimation, the x-ray field produced
shall be limited to the area of the spot-film cassette at 40cm above
tabletop. Additionally, during fluoroscopy, the beam shall be restricted
to the area of the input phosphor.
(7) Additional requirements for CT radiation machines.
(A) Warning Label. Each registrant shall ensure that
each radiation machine is labeled in a conspicuous manner that cautions
individuals that radiation is produced when it is energized. This
label shall be affixed in a clearly visible location on the face of
the control unit.
(B) Indicated technique factors. The indicated technique
factors shall be accurate to meet manufacturer's specifications. If
these specifications are not available from the manufacturer, the
factors shall be accurate to within plus or minus 10 percent of the
indicated setting.
(C) Tomographic plane indication and alignment.
(i) 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.
(ii) For any multiple slice tomogram system, means
shall be provided to permit visual determination of the location of
a reference plane. The reference plane can be offset from the location
of the tomographic planes.
(iii) If a device using a light source is used to satisfy
the requirements of clause (i) or (ii) of this subparagraph, the light
source shall provide illumination levels sufficient to permit visual
determination of the location of the tomographic plane or reference
plane under ambient light conditions of up to 500 lux.
(D) Initiation of operation.
(i) The x-ray control and gantry shall provide visual
indication whenever x-rays are produced and, if applicable, whether
the shutter is open or closed.
(ii) Means shall be provided to require operator initiation
of each individual scan or series of scans.
(iii) All emergency buttons/switches shall be clearly
labeled as to their functions.
(E) Termination of exposure.
(i) Means shall be provided to terminate the x-ray
exposure automatically by either de-energizing the x-ray source or
shuttering the x-ray beam in the event of radiation machine 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
that monitor radiation machine function.
(ii) A signal visible to the operator shall indicate
when the x-ray exposure has been terminated through the means required
by clause (i) of this subparagraph.
(iii) The operator shall be able to terminate the x-ray
exposure at any time during a scan or series of scans under CT radiation
machines control of greater than 0.5 seconds duration. Termination
of the x-ray exposure shall necessitate resetting of the CT conditions
of operation before initiation of another scan.
(8) Additional requirements for therapeutic radiation
machines, simulators and electronic brachytherapy devices.
(A) General requirements.
Cont'd... |
