Current through Register Vol. 30, No. 38, September 20, 2024
A. Useful beam limitation. A registrant
shall:
1. Provide beam-limiting devices that
restrict the entire cross section of the useful beam to less than the area of
the primary barrier at any Source-to-Image Receptor Distance (SID);
2. Ensure that the x-ray field size produced
by fluoroscopic systems without image intensification does not extend beyond
the visible area of the image receptor at any SID;
3. Ensure that the x-ray field size produced
by fluoroscopic systems with image intensification and automatic shutter
control does not exceed the diameter of the image receptor at any
SID;
4. Ensure that the x-ray field
size produced by fluoroscopic systems with image intensification and manual
shutter control does not exceed the diameter of the image receptor with the
fluoroscopic imaging assembly positioned at the maximum usable distance above
the table top; and
5. Ensure that
the x-ray field size produced by fluoroscopic systems with image
intensification and manual shutter control, where the fluoroscopic tube is
above the table top, does not exceed the diameter of the image receptor with
the shutters open to the fullest extent, and at the maximum SID which the
fluoroscopic tube is capable of producing radiation.
B. Fluoroscopic primary protective barrier A
registrant shall:
1. Provide the fluoroscopic
imaging assembly with a primary protective barrier that always intercepts the
entire cross section of the useful beam at any SID.
2. Ensure that the fluoroscopic tube is not
capable of producing radiation unless the primary protective barrier is in a
position to intercept the entire cross section of the useful beam.
3. Ensure that fluoroscopic radiation
production automatically terminates if the primary protective barrier is
removed from the useful beam.
4.
Ensure that the fluoroscopic primary protective barrier meets the following
requirements for attenuation of the useful beam:
a. For equipment installed before November
15, 1967, the required lead equivalent of the barrier is not less than 1.5
millimeters for fluoroscopes that produce less than 100 kVp, 1.8 millimeters
for fluoroscopes that produce at least 100 kVp but less than 125 kVp, and 2.0
millimeters for fluoroscopes that produce 125 or more kVp. (For conventional
fluoroscopes, these requirements may be assumed to have been met if the
exposure rate measured at the viewing surface of the fluorescent screen does
not exceed 12.9 microcoulombs per kilogram (50 milliroentgens) per hour with
the screen in the primary beam of the fluoroscope without a patient, under
normal operating conditions.) For equipment installed or reinstalled, the
required lead equivalent of the barrier is 2.0 millimeters for fluoroscopes
that produce less than 125 kVp or 2.7 millimeters for fluoroscopes that produce
125 or more kVp.
b. For
fluoroscopic systems that use image intensification, the exposure rate, due to
transmission through the primary protective barrier, does not exceed 516 nC/kg
(2 milliroentgens) per hour at 10 centimeters (4 inches) from any accessible
surface of the fluoroscopic imaging assembly, beyond the plane of the image
receptor for each 258 µC/kg (1 roentgen) per minute of entrance exposure
rate.
c. Compliance with
subsections (B)(4)(a) and (b) is determined with the image receptor positioned
35.5 centimeters (14 inches) from the panel or table top, at normal operating
technical factors and with the attenuation block in the useful beam for systems
with image intensification.
C. Entrance exposure rate limits. A
registrant shall ensure that:
1. The exposure
rate, measured at the point where the center of the useful beam enters the
patient does not exceed 2.6 mC/kg (10 roentgens) per minute at any combination
of tube potential and current, except during recording of fluoroscopic images
or if provided with optional high-level control.
2. If provided with optional high-level
control, the equipment is not operable at any combination of tube potential and
current that will result in an exposure rate in excess of 2.6 mC/kg (10
roentgens) per minute at the point where the center of the useful beam enters
the patient, unless the high-level control is activated, in which case an
exposure rate in excess of 5.2 mC/kg (20 roentgens) per minute is prohibited.
a. Special means of activation of high-level
controls, such as additional pressure applied continuously by the operator, are
required to avoid accidental use.
b. A continuous signal audible to the
fluoroscopist is required to indicate that the high-level control is being
employed.
3. The
Department shall determine compliance with subsections (C)(1) and (2) as
follows:
a. Remove grids and compression
devices from the useful beam during the measurement;
b. If the source is below the table, measure
the exposure rate 1 centimeter above the table top or cradle; and
c. If the source is above the table, measure
the exposure rate 30 centimeters (11.8 inches) above the table top with the end
of the beam-limiting device or spacer positioned as closely as possible to the
point of measurement;
d. For
fluoroscopy involving a mobile C-arm x-ray system, measure the exposure rate 30
centimeters (11.8 inches) from the input surface of the fluoroscopic imaging
assembly;
e. For fluoroscopy
involving a C-arm x-ray system, measure the exposure rate 30 centimeters (11.8
inches) from the input surface of the fluoroscope imaging assembly, with the
x-ray source positioned at any available SID, provided that the end of the
beam-limiting device or spacer is not closer than 30 centimeters (11.8 inches)
from the input surface of the fluoroscopic image assembly; and
f. For a lateral fluoroscope, measure the
exposure rate 15 centimeters (5.9 inches) 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 (5.9 inches) to the centerline
of the x-ray table.
D. The registrant shall ensure that the
source-to-skin distance is not less than:
1.
38 centimeters (15 inches) on stationary fluoroscopes installed after January
2, 1996;
2. 35.5 centimeters (14
inches) on stationary fluoroscopes which are in operation before January 2,
1996;
3. 30 centimeters (11.8
inches) on all mobile fluoroscopes; and
4. 20 centimeters (8 inches) for
image-intensified fluoroscopes used for a specific surgical application. The
registrant shall follow any precautionary measures in the users operating
manual.
E. Each
fluoroscopic system installation is subject to all of the following
requirements for the control of stray radiation. A registrant shall:
1. Provide a shielding device of at least
0.25 millimeter lead equivalent for covering the Bucky-slot during
fluoroscopy;
2. Except for
fluoroscopy performed using portable or mobile C-arm x-ray systems or during
surgical procedures or cardiac catheterization, provide protective drapes, or
hinged or sliding panels of at least 0.25 millimeters lead equivalent, between
the patient and fluoroscopist to intercept scattered radiation that would
otherwise reach the fluoroscopist and others near the machine, but not
substitute drapes and panels for a protective apron; and
3. Ensure that protective aprons of at least
0.25 millimeter lead equivalent are worn in the fluoroscopy room by each
person, except the patient, whose body is likely to be exposed to 50 µSv/hr (5
mR/hr) or more.
F.
Exposure control. A registrant shall:
1.
Ensure that activation of the fluoroscopic tube is controlled by a "dead-man"
switch;
2. Provide a manual reset
cumulative timing device, which is activated only during production of
radiation in the fluoroscopic mode, to indicate elapsed time by an audible
signal or terminate production of radiation;
3. Provide a device for exposure control in
the "spot film" mode that terminates exposure either automatically, or after a
preset time interval, preset number of pulses, preset product of current and
time, or preset exposure; and
4.
Ensure that the x-ray tube potential and current are continuously
indicated.
G. A
registrant shall provide systems used for mobile fluoroscopy with image
intensification.
H. Fluoroscopic
treatment simulators. Simulators are exempt from subsections (A) through (G). A
registrant shall:
1. Use a beam limiting
device that restricts the beam to the area of clinical interest.
2. Include and label devices for settings or
physical factors, such as kVp, mA, or exposure time on the control
panel;
3. Ensure that the
fluoroscopic exposure switch or switches are of the "deadman" type;
4. Ensure that each person whose presence is
necessary is in the simulator room during exposure and protected with a lead
apron of at least 0.5 millimeter lead equivalent or a portable shield. Any
person who places their hands in the useful x-ray beam shall wear leaded
gloves; and
5. Ensure that the
operator stands behind a barrier and is able to observe the patient during
simulator exposures.