WAC 246-225-050
Fluoroscopic X-ray systems. Fluoroscopic X-ray systems shall meet the following
requirements:
(1) Limitation of useful beam.
(a) The fluoroscopic tube shall not produce X rays unless
the primary barrier is in position to intercept the entire
useful beam at all times.
(b) The entire cross section of the useful beam shall be
intercepted by the primary protective barrier of the
fluoroscopic image assembly at any source-to-image-distance
(SID).
(c) Nonimage-intensified fluoroscopic equipment shall not
be used.
(d) For fluoroscopic equipment without a spot film
device, neither the length nor the width of the fluoroscopic
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 of the SID. The sum of the excess length and
the excess width shall be no greater than four percent of the
SID. Measurements shall be made at the minimum SID available
but at no less than 20 centimeters (8 inches) table top to
image receptor distance.
(e) For uncertified fluoroscopic equipment with a spot
film device, the fluoroscopic X-ray beam with the shutters
wide open (during either fluoroscopy itself or spot films)
shall be no larger than the dimensions of the largest spot
film size for which the device is designed. Measurements
shall be made at the minimum SID available, but at no less
than 20 centimeters (8 inches) table top to the film plane
distance.
(f) For certified (21 CFR 1020) fluoroscopic equipment
with a spot film device, neither the length nor the width of
the fluoroscopic 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 of the SID. The sum of
the excess length and width shall be no greater than four
percent of the SID. Measurements shall be made at the minimum
SID available, but at no less than 20 centimeters (8 inches)
table top to film plane distance.
(g) Fluoroscopic equipment beam limitation:
(i) Means shall be provided to reduce the beam size at
the plane of the image receptor to 125 square centimeters or
less; and
(ii) The minimum field size at the greatest SID shall be
equal to or less than 5 centimeters by 5 centimeters.
(2) Activation of the fluoroscopic tube. X-ray
production in the fluoroscopic mode shall be controlled by a
deadman switch.
(3) Entrance exposure rate allowable limits.
(a) For equipment with or without automatic brightness
control, the exposure rate measured at the point where the
center of the useful beam enters the patient shall not exceed
2.58 x 10-3 coulombs per kilogram per minute (ten roentgens per
minute), except during film recording of fluoroscopic images
or when an optional high level control (HLC) is activated.
(b) For equipment provided with HLC, the equipment shall
not be operable at a combination of tube potential and current
which will result in an exposure rate in excess of 1.29 x 10-3
coulombs per kilogram per minute (5 roentgens per minute) at
the point where the center of the useful beam enters the
patient, unless the HLC is activated.
(i) Special means of activation of high level controls,
such as additional pressure applied continuously by the
operator, shall be required to avoid accidental use.
(ii) A continuous signal audible to the fluoroscopist
shall indicate the high level control is employed.
(c) Measuring compliance of entrance exposure rate
limits. Compliance with subsection (3) of this section shall
be determined as follows:
(i) Movable grids and compression devices shall be
removed from the useful beam during the measurement;
(ii) If the source is below the table, exposure rate
shall be measured 1 centimeter above the table top or cradle;
(iii) If the source is above the table, the exposure rate
shall be measured at 30 centimeters above the table top with
the end of the beam-limiting device or spacer positioned as
closely as possible to the point of measurement;
(iv) In a C-arm type of fluoroscope, the exposure rate
shall be measured 30 centimeters from the input surface of the
fluoroscopic imaging assembly, with the source positioned at
any available SID, provided the end of the beam-limiting
device or spacer is no closer than 30 centimeters from the
input surface of fluoroscopic imaging assembly; and
(v) In a lateral-type fluoroscope, the exposure rate
shall be measured at a point 15 centimeters from the center
line of the X-ray table with the end of the beam-limiting
device or spacer positioned as closely as possible to the
point of measurement. If the table top is movable, the table
top 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 to the center line of the
X-ray table.
(d) Periodic measurement of entrance exposure rate
limits.
(i) Periodic measurements of the exposure rate shall be
made. An adequate period for such measurements shall be
annually or after maintenance of the system affecting the
exposure rate.
(ii) Results of exposure rate measurements shall be
available where the fluoroscopist has ready access to the
measurements while using that fluoroscope. Results of the
measurements shall include:
(A) The maximum possible coulombs per kilogram per minute
(R/minute), as well as the technique factors associated with
it;
(B) The name of the person performing the measurements;
(C) The last date the measurements were performed; and
(D) The type of device used in making the measurements.
(iii) Conditions of measurement:
(A) The kVp shall be adjusted to that which will produce
the maximum entrance exposure rate;
(B) The high level control, if present, shall not be
activated;
(C) The X-ray systems that incorporate automatic exposure
rate control (automatic brightness control) shall have
sufficient material, for example, lead or lead equivalence,
placed in the useful beam to produce the maximum output of the
X-ray system; and
(D) X-ray systems not incorporating automatic exposure
rate control shall utilize whatever combination of kVp, mA,
and other selectable parameters that will generate the highest
exposure rate of the X-ray system. Materials, for example, an
attenuation block, may be placed in the useful beam to protect
the imaging system, as long as the material does not affect
the measurement of the exposure rate.
(4) Barrier transmitted radiation rate limits.
(a) 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 5.16 x 10-7 coulombs
per kilogram per hour (2 milliroentgens per hour) for each
2.58 x 10-4 coulombs per kilogram per minute (roentgen per
minute) of entrance exposure rate. The barrier transmission
measurement shall be made at 10 centimeters from an accessible
surface of the fluoroscopic imaging assembly beyond the plane
of the image receptor.
(b) Measuring compliance of barrier transmission.
(i) The exposure rate due to transmission through the
primary protective barrier combined with radiation from the
image intensifier shall be determined by measurements averaged
over an area of 100 square centimeters with no linear
dimension greater than 20 centimeters.
(ii) If the source is below the table top, the
measurement shall be made with the input surface of the
fluoroscopic imaging assembly positioned 30 centimeters above
the table top.
(iii) If the source is above the table top and the SID is
variable, the measurement shall be made with the end of the
beam-limiting device or spacer as close to the table top as it
can be placed, provided the beam-limiting device or spacer
shall not be closer than 30 centimeters.
(iv) Movable grids and compression devices shall be
removed from the useful beam during the measurement.
(5) Indication of potential and current. During
fluoroscopy and cinefluorography, X-ray tube potential and
current shall be continuously indicated.
(6) Source-skin distance (SSD). The source to skin
distance shall not be less than:
(a) 38 centimeters on stationary fluoroscopes;
(b) 30 centimeters on mobile fluoroscopes; and
(c) 20 centimeters for image intensified fluoroscopes
used for specific surgical application. The user must provide
precautionary measures for the use of the fluoroscope due to
its short SSD.
(7) Fluoroscopic timer.
(a) Means shall be provided to preset the cumulative
on-time of the fluoroscopic tube. The maximum cumulative time
of the timing device shall not exceed five minutes without
resetting.
(b) A signal audible to the fluoroscopist shall indicate
the completion of a preset cumulative on-time. Such signal
shall continue to sound while X rays are produced until the
timing device is reset. Alternatively, the timing device may
terminate exposures at the end of the preset time.
(c) Total fluoroscopic on-time for each patient shall be
recorded, either in patient's chart or in a separate log.
(8) Control of scattered radiation.
(a) Fluoroscopic table designs when combined with normal
operating procedures shall be such that no unprotected part of
staff or ancillary person'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 mm lead equivalent.
(b) Equipment configuration when combined with procedures
shall be such that no portion of staff or ancillary person's
body, except the extremities, shall be exposed to the
unattenuated scattered radiation emanating from above the
table top unless:
(i) The radiation has passed through not less than 0.25
mm lead equivalent material, for example, drapes, Bucky-slot
cover-sliding or folding panel, or self-supporting curtains,
in addition to lead equivalency provided by the protective
apron referred to under WAC 246-225-020 (2)(e); and
(ii) Exceptions to subdivision (b) of this subsection may
be made in some special procedures where a sterile field will
not permit the use of the normal protective barriers. Where
the use of prefitted sterilized covers for the barriers is
practical, the department shall not permit such exception.
(9) Radiation therapy simulation systems. Radiation
therapy simulation systems shall be exempt from the
requirements of subsection (3) of this section. In addition,
these systems shall be exempt from:
(a) Subsections (1) and (4) of this section provided such
systems are designed and used in such a manner that no
individual other than the patient is in the X-ray room when
the system is producing X rays; and
(b) Subsection (7) of this section if such systems are
provided with a means of indicating the cumulative time that
an individual patient has been exposed to X rays.
[Statutory Authority: RCW 70.98.050. 94-01-073, §
246-225-050, filed 12/9/93, effective 1/9/94. Statutory
Authority: RCW 70.98.050 and 70.98.080. 91-15-083 (Order
183), § 246-225-050, filed 7/23/91, effective 8/23/91. Statutory Authority: RCW 43.70.040. 91-02-049 (Order 121),
recodified as § 246-225-050, filed 12/27/90, effective
1/31/91. Statutory Authority: RCW 70.98.080. 87-01-031
(Order 2450), § 402-28-040, filed 12/11/86; 83-19-050 (Order
2026), § 402-28-040, filed 9/16/83. Statutory Authority: RCW 70.98.050. 81-01-011 (Order 1570), § 402-28-040, filed
12/8/80; Order 1084, § 402-28-040, filed 1/14/76; Order 1, §
402-28-040, filed 1/8/69; Rules (part), filed 10/26/66.]