Current through Bulletin 2024-06, March 15, 2024
All fluoroscopic x-ray systems used shall be image
intensified and meet the following requirements:
(1) Primary barrier.
(a) The fluoroscopic imaging assembly shall
be provided with a primary protective barrier which intercepts the entire cross
section of the useful beam at SIDs for which the unit was designed.
(b) The x-ray tube used for fluoroscopy shall
not produce x-rays unless the barrier is in position to intercept the entire
useful beam.
(2)
Fluoroscopic beam limitation.
(a) For
certified fluoroscopic systems with or without a spot film device 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 of the SID. The sum of the excess length and the excess width shall be
no greater than four percent of the SID.
(b) For uncertified fluoroscopic systems with
a spot film device, the x-ray beam with the shutters fully open, during
fluoroscopy or spot filming, shall be no larger than the largest image receptor
size for which the device is designed. Measurements shall be made at the
minimum SID available but at no less than 20 centimeters table top to the film
plane distance.
(c) For uncertified
fluoroscopic systems without a spot film device, the requirements of
R313-28-40(1) apply.
(d) Other
requirements for fluoroscopic beam limitation:
(i) means shall be provided to permit further
limitation of the field. Beam-limiting devices manufactured after May 22, 1979,
and incorporated in equipment with a variable SID or visible area of greater
than 300 square centimeters shall be provided with means for stepless
adjustment of the x-ray field;
(ii)
equipment with a fixed SID and a visible area of 300 square centimeters or less
shall be provided with either stepless adjustment of the x-ray field or with
means to further limit the x-ray field size at the plane of the image receptor
to 125 square centimeters or less;
(iii) if provided, stepless adjustment shall
at the greatest SID, provide continuous field sizes from the maximum attainable
to a field size of five centimeters by five centimeters or less;
(iv) for equipment manufactured after
February 25, 1978, when the angle between the image receptor and beam axis is
variable, means shall be provided to indicate when the axis of the x-ray beam
is perpendicular to the plane of the image receptor; and
(v) for non-circular 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 which pass through the center of
the visible area of the image receptor.
(3) Spot-film beam limitation. Spot-film
devices shall meet the following requirements:
(a) means shall be provided between the
source and the patient for adjustment of the x-ray field size in the plane of
the film to the size of that portion of the film which has been selected on the
spot film selector. Adjustments 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. For spot film devices manufactured after June 21,
1979, if the x-ray field size is less than the size of the selected portion of
the film, the means for adjustment of the field size shall be only at the
operator's option;
(b) neither the
length nor the width of the x-ray field in the plane of the image receptor
shall differ from the corresponding dimensions of the selected portion of the
image receptor by more than three percent of the SID when adjusted for full
coverage of the selected portion of the image receptor. The sum, without regard
to sign, of the length and width differences shall not exceed four percent of
the SID;
(c) it shall be possible
to adjust the x-ray field size in the plane of the film to a size smaller than
the selected portion of the film. The minimum field size at the greatest SID
shall be equal to, or less than, five by five centimeters;
(d) 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 two percent of the SID; and
(e) on spot film devices manufactured after
February 25, 1978, if the angle between the plane of the image receptor and
beam axis is variable, means shall be provided to indicate when the axis of the
x-ray beam is perpendicular to the plane of the image receptor, and compliance
shall be determined with the beam axis indicated to be perpendicular to the
plane of the image receptor.
(4) Override. If a means exists to override
the automatic x-ray field size adjustments required in R313-28-40(2) and (3),
that means:
(a) shall be designed for use
only in the event of system failure;
(b) shall incorporate a signal visible at the
fluoroscopist's position which will indicate whenever the automatic field size
adjustment is overridden; and
(c)
shall be clearly and durably labeled as follows: FOR X-RAY FIELD LIMITATION
SYSTEM FAILURE.
(5)
Activation of the fluoroscopic tube. X-ray production in the fluoroscopic mode
shall be controlled by a dead-man switch. When recording serial fluoroscopic
images, the fluoroscopist shall be able to terminate the x-ray exposure
immediately, but means may be provided to permit completion of a single
exposure of the series in process.
(6) Entrance EXPOSURE rate allowable limits.
(a) For fluoroscopic equipment manufactured
before May 19, 1995, the following requirements apply:
(i) fluoroscopic equipment which is provided
with automatic exposure rate control shall not be operable at combinations of
tube potential and current which will result in an EXPOSURE rate in excess of
2.58 mC/kg (ten roentgens) per minute at the point where the center of the
useful beam enters the patient, except:
(A)
during recording of fluoroscopic images, or
(B) when an optional high level control is
provided. When so provided, the equipment shall not be operable at combinations
of tube potential and current which will result in an EXPOSURE rate in excess
of 1.29 mC/kg (five roentgens) per minute at the point where the center of the
useful beam enters the patient unless the high level control is activated.
Special means of activation of high level controls shall be required. The high
level control shall be operable only when continuous manual activation is
provided by the operator. A continuous signal audible to the fluoroscopist
shall indicate that the high level control is being employed.
(ii) fluoroscopic equipment which
is not provided with automatic exposure rate control shall not be operable at
combinations of tube potential and current which will result in a EXPOSURE rate
in excess of 1.29 mC/kg (five roentgens) per minute at the point where the
center of the useful beam enters the patient, except:
(A) during recording of fluoroscopic images,
or
(B) when an optional high level
control is activated. Special means of activation of high level controls shall
be required. The high level control shall be operable only when continuous
manual activation is provided by the operator. A continuous signal audible to
the fluoroscopist shall indicate that the high level control is being
employed.
(iii)
fluoroscopic equipment which is provided with both automatic exposure rate
control and a manual mode shall not be operable at combinations of tube
potential and current that will result in an exposure rate of 2.58 mC/kg (ten
roentgens) per minute in either mode at the point where the center of the
useful beam enters the patient except:
(A)
during recording of fluoroscopic images, or
(B) when an optional high level control is
provided. When so provided, the equipment shall not be operable at combinations
of tube potential and current which will result in an EXPOSURE rate in excess
of 1.29 mC/kg (five roentgens) per minute at the point where the center of the
useful beam enters the patient unless the high level control is activated.
Special means of activation of high level controls shall be required. The high
level control shall be operable only when continuous manual activation is
provided by the operator. A continuous signal audible to the fluoroscopist
shall indicate that the high level control is being employed.
(b) For fluoroscopic
equipment manufactured on and after May 19, 1995, the following requirements
apply:
(i) fluoroscopic equipment operable at
combinations of tube potential and current which will result in an EXPOSURE
rate greater than 1.29 mC/kg (five roentgens) per minute at the point where the
center of the useful beam enters the patient shall be equipped with automatic
exposure rate control. Provision for manual selection of technique factors may
be provided.
(ii) fluoroscopic
equipment shall not be operable at combinations of tube potential and current
which will result in an EXPOSURE rate in excess of 2.58 mC/kg (ten roentgens)
per minute at the point where the center of the useful beam enters the patient
except:
(A) during recording of images from
an x-ray image-intensifier tube using photographic film or a video camera when
the x-ray source is operated in pulsed mode, or
(B) when an optional high level control is
activated. When the high level control is activated, the equipment shall not be
operable at combinations of tube potential and current which will result in an
EXPOSURE rate in excess of 5.16 mC/kg (20 roentgens) per minute at the point
where the center of the useful beam enters the patient. Special means of
activation of high level controls shall be required. The high level control
shall be operable only when continuous manual activation is provided by the
operator. A continuous signal audible to the fluoroscopist shall indicate that
the high level control is being employed.
(c) Compliance with the requirements of
R313-28-40(6) shall be determined as follows:
(i) if the source is below the x-ray table,
the EXPOSURE rate shall be measured one centimeter above the tabletop or
cradle;
(ii) if the source is above
the x-ray table, the EXPOSURE rate shall be measured at 30 centimeters above
the tabletop with the end of the beam-limiting device or spacer positioned as
closely as possible to the point of measurement;
(iii) for 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 available SID's,
provided that the end of the beam-limiting device or spacer is no closer than
30 centimeters from the input surface of the fluoroscopic imaging assembly;
or
(iv) for a lateral type
fluoroscope, the exposure rate shall be measured at a point 15 centimeters 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 close as possible
to the point of measurement. If the tabletop is movable, it shall be positioned
as close 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 x-ray
table.
(d) Fluoroscopic
radiation therapy simulation systems are exempt from the requirements of
R313-28-40(6).
(7)
Measurement of entrance EXPOSURE rates shall be performed for both maximum and
typical values as follows:
(a) measurements
shall be made annually or after maintenance of the system which might affect
the EXPOSURE rate;
(b) results of
these measurements shall be posted where the fluoroscopist may have ready
access to the results while using the fluoroscope and in the record required in
R313-28-31(3)(b).
The measurement results shall be stated in roentgens per minute and include the
machine settings used in determining results. The name of the person performing
the measurements and the date the measurements were performed shall be included
in the results;
(c) conditions of
the annual measurement of maximum entrance EXPOSURE rate shall be performed as
follows:
(i) the measurement shall be made
under the conditions that satisfy the requirements of
R313-28-40(6)(c);
(ii) the kVp, mA,
and other selectable parameters shall be adjusted to those settings which give
the maximum entrance EXPOSURE rate; and
(iii) x-ray systems that incorporate
automatic exposure rate control shall have sufficient attenuative material
placed in the useful beam to produce the maximum output of that system;
and
(d) conditions of
the annual measurement of typical entrance EXPOSURE rate are as follows:
(i) the measurement shall be made under the
conditions that satisfy the requirements of R313-28-40(6)(c);
(ii) the kVp, mA, and other selectable
parameters shall be those settings typical of clinical use of the x-ray system;
and
(iii) the x-ray system that
incorporates automatic EXPOSURE rate control shall have an appropriate phantom
placed in the useful beam to produce a milliamperage and kilovoltage typical of
the use of the x-ray system.
(8) 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 0.516 uC/kg (two milliroentgens) per hour at ten
centimeters from accessible surfaces of the fluoroscopic imaging assembly
beyond the plane of the image receptor for each mC/kg (roentgen) per minute of
entrance EXPOSURE rate.
(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 tabletop, the measurement shall be made with the input surface of the
fluoroscopic imaging assembly positioned 30 centimeters 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
centimeters.
(iv) Movable grids and
compression devices shall be removed from the useful beam during the
measurement.
(9) Indication of potential and current.
During fluoroscopy and cinefluorography, x-ray tube potential and current shall
be continuously indicated.
(10)
Source-skin distance. The source to skin distance shall not be less than:
(a) 38 centimeters on stationary fluoroscopic
systems manufactured on or after August 1, 1974;
(b) 35.5 centimeters on stationary
fluoroscopic systems manufactured prior to August 1, 1974;
(c) 30 centimeters on all mobile
fluoroscopes; or
(d) 20 centimeters
for all mobile fluoroscopes when used for specific surgical
applications.
(11)
Fluoroscopic timer.
(a) Means shall be
provided to preset the cumulative on-time of the fluoroscopic x-ray 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. The signal shall continue to sound while x-rays are
produced until the timing device is reset.
(12) Control of scatter radiation.
(a) The tables of fluoroscopic assemblies
when combined with normal operating procedures shall provide protection from
scatter radiation so that unprotected parts of a staff or ancillary
individual's body shall not 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 not allow portions of a staff member's or ancillary
person's body, except the extremities, to be exposed to unattenuated scattered
radiation emanating from above the tabletop unless:
(i) the radiation has passed through not less
than 0.25 mm lead equivalent material including, but not limited to, drapes,
bucky-slot cover panel, or self supporting curtains, in addition to the lead
equivalency provided by the protective apron referred to in
R313-28-31(2)(d),
(ii) that individual is at least 120
centimeters from the center of the useful beam, or
(iii) it is not feasible to attach shielding
to special procedures equipment and personnel are wearing protective
aprons.
(13)
Spot film exposure reproducibility. Fluoroscopic systems equipped with
radiographic spot film mode shall meet the exposure reproducibility
requirements of
R313-28-54.
(14) Radiation therapy simulation systems.
Radiation therapy simulation systems shall be exempt from all the requirements
R313-28-40(1), (8), and (11) provided that:
(a) the systems are designed and used in such
a manner that no individual other than the patient is in the x-ray room during
periods of time when the system is producing x-rays; and
(b) the systems which do not meet the
requirements of R313-28-40(11) are provided with a means of indicating the
cumulative time that an individual patient has been exposed to x-rays.
Procedures shall require, in these cases, that the timer be reset between
examinations.