| (II) If the source is above the x-ray table, the exposure
rate (air kerma rate) shall be measured at 30 cm above the tabletop
with the end of the beam-limiting device or spacer positioned as closely
as possible to the point of measurement.
(III) In a C-arm fluoroscopic system, the exposure
rate (air kerma rate) shall be measured at 30 cm from the input surface
of the fluoroscopic imaging assembly provided that the end of the
beam-limiting device or spacer is no closer than 30 cm from the input
surface of the fluoroscopic imaging assembly. The applicable limit
shall not be exceeded at any available SID.
(IV) In a lateral (horizontal) fluoroscopic system,
the exposure rate (air kerma rate) shall be measured at a point 15
cm 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 table top 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 cm to the centerline of the x-ray table.
(B) The following requirements apply to fluoroscopic
systems manufactured on or after May 19, 1995.
(i) Fluoroscopic systems operable at any combination
of tube potential and current that will result in an exposure rate
(air kerma rate) greater than 1.29 x 10-3 C/kg/min
(5 R/min or 50 mGy/min) at the point where the center of the useful
beam enters the patient shall be equipped with AERC. Provision for
manual selection of technique factors may be provided.
(ii) Fluoroscopic systems shall not be operable at
any combination of tube potential and current that will result in
an exposure rate (air kerma rate) in excess of 2.58 x 10-3 C/kg/min (10 R/min or 100 mGy/min) at the
point where the center of the useful beam enters the patient except:
(I) for fluoroscopic systems manufactured prior to
June 10, 2006, during the 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 a pulsed mode;
(II) for fluoroscopic systems manufactured on and after
June 10, 2006, during the recording of images from the x-ray image-intensifier
to provide the user with a recorded image(s) after termination of
the exposure. Such recording does not include images resulting from
a last-image-hold feature that are not recorded; and
(III) when the high-level control is activated, the
fluoroscopic system shall not be operable at any combination of tube
potential and current that will result in an exposure rate (air kerma
rate) in excess of 5.16 x 10-3 C/kg/min
(20 R/min or 200 mGy/min) 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 only be operable
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) Measuring compliance of entrance exposure rate
(air-kerma rate) for fluoroscopic systems shall be determined as follows.
(I) If the source is below the x-ray table, the exposure
rate (air kerma rate) shall be measured at 1 cm above the tabletop
or cradle.
(II) If the source is above the x-ray table, the exposure
rate (air kerma rate) shall be measured at 30 cm above the tabletop
with the end of the beam-limiting device or spacer positioned as closely
as possible to the point of measurement.
(III) In a C-arm fluoroscopic system, the exposure
rate (air kerma rate) shall be measured at 30 cm from the input surface
of the fluoroscopic imaging assembly provided that the end of the
beam-limiting device or spacer is no closer than 30 cm from the input
surface of the fluoroscopic imaging assembly. The applicable limit
shall not be exceeded at any available SID.
(IV) In a lateral (horizontal) fluoroscopic system,
the exposure rate (air kerma rate) shall be measured at a point 15
cm 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 table top 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 cm to the centerline of the x-ray table.
(C) For hand-held fluoroscopic systems, the exposure
rate (air kerma rate) shall be measured at the point closest to the
source.
(D) Periodic measurement of entrance exposure rate
(air kerma rate) for fluoroscopic systems shall be performed as follows
by a licensed medical physicist.
(i) Such measurements shall be made within 30 days
of installation and within 30 days after any maintenance of the system
that might affect the exposure rate. Thereafter, the measurements
shall be made annually or at intervals not to exceed 14 months from
the date of the prior measurements.
(ii) Results of these measurements shall be posted
where any fluoroscopist may have ready access to such results while
using the fluoroscopic system and maintained in accordance with subsection
(s)(1) of this section for inspection by the agency. The measurement
results shall be stated in R/min or mGy/min and include the technique
factors used in determining such results. The name of the person performing
the measurements and the date the measurements were performed shall
be included in the results.
(iii) Conditions of periodic measurement of entrance
exposure rate (air kerma rate) are as follows.
(I) The measurement shall be made in accordance with
subparagraph (A)(iv) or (B)(iii) of this paragraph, as applicable.
(II) Fluoroscopic systems that do not incorporate an
AERC shall utilize a milliamperage and kVp typical of the clinical
use of the fluoroscopic system. Materials should be placed in the
useful beam between the detection and imaging systems when conducting
these periodic measurements to protect the imaging system.
(III) Fluoroscopic systems that do incorporate an AERC
shall have sufficient material placed in the useful beam to produce
a milliamperage and kVp typical of the clinical use of the fluoroscopic
system.
(4) Measurements of the output rate for fluoroscopic
systems. Measurements of the output rate of the fluoroscopic system
shall be performed with a calibrated dosimetry system in accordance
with subsection (i)(14) of this section.
(5) Indication of potential and current. During fluoroscopy
and cinefluorography, the kV and the mA shall be continuously indicated
at the control panel and/or the fluoroscopist's position.
(6) Source-to-skin distance (SSD).
(A) Means shall be provided to limit the SSD to the
following:
(i) not less than 38 cm on stationary fluoroscopic
systems; and
(ii) not less than 30 cm on portable fluoroscopic systems.
(B) For image-intensified fluoroscopic systems intended
for specific surgical application that would be prohibited at the
SSDs specified in subparagraph (A) of this paragraph, provisions may
be made for operation at shorter SSDs, but in no case less than 20
cm.
(C) For stationary or portable C-arm fluoroscopic systems
manufactured on or after June 10, 2006, having a maximum source-to-image
receptor distance of less than 45 cm, the following requirements shall
be met.
(i) Means shall be provided to limit the SSD to not
less than 19 cm.
(ii) Such systems will be labeled and used for extremity
use only.
(iii) For those systems intended for specific surgical
applications that would be prohibited at the SSD specified in clause
(i) of this subparagraph, provisions may be made for operation at
a shorter SSD, but in no case less than 10 cm.
(D) The registrant's written operating and safety procedures
shall provide precautionary measures to be adhered to during the use
of the shorter SSD, in accordance with manufacturer's precautions,
if provided.
(E) The SSD shall not be less than the FDA approved
variance for a specific manufacturer of a hand-held fluoroscope.
(7) Fluoroscopic system timer and display.
(A) Fluoroscopic systems manufactured prior to June
10, 2006 shall comply with the following requirements.
(i) 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 5 minutes without resetting.
Cont'd... |
