[Code of Federal Regulations]
[Title 21, Volume 8]
[Revised as of April 1, 2008]
From the U.S. Government Printing Office via GPO Access
[CITE: 21CFR1020.32]
[Page 641-646]
TITLE 21--FOOD AND DRUGS
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN
SERVICES (CONTINUED)
PART 1020_PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING
PRODUCTS--Table of Contents
Sec. 1020.32 Fluoroscopic equipment.
The provisions of this section apply to equipment for fluoroscopic
imaging or for recording images from the fluoroscopic image receptor,
except computed tomography x-ray systems manufactured on or after
November 29, 1984.
(a) Primary protective barrier--(1) Limitation of useful beam. The
fluoroscopic imaging assembly shall be provided with a primary
protective barrier which intercepts the entire cross section of the
useful beam at any SID. The x-ray tube used for fluoroscopy shall not
produce x-rays unless the barrier is
[[Page 642]]
in position to intercept the entire useful beam. The AKR due to
transmission through the barrier with the attenuation block in the
useful beam combined with radiation from the fluoroscopic image receptor
shall not exceed 3.34x10-3 percent of the entrance AKR, at a
distance of 10 cm from any accessible surface of the fluoroscopic
imaging assembly beyond the plane of the image receptor. Radiation
therapy simulation systems shall be exempt from this requirement
provided the systems are intended only for remote control operation and
the manufacturer sets forth instructions for assemblers with respect to
control location as part of the information required in Sec.
1020.30(g). Additionally, the manufacturer shall provide to users, under
Sec. 1020.30(h)(1)(i), precautions concerning the importance of remote
control operation.
(2) Measuring compliance. The AKR shall be measured in accordance
with paragraph (d) of this section. The AKR due to transmission through
the primary barrier combined with radiation from the fluoroscopic image
receptor shall be determined by measurements averaged over an area of
100 square cm with no linear dimension greater than 20 cm. 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. 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. Movable grids and compression devices
shall be removed from the useful beam during the measurement. For all
measurements, the attenuation block shall be positioned in the useful
beam 10 cm from the point of measurement of entrance AKR and between
this point and the input surface of the fluoroscopic imaging assembly.
(b) Field limitation--(1) Angulation. For fluoroscopic equipment
manufactured after February 25, 1978, when the angle between the image
receptor and the beam axis of the x-ray beam 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. Compliance with paragraphs (b)(4) and
(b)(5) of this section shall be determined with the beam axis indicated
to be perpendicular to the plane of the image receptor.
(2) Further means for limitation. Means shall be provided to permit
further limitation of the x-ray field to sizes smaller than the limits
of paragraphs (b)(4) and (b)(5). Beam-limiting devices manufactured
after May 22, 1979, and incorporated in equipment with a variable SID
and/or the capability of a visible area of greater than 300 square cm,
shall be provided with means for stepless adjustment of the x-ray field.
Equipment with a fixed SID and the capability of a visible area of no
greater than 300 square cm shall be provided with either stepless
adjustment of the x-ray field or with a means to further limit the x-ray
field size at the plane of the image receptor to 125 square cm or less.
Stepless adjustment shall, at the greatest SID, provide continuous field
sizes from the maximum obtainable to a field size containable in a
square of 5 cm by 5 cm. This paragraph does not apply to non-image-
intensified fluoroscopy.
(3) Non-image-intensified fluoroscopy. The x-ray field produced by
non-image-intensified fluoroscopic equipment shall not extend beyond the
entire visible area of the image receptor. Means shall be provided for
stepless adjustment of field size. The minimum field size, at the
greatest SID, shall be containable in a square of 5 cm by 5 cm.
(4) Fluoroscopy and radiography using the fluoroscopic imaging
assembly with inherently circular image receptors. (i) For fluoroscopic
equipment manufactured before June 10, 2006, other than radiation
therapy simulation systems, the following applies:
(A) 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 percent of the SID. The sum of the excess length
and the excess width shall be no greater than 4 percent of the SID.
(B) For rectangular x-ray fields used with circular image receptors,
the error in alignment shall be determined along the length and width
dimensions
[[Page 643]]
of the x-ray field which pass through the center of the visible area of
the image receptor.
(ii) For fluoroscopic equipment manufactured on or after June 10,
2006, other than radiation therapy simulation systems, the maximum area
of the x-ray field in the plane of the image receptor shall conform with
one of the following requirements:
(A) When any linear dimension of the visible area of the image
receptor measured through the center of the visible area is less than or
equal to 34 cm in any direction, at least 80 percent of the area of the
x-ray field overlaps the visible area of the image receptor, or
(B) When any linear dimension of the visible area of the image
receptor measured through the center of the visible area is greater than
34 cm in any direction, the x-ray field measured along the direction of
greatest misalignment with the visible area of the image receptor does
not extend beyond the edge of the visible area of the image receptor by
more than 2 cm.
(5) Fluoroscopy and radiography using the fluoroscopic imaging
assembly with inherently rectangular image receptors. For x-ray systems
manufactured on or after June 10, 2006, the following applies:
(i) 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 percent of the SID. The sum of the excess length
and the excess width shall be no greater than 4 percent of the SID.
(ii) 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.
(6) Override capability. If the fluoroscopic x-ray field size is
adjusted automatically as the SID or image receptor size is changed, a
capability may be provided for overriding the automatic adjustment in
case of system failure. If it is so provided, a signal visible at the
fluoroscopist's position shall indicate whenever the automatic field
adjustment is overridden. Each such system failure override switch shall
be clearly labeled as follows:
For X-ray Field Limitation System Failure
(c) Activation of tube. X-ray production in the fluoroscopic mode
shall be controlled by a device which requires continuous pressure by
the operator for the entire time of any exposure. When recording serial
radiographic images from the fluoroscopic image receptor, the operator
shall be able to terminate the x-ray exposure(s) at any time, but means
may be provided to permit completion of any single exposure of the
series in process.
(d) Air kerma rates. For fluoroscopic equipment, the following
requirements apply:
(1) Fluoroscopic equipment manufactured before May 19, 1995--(i)
Equipment provided with automatic exposure rate control (AERC) shall not
be operable at any combination of tube potential and current that will
result in an AKR in excess of 88 mGy per minute (vice 10 R/min exposure
rate) at the measurement point specified in Sec. 1020.32(d)(3), except
as specified in Sec. 1020.32(d)(1)(v).
(ii) Equipment provided without AERC shall not be operable at any
combination of tube potential and current that will result in an AKR in
excess of 44 mGy per minute (vice 5 R/min exposure rate) at the
measurement point specified in Sec. 1020.32(d)(3), except as specified
in Sec. 1020.32(d)(1)(v).
(iii) Equipment provided with both an AERC mode and a manual mode
shall not be operable at any combination of tube potential and current
that will result in an AKR in excess of 88 mGy per minute (vice 10 R/min
exposure rate) in either mode at the measurement point specified in
Sec. 1020.32(d)(3), except as specified in Sec. 1020.32(d)(1)(v).
(iv) Equipment may be modified in accordance with Sec. 1020.30(q)
to comply with Sec. 1020.32(d)(2). When the equipment is modified, it
shall bear a label indicating the date of the modification and the
statement:
Modified to comply with 21 CFR 1020.32(h)(2).
(v) Exceptions:
(A) During recording of fluoroscopic images, or
(B) When a mode of operation has an optional high-level control, in
which case that mode shall not be operable at any combination of tube
potential and
[[Page 644]]
current that will result in an AKR in excess of the rates specified in
Sec. 1020.32(d)(1)(i), (d)(1)(ii), or (d)(1)(iii) at the measurement
point specified in Sec. 1020.32(d)(3), 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.
(2) Fluoroscopic equipment manufactured on or after May 19, 1995--
(i) Shall be equipped with AERC if operable at any combination of tube
potential and current that results in an AKR greater than 44 mGy per
minute (vice 5 R/min exposure rate) at the measurement point specified
in Sec. 1020.32(d)(3). Provision for manual selection of technique
factors may be provided.
(ii) Shall not be operable at any combination of tube potential and
current that will result in an AKR in excess of 88 mGy per minute (vice
10 R/min exposure rate) at the measurement point specified in Sec.
1020.32(d)(3), except as specified in Sec. 1020.32(d)(2)(iii):
(iii) Exceptions:
(A) For equipment manufactured prior to June 10, 2006, during the
recording of images from a fluoroscopic image receptor using
photographic film or a video camera when the x-ray source is operated in
a pulsed mode.
(B) For equipment manufactured on or after June 10, 2006, during the
recording of images from the fluoroscopic image receptor for the purpose
of providing 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.
(C) When a mode of operation has an optional high-level control and
the control is activated, in which case the equipment shall not be
operable at any combination of tube potential and current that will
result in an AKR in excess of 176 mGy per minute (vice 20 R/min exposure
rate) at the measurement point specified in Sec. 1020.32(d)(3). 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.
(3) Measuring compliance. Compliance with paragraph (d) of this
section shall be determined as follows:
(i) If the source is below the x-ray table, the AKR shall be
measured at 1 cm above the tabletop or cradle.
(ii) If the source is above the x-ray table, the AKR 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 type of fluoroscope, the AKR shall be measured at
30 cm from the input surface of the fluoroscopic imaging assembly, with
the source positioned at any available SID, 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.
(iv) In a C-arm type of fluoroscope having an SID less than 45 cm,
the AKR shall be measured at the minimum SSD.
(v) In a lateral type of fluoroscope, the 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 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 cm to the centerline of
the x-ray table.
(4) Exemptions. Fluoroscopic radiation therapy simulation systems
are exempt from the requirements set forth in paragraph (d) of this
section.
(e) [Reserved]
(f) Indication of potential and current. During fluoroscopy and
cinefluorography, x-ray tube potential and current shall be continuously
indicated. Deviation of x-ray tube potential and current from the
indicated values shall not exceed the maximum deviation as stated by the
manufacturer in accordance with Sec. 1020.30(h)(3).
[[Page 645]]
(g) Source-skin distance. (1) Means shall be provided to limit the
source-skin distance to not less than 38 cm on stationary fluoroscopes
and to not less than 30 cm on mobile and portable fluoroscopes. In
addition, for fluoroscopes intended for specific surgical application
that would be prohibited at the source-skin distances specified in this
paragraph, provisions may be made for operation at shorter source-skin
distances but in no case less than 20 cm. When provided, the
manufacturer must set forth precautions with respect to the optional
means of spacing, in addition to other information as required in Sec.
1020.30(h).
(2) For stationary, mobile, or portable C-arm fluoroscopic systems
manufactured on or after June 10, 2006, having a maximum source-image
receptor distance of less than 45 cm, means shall be provided to limit
the source-skin distance to not less than 19 cm. Such systems shall be
labeled for extremity use only. In addition, for those systems intended
for specific surgical application that would be prohibited at the
source-skin distances specified in this paragraph, provisions may be
made for operation at shorter source-skin distances but in no case less
than 10 cm. When provided, the manufacturer must set forth precautions
with respect to the optional means of spacing, in addition to other
information as required in Sec. 1020.30(h).
(h) Fluoroscopic irradiation time, display, and signal. (1)(i)
Fluoroscopic equipment manufactured before June 10, 2006, shall be
provided with means to preset the cumulative irradiation time of the
fluoroscopic tube. The maximum cumulative time of the timing device
shall not exceed 5 minutes without resetting. A signal audible to the
fluoroscopist shall indicate the completion of any preset cumulative
irradiation-time. Such signal shall continue to sound while x-rays are
produced until the timing device is reset. Fluoroscopic equipment may be
modified in accordance with Sec. 1020.30(q) to comply with the
requirements of Sec. 1020.32(h)(2). When the equipment is modified, it
shall bear a label indicating the statement:
Modified to comply with 21 CFR 1020.32(h)(2).
(ii) As an alternative to the requirements of this paragraph,
radiation therapy simulation systems may be provided with a means to
indicate the total cumulative exposure time during which x-rays were
produced, and which is capable of being reset between x-ray
examinations.
(2) For x-ray controls manufactured on or after June 10, 2006, there
shall be provided for each fluoroscopic tube:
(i) A display of the fluoroscopic irradiation time at the
fluoroscopist's working position. This display shall function
independently of the audible signal described in Sec.
1020.32(h)(2)(ii). The following requirements apply:
(A) When the x-ray tube is activated, the fluoroscopic irradiation
time in minutes and tenths of minutes shall be continuously displayed
and updated at least once every 6 seconds.
(B) The fluoroscopic irradiation time shall also be displayed within
6 seconds of termination of an exposure and remain displayed until
reset.
(C) Means shall be provided to reset the display to zero prior to
the beginning of a new examination or procedure.
(ii) A signal audible to the fluoroscopist shall sound for each
passage of 5 minutes of fluoroscopic irradiation time during an
examination or procedure. The signal shall sound until manually reset
or, if automatically reset, for at least 2 second.
(i) Mobile and portable fluoroscopes. In addition to the other
requirements of this section, mobile and portable fluoroscopes shall
provide an image receptor incorporating more than a simple fluorescent
screen.
(j) Display of last-image-hold (LIH). Fluoroscopic equipment
manufactured on or after June 10, 2006, shall be equipped with means to
display LIH image following termination of the fluoroscopic exposure.
(1) For an LIH image obtained by retaining pretermination
fluoroscopic images, if the number of images and method of combining
images are selectable by the user, the selection shall be indicated
prior to initiation of the fluoroscopic exposure.
(2) For an LIH image obtained by initiating a separate radiographic-
like exposure at the termination of
[[Page 646]]
fluoroscopic imaging, the techniques factors for the LIH image shall be
selectable prior to the fluoroscopic exposure, and the combination
selected shall be indicated prior to initiation of the fluoroscopic
exposure.
(3) Means shall be provided to clearly indicate to the user whether
a displayed image is the LIH radiograph or fluoroscopy. Display of the
LIH radiograph shall be replaced by the fluoroscopic image concurrently
with re-initiation of fluoroscopic exposure, unless separate displays
are provided for the LIH radiograph and fluoroscopic images.
(4) The predetermined or selectable options for producing the LIH
radiograph shall be described in the information required by Sec.
1020.30(h). The information shall include a description of any technique
factors applicable for the selected option and the impact of the
selectable options on image characteristics and the magnitude of
radiation emissions.
(k) Displays of values of AKR and cumulative air kerma. Fluoroscopic
equipment manufactured on or after June 10, 2006, shall display at the
fluoroscopist's working position the AKR and cumulative air kerma. The
following requirements apply for each x-ray tube used during an
examination or procedure:
(1) When the x-ray tube is activated and the number of images
produced per unit time is greater than six images per second, the AKR in
mGy/min shall be continuously displayed and updated at least once every
second.
(2) The cumulative air kerma in units of mGy shall be displayed
either within 5 seconds of termination of an exposure or displayed
continuously and updated at least once every 5 seconds.
(3) The display of the AKR shall be clearly distinguishable from the
display of the cumulative air kerma.
(4) The AKR and cumulative air kerma shall represent the value for
conditions of free-in-air irradiation at one of the following reference
locations specified according to the type of fluoroscope. The reference
location shall be identified and described specifically in the
information provided to users according to Sec. 1020.30(h)(6)(iii).
(i) For fluoroscopes with x-ray source below the x-ray table, x-ray
source above the table, or of lateral type, the reference locations
shall be the respective locations specified in Sec. 1020.32(d)(3)(i),
(d)(3)(ii), or (d)(3)(v) for measuring compliance with air-kerma rate
limits.
(ii) For C-arm fluoroscopes, the reference location shall be 15 cm
from the isocenter toward the x-ray source along the beam axis.
Alternatively, the reference location shall be at a point specified by
the manufacturer to represent the location of the intersection of the x-
ray beam with the patient's skin.
(5) Means shall be provided to reset to zero the display of
cumulative air kerma prior to the commencement of a new examination or
procedure.
(6) The displayed AKR and cumulative air kerma shall not deviate
from the actual values by more than 35 percent
over the range of 6 mGy/min and 100 mGy to the maximum indication of AKR
and cumulative air kerma, respectively. Compliance shall be determined
with an irradiation time greater than 3 seconds.
[70 FR 34039, June 10, 2005]