Current through Vol. 42, No. 1, September 16, 2024
(a)
Beam limitation. This Subsection applies to radiographic systems
used in the healing arts of medicine, chiropractic, and podiatry. It does not
apply to fluoroscopic, dental, veterinary, or computed tomography systems.
(1)
General purpose stationary, mobile
and portable diagnostic x-ray systems.
(A) The tube housing shall be of diagnostic
type.
(B) Adjustable collimators,
with the same degree of protection as is required of the housing, shall be
provided to restrict the useful beam to the area of clinical interest. They
shall provide for independent, stepless adjustment of at least two dimensions
of the x- ray field.
(C) A method
shall be provided for visually defining the perimeter of the x-ray field. The
total misalignment of the edges of the visually defined field with the
respective edges of the x-ray field along either the length or width of the
visually defined field shall not exceed 2 percent of the distance from the
source to the center of the visually defined field when the surface upon which
it appears is perpendicular to the axis of the x-ray beam.
(2)
Additional requirements for
stationary general purpose diagnostic x-ray systems. In addition to the
requirements of 310:281-11-14(a)(1), all stationary general purpose diagnostic
x-ray systems shall meet the following requirements:
(A) A method shall be provided to align the
center of the x-ray field with respect to the center of the image receptor to
within 2 percent of the SID.
(B)
The beam-limiting device shall indicate numerically the field size in the plane
of the image receptor to which it is adjusted.
(C) Indication of field size dimensions and
SID's shall be specified in inches and/or centimeters, and shall be such that
aperture adjustments result in x-ray field dimensions in the plane of the image
receptor which deviate from those indicated by the beam-limiting device by no
more than 2 percent of the SID when the beam axis is indicated to be
perpendicular to the plane of the image receptor.
(3)
General purpose diagnostic x-ray
systems designed for one image receptor size. Radiographic systems
designed for only one image receptor size at a fixed SID shall be provided with
means to limit the field at the plane of the image receptor to dimensions no
greater than those of the image receptor, and to align the center of the x-ray
field with the center of the image receptor to within 2 percent of the SID, or
shall be provided with means to both size and align the x- ray field such that
the x-ray field at the plane of the image receptor does not extend beyond any
edge of the image receptor.
(4)
Special purpose diagnostic x-ray systems.
(A) A means shall be provided to limit the
x-ray field in the plane of the image receptor so that such field does not
exceed each dimension of the image receptor by more than 2 percent of the SID
when the axis of the x- ray beam is perpendicular to the plane of the image
receptor.
(B) A means shall be
provided to align the center of the x-ray field with the center of the image
receptor to within 2 percent of the SID, or means shall be provided to both
size and align the x-ray field such that the x- ray field at the plane of the
image receptor does not extend beyond any edge of the image receptor.
(C) The above
310:281-11-14(a)(4)(A) and (B) may be met with a system that meets the
requirements for general purpose x-ray system as specified in
310:281-11-14(a)(1) or, when alignment means are also provided, may be met with
either:
(i) an assortment of removable,
fixed-aperture, beam-limiting devices sufficient to meet the requirement for
each combination of image receptor size and SID for which the unit is designed
with each such device having clear and permanent markings to indicate the image
receptor size and SID for which it is designed; or
(ii) a beam-limiting device having multiple
fixed apertures sufficient to meet the requirement for each combination of
image receptor size and SID for which the unit is designed. Permanent, clearly
legible markings shall indicate the image receptor size and SID for which each
aperture is designed and shall indicate which aperture is in position for use.
(b)
Radiation exposure control devices.
(1)
X-Ray control.
(A) An x-ray control shall be incorporated
into each diagnostic x-ray system such that an exposure can be terminated by
the operator at any time except:
(i) for
exposure of 0.5 second or less; or
(ii) during serial radiography when means
shall be provided to permit completion of any single exposure of the series in
process.
(B) The exposure
switch shall be of the dead-man type.
(2)
Timers. A means shall be
provided to terminate the exposure at a preset time interval, preset product of
current and time, a preset number of pulses, or a preset radiation exposure to
the image receptor. In addition, it shall not be possible to make an exposure
when the timer is set to a "zero" or "off" position.
(3)
Automatic exposure controls.
When an automatic exposure control is provided:
(A) Indication shall be made on the control
panel when this mode of operation is selected.
(B) If the x-ray tube potential is equal to
or greater than 50 kVp, the minimum exposure time for field emission equipment
rated for pulsed operation shall be equal to or less than a time interval
equivalent to two pulses.
(C) The
minimum exposure time for all systems other than that specified in
310:281-11-14(b)(3)(B) shall be equal to or less than 0.0167 second or a time
interval required to deliver 5 mAs, whichever is greater.
(D) Either the product of peak x-ray tube
potential, current, and exposure time shall be limited to not more than 60 kWs
per exposure, or the product of x-ray tube current and exposure time shall be
limited to not more than 600 mAs per exposure except that, when the x-ray tube
potential is less than 50 kVp, the product of x-ray tube current and exposure
time shall be limited to not more than 2000 mAs per exposure.
(E) A visible signal will indicate when an
exposure has been terminated at the limits required by 310:281-11-14(b)(3)(iv),
and manual resetting shall be required before further automatically timed
exposures can be made.
(4)
Reproducibility. With a
timer setting of 0.5 second or less, the average exposure period (T) shall be
greater than or equal to 5 times the maximum exposure period (T max) minus the
minimum exposure period (T min) when 4 timer tests are performed:
T
> 5(T max -
T min)
(5)
Accuracy. Deviation of measured technique factors from indicated
values of kVp and exposure time shall not exceed the limits specified for that
system by its manufacturer. In the absence of manufacturer's specifications,
the deviation shall not exceed 10 percent of the indicated value for kVp and
for times greater than 0.05 (1/20) seconds.
(c)
Source-to-Skin Distance
(SSD). All mobile or portable diagnostic x-ray systems shall be provided
with means to limit the SSD to 30 centimeters or greater.
(d)
Exposure reproducibility.
The coefficient of variation of exposure shall not exceed 0.10 when all
technique factors are held constant. This requirement is met when 4 exposures
are made at identical technique factors,and the value of the average exposure
(E) is greater than or equal to 5 times the maximum exposure (E max) minus the
minimum exposure (E min): E
>
5(E max - E min)
(e)
Linearity. The average
ratios of exposure (mR) to the indicated milliampere-seconds (mAs) product
obtained at any two consecutive tube current settings shall not differ by more
than 0.10 times their sum: [X 1 - X 2 ]
< 0.10(X 1 + X
2) where X 1 and X 2 are the average mR/mAs values obtained at each of two
consecutive tube current settings.
(f)
Radiation from capacitor energy
storage systems in standby status. Radiation emitted from the x-ray tube
when the exposure switch or timer is not activated shall not exceed a rate of 2
milliroentgens per hour at 5 centimeters from any accessible surface of the
diagnostic source assembly, with the beam-limiting device fully open.
Added at 8 Ok Reg 3503,
eff 8-15-91 (emergency); Added at 9 Ok Reg 1643, eff 5-29-92; Amended at 21 Ok
Reg 1037, eff 5-13-04
