SECTION 310:281-11-14. Radiographic diagnostic x-ray systems

(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.

(l)   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.

(l)   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 shall 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 (Tmax) minus the minimum exposure period (Tmin) when 4 timer tests are performed:

(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 shall be deemed to have been met if, when 4 exposures are made at identical technique factors, the value of the average exposure (E) is greater than or equal to 5 times the maximum exposure (Emax) minus the minimum exposure (Emin):

(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:

where X1 and X2 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.

[Source: 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]