New Hampshire Code of Administrative Rules
He - Department of Health and Human Services
Subtitle He-P - Former Division of Public Health Services
Chapter He-P 4000 - NEW HAMPSHIRE RULES FOR THE CONTROL OF RADIATION
Part He-P 4046 - USE OF RADIATION MACHINES: GENERAL REQUIREMENTS FOR ALL DIAGNOSTIC AND VETERINARY X-RAY SYSTEMS
Section He-P 4046.06 - Radiographic Systems Other Than Fluoroscopic, Dental Intraoral, or Computed Tomography X-ray Systems

(a) The useful beam of all radiographic systems except mammographic, fluoroscopic, dental intraoral or computed tomography systems shall be capable of being limited to the area of clinical interest.

(b) General purpose stationary and mobile x-ray systems, including veterinary systems, other than portable, shall meet the following:

(c) X-ray systems other than those described in He-P 4046.06, and all veterinary x-ray systems shall meet the following when the axis of the x-ray beam is perpendicular to the plane of the image receptor:

(d) Means shall be provided to initiate the radiation exposure only by a deliberate action on the part of the operator.

(e) An exposure shall not be possible when the timer is set to a "zero" or "off" position.

(f) Means shall be provided for visual indication observable at or from the operator's protected position whenever x-rays are produced.

(g) A signal audible to the operator shall indicate that the exposure has terminated.

(h) Means shall be provided to terminate the exposure at:

(i) Except for dental panoramic systems, termination of an exposure shall cause automatic resetting of the timer to its initial setting or to "zero."

(j) An x-ray control shall be incorporated into each x-ray system such that an exposure can be terminated manually, by the operator, at any time except for:

(k) When an automatic exposure control is provided:

(l) For systems having independent selection of exposure time settings, the average ratios (Xi) of exposure to the indicated timer setting, in units of milliroentgens per second (mR/s), obtained at any two clinically used timer settings shall not differ by more than 0.10 times their sum. This is written as:

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where X1 and X2 are the average mR/s values.

(m) The x-ray exposure control shall be so placed that the operator can view the patient while making any exposure.

(n) Stationary x-ray systems, except veterinary systems, shall be required to have the x-ray control permanently mounted in a protected area that by virtue of shielding or distance or both shall protect the operator during the entire exposure from radiation scatter and is sufficient to comply with the occupational dose limits required by He-P 4020.05.

(o) Mobile and portable x-ray systems, except veterinary systems shall meet the requirements of He-P 4046.06(n) if used continuously for greater than one week in the same location, and shall be provided with means to limit the source to skin distance equal to, or greater than 30 centimeters.

(p) All stationary, mobile or portable x-ray systems used for veterinary work shall be provided:

(q) All mobile or portable radiographic systems, except veterinary systems, shall be provided with means to limit the source-to-skin distance to equal to or greater than 30 centimeters.

(r) When all technique factors are held constant, including control panel selections associated with automatic exposure control systems, the coefficient of variation of exposure for both manual and automatic exposure control systems shall not exceed 0.05.

(s) Radiation emitted from the x-ray tube when the system is fully charged and the exposure switch or timer is not activated shall not exceed a rate of 2 milliroentgens per hour (mR/hr) at 5 centimeters from any accessible surface of the diagnostic source assembly, with the beam-limiting device fully open.

(t) Deviation of measured technique factors shall:

(u) When equipment having independent selection of x-ray tube current (mA), or a combined x-ray tube current exposure time product (mAs), is operated between 40 percent and 100 percent of the maximum rated kVp, the absolute value of the difference in the ratios (Xi) of exposure to the indicated milliampere-seconds product mR/mAs obtained at any two consecutive tube current settings shall not differ by more than 0.10 times their sum:

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where the values of X1 and X2 are the average values which are obtained at each of two consecutive tube current settings, or are obtained at two settings differing by no more than a factor of 2 where the tube current selection is continuous.