NAC459.564. Diagnostic X-ray systems.

In addition to other requirements of NAC 459.400 to 459.624, inclusive, all diagnostic X-ray systems must meet the following requirements:

     1. The control panel containing the main power switch must bear the warning statement, legible and accessible to view: “WARNING: This X-ray unit may be dangerous to patient and operator unless safe exposure factors and operating instructions are observed.”

     2. On battery-powered generators, visual means must be provided on the control panel to indicate whether the battery is in a state of charge adequate for proper operation.

     3. The leakage radiation from the diagnostic source assembly measured at a distance of 1 meter in any direction from the source must not exceed 100 milliroentgens in 1 hour when the X-ray tube is operated at its leakage technique factors. Compliance will be determined by measurements averaged over an area of 100 square centimeters with no linear dimension greater than 20 centimeters.

     4. The radiation emitted by a component other than the diagnostic source assembly must not exceed 2 milliroentgens in 1 hour at 5 centimeters from any accessible surface of the component when it is operated in an assembled X-ray system under any conditions for which it was designed. Compliance will be determined by measurements averaged over an area of 100 square centimeters with no linear dimension greater than 20 centimeters.

     5. The requisites for quality of the beam are:

     (a) The half-value layer of the useful beam for a given X-ray tube potential must not be less than the values shown in Table I. If it is necessary to determine the half-value layer at X-ray tube potential which is not listed in Table I, linear interpolation or extrapolation may be made.

TABLE I
Design operating range (Kilovolts peak)	Measured potential (Kilovolts peak)	Half-value layer (Milli- meters of aluminum)
Below................................................... 30		0.3
	40	0.4
	49	0.5
50 to 70................................................ 50		1.2
	60	1.3
	70	1.5
Above 70.............................................. 71		2.1
	80	2.3
	90	2.5
	100	2.7
	110	3.0
	120	3.2
	130	3.5
	140	3.8
	150	4.1

     (b) The half-value layer criteria will have been met if it can be demonstrated that the aluminum equivalent of the total filtration in the primary beam is not less than that shown in Table II.

TABLE II
Filtration Required vs. Operating Voltage
	Total Filtration
	(inherent plus added)
Operating Voltage (kVp)	(millimeters aluminum
	equivalent)
Below 50.................................................................................	0.5 millimeters
50-70.......................................................................................	1.5 millimeters
Above 70.................................................................................	2.5 millimeters

     (c) Beryllium window tubes must have a minimum of 0.5 mm aluminum equivalent filtration permanently mounted in the useful beam.

     (d) For capacitor energy storage equipment, compliance will be determined with the maximum quantity of charge per exposure.

     (e) The required minimal aluminum equivalent filtration must include the filtration contributed by all materials which are always present between the focal spot of the tube and the patient, for example, a tabletop when the tube is mounted under the table and inherent filtration of the tube.

     6. Where two or more radiographic tubes are controlled by one exposure switch, the tube or tubes which have been selected must be clearly indicated before initiation of the exposure. This indication must be on the X-ray control.

     7. The tube housing assembly supports must be adjusted so that the tube housing assembly will remain stable during an exposure unless the tube housing movement is a designed function of the X-ray system.

     8. The technique factors to be used during an exposure must be indicated before the exposure begins. If automatic exposure controls are used, the technique factors which are set before the exposure must be indicated. On equipment having fixed technique factors, this requirement may be met by permanent markings. Indication of technique factors must be visible from the operator’s position except in the case of spot films made by the fluoroscopist.

     [Bd. of Health, Radiation Control Reg. §§ 6.4-6.4.8.2, eff. 2-28-80]—(NAC A 4-27-84)