N.M. Code R. § 20.3.6.603
In addition to other requirements of this Subpart, all diagnostic x-ray systems shall meet the following requirements:
E. Beam Quality:
(1) Half-value layer:
(a) The half-value layer (HVL) of the useful beam for a given x-ray tube potential shall not be less than the values shown in Table 603.1 [Table 1 , Section 603 of 20.3.6.603 NMAC]. If it is necessary to determine such half-value layer at an x-ray tube potential which is not listed in Table 603.1 [Table I, Section 603 of 20.3.6.603 NMAC], linear interpolation or extrapolation may be made.
TABLE I
Design operating range Measured potential Half-value layer
(Kilovolts peak) (Kilovolts peak) aluminum) (Millimeters of)
Below 50 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 above HVL criteria will be considered to 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 603.2 [Table II of Section 603, 20.3.6.603 NMAC].
TABLE II
FILTRATION REQUIRED vs. OPERATING VOLTAGE
Total Filtration (inherent plus added)
Operating Voltage (millimeters aluminum
(kVp)equivalent)
Below 50 0.5 mm
50 - 70 1.5 mm
Above 70 2.5 mm
(c) Beryllium window tubes shall have a minimum of 0.5 mm aluminum equivalent filtration permanently mounted in the useful beam.
(d) For capacitor energy storage equipment, compliance shall be determined with the maximum quantity of charge per exposure.
(e) The required minimal aluminum equivalent filtration shall include the filtration contributed by all materials which are always present between the focal spot of the tube and the patient (e.g., a tabletop when the tube is mounted "under the table" and inherent filtration of the tube).
(2) Filtration control: For x-ray systems manufactured after August 1, 1974, which have variable kVPand variable filtration for the useful beam, a device shall link the kVPselector with the filter(s) and will prevent an exposure unless the minimum required amount of filtration (see Table 603.1 or Table 603.2 above [Table I or II, Section 603 of 20.3.6.603 NMAC]) is in the useful beam for the given kVPwhich has been selected.
H. Technique Indicators:
(1) The technique factors to be used during an exposure shall be indicated before the exposure begins, except when automatic exposure controls are used, in which case the technique factors which are set prior to the exposure shall be indicated.
(2) On equipment having fixed technique factors, the requirement, 603.H.1 [Paragraph (1), Subsection H., Section 603 of 20.3.6.603 NMAC], may be met by permanent markings. Indication of technique factors shall be visible from the operator's position except in the case of spot films by the fluoroscopist.
[5-3-95; 20.3.6.603 NMAC – Rn, 20 NMAC 3.1.6.603, Recompiled xx/xx/xx]