§ 221.25. Beam quality.

 (a)  Diagnostic X-ray systems shall have filtration that satisfies the requirements of Table I. The requirements of this section shall be considered to have been met if it can be demonstrated that the half value layer of the primary beam is not less than that shown in Table II.

TABLE I


Filtration Required vs. Operating Voltage

Operating Voltage (kVp) Total Filtration (inherent plus added)
(millimeters aluminum equivalent)
Below 50 0.5 millimeters
50—70 1.5 millimeters
Above 70 2.5 millimeters


TABLE II


X-Ray Tube Voltage (kilovolt peak)



Design Operating Range Measured Operating Potential Minimum HVL (mm of Aluminum)
Specified Dental
Systems1
Other X-Ray
Systems2
Other X-Ray
Systems3
Below 51 30 1.5 0.3 0.3
40 1.5 0.4 0.4
50 1.5 0.5 0.5
51 to 70 51 1.5 1.2 1.3
60 1.5 1.3 1.5
70 1.5 1.5 1.8
Above 70 71 2.1 2.1 2.5
80 2.3 2.3 2.9
90 2.5 2.5 3.2
100 2.7 2.7 3.6
110 3.0 3.0 3.9
120 3.2 3.2 4.3
130 3.5 3.5 4.7
140 3.8 3.8 5.0
150 4.1 4.1 5.4

 1 Dental X-ray systems designed for use with intraoral image receptors and manufactured after December 1, 1980.

 2 Dental X-ray systems designed for use with intraoral image receptors and manufactured before or on December 1, 1980, and all other X-ray systems subject to this section and manufactured before June 10, 2006.

 3 All X-ray systems, except dental X-ray systems designed for use with intraoral image receptors, subject to this section and manufactured on or after June 10, 2006.

 Note: Half-value layers for kilovoltages not listed in Table II may be determined by interpolation or extrapolation.

 (b)  Beryllium window tubes shall have a minimum of 0.5 millimeter aluminum equivalent filtration permanently installed in the useful beam.

 (c)  For capacitor energy storage equipment, compliance with this section shall be determined with the maximum quantity of charge per exposure.

 (d)  The required minimal aluminum equivalent filtration shall include the filtration contributed by materials which are always present between the source and the patient.

 (e)  For X-ray systems having variable filtration in the useful beam, a means shall be provided to prohibit exposure unless the filtration requirements of subsection (a) are met for the kVp selected.

Authority

   The provisions of this §  221.25 issued and amended under sections 301 and 302 of the Radiation Protection Act (35 P.S. § §  7110.301 and 7110.302); and section 1920-A of The Administrative Code of 1929 (71 P.S. §  510-20).

Source

   The provisions of this §  221.25 adopted December 18, 1987, effective December 19, 1987, 17 Pa.B. 5235; amended July 16, 2004, effective July 17, 2004, 34 Pa.B. 3238; amended October 26, 2018, effective January 24, 2019, 48 Pa.B. 6791. Immediately preceding text appears at serial pages (304494) to (304496).

Cross References

   This section cited in 25 Pa. Code §  221.35a (relating to fluoroscopic X-ray systems).



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