Pennsylvania Code
Title 25 - ENVIRONMENTAL PROTECTION
Part I - Department of Environmental Protection
Subpart D - Environmental Health and Safety
Article V - Radiological Health
Chapter 221 - X-RAYS IN THE HEALING ARTS
DIAGNOSTIC INSTALLATIONS GENERAL REQUIREMENTS
Section 221.25 - Beam quality
Current through Register Vol. 54, No. 44, November 2, 2024
(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.
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).
This section cited in 25 Pa. Code § 221.35a (relating to fluoroscopic X-ray systems).
