Pennsylvania Code
Title 25 - ENVIRONMENTAL PROTECTION
Part I - Department of Environmental Protection
Subpart D - Environmental Health and Safety
Article V - Radiological Health
Chapter 228 - RADIATION SAFETY REQUIREMENTS FOR PARTICLE ACCELERATORS
RADIATION SAFETY REQUIREMENTS FOR ACCELERATORS USED IN THE HEALING ARTS
Section 228.65 - Electron beam quality
Universal Citation: 25 PA Code ยง 228.65
Current through Register Vol. 54, No. 44, November 2, 2024
The licensee shall determine that the following beam quality requirements are met:
(1) The absorbed dose resulting from X-rays in a useful electron beam at a point on the central axis of the beam 10 centimeters greater than the practical range of the electrons may not exceed the values in Table I. Linear interpolation shall be used for values not stated.
Table I
| Maximum Energy of Electron Beam in MeV | X-Ray Absorbed Dose as a Fraction of Maximum Absorbed Dose |
| 1 | 0.03 |
| 15 | 0.05 |
| 35 | 0.10 |
| 50 | 0.20 |
(2) Compliance with paragraph (1) shall be determined using:
(i) A measurement within a
phantom with the incident surface of the phantom at the normal treatment
distance and normal to the central axis of the beam.
(ii) The largest field size available which
does not exceed 15 centimeters by 15 centimeters.
(iii) A phantom whose cross-sectional
dimensions exceed the measurement radiation field by at least 5 centimeters and
whose depth is sufficient to perform the required measurement.
(3) The licensee shall determine, or obtain from the manufacturer, the maximum percentage absorbed dose due to stray neutrons in the useful beam for specified operating conditions.
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