Okla. Admin. Code § 252:410-11-54

Current through Vol. 41, No. 19, June 17, 2024

Section 252:410-11-54 - Beam quality

For systems of 1 MeV or more, the permittee must determine, or obtain from the manufacturer, data sufficient to assure that the following beam energy 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 shall not exceed the values stated in Appendix D. Linear interpolation shall be used for values not stated. Compliance with this subsection shall be determined using:

(A) 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;

(B) the largest field size available which does not exceed 15 by 15 centimeters; and

(C) 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.

(2) The absorbed dose at a surface located at the normal treatment distance, at the point of intersection of that surface with the central axis of the useful beam during x-ray irradiation, shall not exceed the limits stated in the Appendix E. Linear interpolation shall be used for values not stated. Compliance with this subsection shall be determined by measurements made:

(A) within a phantom using an instrument which will allow extrapolation to the surface absorbed dose;

(B) using a phantom whose size and placement meet the requirements of paragraphs (1)(A) and (C) of this section;

(C) after removal of all beam modifying devices which can be removed without the use of tools, except for beam scattering or beam flattening filters; and

(D) using the largest field size available which does not exceed 15 by 15 centimeters.

(3) The permittee shall determine, or obtain from the manufacturer, the maximum percentage absorbed dose in the useful beam due to neutrons, excluding stray neutron radiation, for specified operating conditions.

Okla. Admin. Code § 252:410-11-54

Added at 17 Ok Reg 1136, eff 6-1-00