Open AccessNeutron source strength measurements for Varian, Siemens, Elekta, and General Electric linear accelerators
Author(s) -
Followill David S.,
Stovall Marilyn S.,
Kry Stephen F.,
Ibbott Geoffrey S.
Publication year - 2003
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1120/jacmp.v4i3.2514
Subject(s) - siemens , linear particle accelerator , neutron source , neutron , nuclear physics , physics , thermoluminescent dosimeter , nuclear medicine , nuclear engineering , medical physics , optics , medicine , radiation , dosimeter , beam (structure) , engineering , quantum mechanics
The shielding calculations for high energy ( > 10 MV ) linear accelerators must include the photoneutron production within the head of the accelerator. Procedures have been described to calculate the treatment room door shielding based on the neutron source strength ( Q value) for a specific accelerator and energy combination. Unfortunately, there is currently little data in the literature stating the neutron source strengths for the most widely used linear accelerators. In this study, the neutron fluence for 36 linear accelerators, including models from Varian, Siemens, Elekta/Philips, and General Electric, was measured using gold‐foil activation. Several of the models and energy combinations had multiple measurements. The neutron fluence measured in the patient plane was independent of the surface area of the room, suggesting that neutron fluence is more dependent on the direct neutron fluence from the head of the accelerator than from room scatter. Neutron source strength, Q , was determined from the measured neutron fluences. As expected, Q increased with increasing photon energy. The Q values ranged from 0.02 for a 10 MV beam to 1.44 ( × 10 12 ) neutrons per photon Gy for a 25 MV beam. The most comprehensive set of neutron source strength values, Q , for the current accelerators in clinical use are presented for use in calculating room shielding. PACS number(s): 87.53.–j, 87.52.–g