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A generic off‐axis energy correction for linac photon beam dosimetry
Author(s) -
Tailor R. C.,
Tello V. M.,
Schroy C. B.,
Vossler M.,
Hanson W. F.
Publication year - 1998
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598249
Subject(s) - linear particle accelerator , dosimetry , physics , beam (structure) , photon , optics , photon energy , energy (signal processing) , particle accelerator , medical physics , computational physics , nuclear medicine , medicine , quantum mechanics
Cooperative clinical trial group protocols frequently require off‐axis point dose calculations. The Radiological Physics Center uses the calculative technique developed by Hanson et al. [Med. Phys. 7 , 145–146 (1980); 7 , 147–150 (1980)] to verify these calculations. In order to correct for off‐axis energy changes, this technique requires off‐axis half‐value layer data, HVL, as a function of off‐axis ray angle for the specific beam. This paper presents a formulism based on HVL measurements on a limited number of therapy beams, which allows the calculation of an off‐axis energy‐correction factor for any clinical photon beam created by a linear accelerator using conventional flattening filters.