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Beam profiles along the nonwedged direction for large wedged fields
Author(s) -
Chui ChenShou,
LoSasso Thomas
Publication year - 1994
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 - 10.1118/1.597282
Subject(s) - beam (structure) , degree (music) , optics , penetration depth , field (mathematics) , linear particle accelerator , geometry , physics , mathematics , acoustics , pure mathematics
Beam profiles along the nonwedged direction of a wedged field produced by a linear accelerator exhibit more “sagging” than that of an open field at the same depth. For large fields, the profiles of open and wedged fields can differ by as much as 7%. The extra “sagging” of wedged profiles is mainly due to the difference in penetration between on‐ and off‐axis rays caused by the variation of beam quality across the field. An algorithm was developed to estimate an “effective” depth such that the profile of a wedged field can be approximated by the open‐field profile at the effective depth. The algorithm was verified by measured beam profiles for 6‐ and 15‐MV x‐ray beams for 15°, 30°, 45°, and 60° wedges.