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Study of the response of plastic scintillation detectors in small‐field 6 MV photon beams by Monte Carlo simulations
Author(s) -
Wang Lilie L. W.,
Beddar Sam
Publication year - 2011
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 - 10.1118/1.3554644
Subject(s) - monte carlo method , optics , scintillation , detector , beam (structure) , photon , core (optical fiber) , materials science , optical fiber , physics , statistics , mathematics
Purpose: To investigate the response of plastic scintillation detectors (PSDs) in a 6 MV photon beam of various field sizes using Monte Carlo simulations. Methods: Three PSDs were simulated: A BC‐400 and a BCF‐12, each attached to a plastic‐core optical fiber, and a BC‐400 attached to an air‐core optical fiber. PSD response was calculated as the detector dose per unit water dose for field sizes ranging from 10 × 10 down to 0.5 × 0.5 cm 2for both perpendicular and parallel orientations of the detectors to an incident beam. Similar calculations were performed for a CC01 compact chamber. The off‐axis dose profiles were calculated in the 0.5 × 0.5 cm 2photon beam and were compared to the dose profile calculated for the CC01 chamber and that calculated in water without any detector. The angular dependence of the PSDs' responses in a small photon beam was studied. Results: In the perpendicular orientation, the response of the BCF‐12 PSD varied by only 0.5% as the field size decreased from 10 × 10 to 0.5 × 0.5 cm 2 , while the response of BC‐400 PSD attached to a plastic‐core fiber varied by more than 3% at the smallest field size because of its longer sensitive region. In the parallel orientation, the response of both PSDs attached to a plastic‐core fiber varied by less than 0.4% for the same range of field sizes. For the PSD attached to an air‐core fiber, the response varied, at most, by 2% for both orientations. Conclusions: The responses of all the PSDs investigated in this work can have a variation of only 1%–2% irrespective of field size and orientation of the detector if the length of the sensitive region is not more than 2 mm long and the optical fiber stems are prevented from pointing directly to the incident source.