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Wall‐correction and absorbed‐dose conversion factors for Fricke dosimetry: Monte Carlo calculations and measurements
Author(s) -
Ma Changming,
Rogers D. W. O.,
Shortt K. R.,
Ross C. K.,
Nahum A. E.,
Bielajew A. F.
Publication year - 1993
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 - 10.1118/1.597128
Subject(s) - dosimetry , monte carlo method , absorbed dose , percentage depth dose curve , photon , materials science , scattering , radiation , computational physics , physics , optics , nuclear medicine , ionization chamber , ionization , mathematics , medicine , ion , statistics , quantum mechanics
For megavoltage radiotherapy photon beams, EGS4 Monte Carlo calculations show, and experimental measurements confirm with an accuracy of 0.2%, that glass or quartz‐walled vials used in Fricke dosimetry increase the dose in the Fricke solution. This is mainly caused by increased electron scattering from the glass which increases the dose to the Fricke solution. The dose perturbation is shown to vary from nothing in a 60 Co beam up to 2% in a 24‐MV beam. For plastic vials of similar shapes, calculations demonstrate that the effect is in the opposite direction and even at high energies it is much less (0.2% to 0.5%).