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Monte Carlo calculation of the sensitivity of a commercial dose calibrator to gamma and beta radiation
Author(s) -
Laedermann JeanPascal,
Valley JeanFrançois,
Bulling Shelley,
Bochud François O.
Publication year - 2004
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 - 10.1118/1.1755181
Subject(s) - monte carlo method , bremsstrahlung , physics , detector , dosimetry , photon , sensitivity (control systems) , radiation , beta particle , beta (programming language) , gamma ray , nuclear physics , common emitter , computational physics , nuclear medicine , optics , optoelectronics , electronic engineering , medicine , statistics , mathematics , engineering , computer science , programming language
The detection process used in a commercial dose calibrator was modeled using the GEANT 3 Monte Carlo code. Dose calibrator efficiency for gamma and beta emitters, and the response to monoenergetic photons and electrons was calculated. The model shows that beta emitters below 2.5 MeV deposit energy indirectly in the detector through bremsstrahlung produced in the chamber wall or in the source itself. Higher energy beta emitters ( E > 2.5 MeV ) deposit energy directly in the chamber sensitive volume, and dose calibrator sensitivity increases abruptly for these radionuclides. The Monte Carlo calculations were compared with gamma and beta emitter measurements. The calculations show that the variation in dose calibrator efficiency with measuring conditions (source volume, container diameter, container wall thickness and material, position of the source within the calibrator) is relatively small and can be considered insignificant for routine measurement applications. However, dose calibrator efficiency depends strongly on the inner‐wall thickness of the detector.