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The impact of electron transport on the accuracy of computed dose
Author(s) -
Arnfield Mark R.,
Siantar Christine Hartmann,
Siebers Jeffrey,
Garmon Pamela,
Cox Larry,
Mohan Radhe
Publication year - 2000
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 - 10.1118/1.599004
Subject(s) - monte carlo method , dosimeter , computational physics , dosimetry , imaging phantom , convolution (computer science) , photon , physics , superposition principle , percentage depth dose curve , electron , stopping power , range (aeronautics) , ionization , ionization chamber , nuclear medicine , materials science , optics , radiation , mathematics , nuclear physics , computer science , statistics , ion , artificial neural network , medicine , composite material , quantum mechanics , machine learning , detector
The aim of this work was to investigate the accuracy of dose predicted by a Batho power law correction, and two models which account for electron range: A superposition/convolution algorithm and a Monte Carlo algorithm. The results of these models were compared in phantoms with cavities and low‐density inhomogeneities. An idealized geometry was considered with inhomogeneities represented by regions of air and lung equivalent material. Measurements were performed with a parallel plate ionization chamber, thin TLDs (thermoluminescent dosimeters) and film. Dose calculations were done with a generalized Batho model, the Pinnacle collapsed cone convolution model (CCC), and the Peregrine Monte Carlo dose calculation algorithm. Absolute central axis and off axis dose data at various depths relative to interfaces of inhomogeneities were compared. Our results confirm that for a Batho correction, dose errors in the calculated depth dose arise from the neglect of electron transport. This effect increases as the field size decreases, as the density of the inhomogeneity decreases, and with the energy of incident photons. The CCC calculations were closer to measurements than the Batho model, but significant discrepancies remain. Monte Carlo results agree with measurements within the measurement and computational uncertainties.