Photon-beam subsource sensitivity to the initial electron-beam parameters

Fix, MK; Keall, PJ; Siebers, JV (2005). Photon-beam subsource sensitivity to the initial electron-beam parameters. Medical physics, 32(4), pp. 1164-75. College Park, Md.: American Association of Physicists in Medicine AAPM 10.1118/1.1884385

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One limitation to the widespread implementation of Monte Carlo (MC) patient dose-calculation algorithms for radiotherapy is the lack of a general and accurate source model of the accelerator radiation source. Our aim in this work is to investigate the sensitivity of the photon-beam subsource distributions in a MC source model (with target, primary collimator, and flattening filter photon subsources and an electron subsource) for 6- and 18-MV photon beams when the energy and radial distributions of initial electrons striking a linac target change. For this purpose, phase-space data (PSD) was calculated for various mean electron energies striking the target, various normally distributed electron energy spread, and various normally distributed electron radial intensity distributions. All PSD was analyzed in terms of energy, fluence, and energy fluence distributions, which were compared between the different parameter sets. The energy spread was found to have a negligible influence on the subsource distributions. The mean energy and radial intensity significantly changed the target subsource distribution shapes and intensities. For the primary collimator and flattening filter subsources, the distribution shapes of the fluence and energy fluence changed little for different mean electron energies striking the target, however, their relative intensity compared with the target subsource change, which can be accounted for by a scaling factor. This study indicates that adjustments to MC source models can likely be limited to adjusting the target subsource in conjunction with scaling the relative intensity and energy spectrum of the primary collimator, flattening filter, and electron subsources when the energy and radial distributions of the initial electron-beam change.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Haematology, Oncology, Infectious Diseases, Laboratory Medicine and Hospital Pharmacy (DOLS) > Clinic of Radiation Oncology > Medical Radiation Physics

UniBE Contributor:

Fix, Michael

ISSN:

0094-2405

ISBN:

15895600

Publisher:

American Association of Physicists in Medicine AAPM

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:56

Last Modified:

04 May 2014 23:16

Publisher DOI:

10.1118/1.1884385

PubMed ID:

15895600

Web of Science ID:

000228659700036

URI:

https://boris.unibe.ch/id/eprint/24112 (FactScience: 47004)

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