skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: SU-F-J-152: Accuracy of Charge Particle Transport in Magnetic Fields Using EGSnrc

Abstract

Purpose: Determine accuracy of the current implementation of electron transport under magnetic fields in EGSnrc by means of single scattering (SS) and Fano convergence tests, and establish quantitatively the electron step size restriction required to achieve a desired level of accuracy for ionization chamber dosimetry. Methods: Condensed history (CH) dose calculations are compared to SS results for a PTW30013 ionization chamber irradiated in air by a 60Co photon beam. CH dose results for this chamber irradiated in a water phantom by a source of mono-energetic electrons are compared to the prediction of Fano’s theorem for step size restrictions EM ESTEPE from 0.01 to 0.1 and strengths of 0.5 T, 1.0 T, and 1.5 T. Results: CH calculations in air for 60Co photons using an EM ESTEPE of 0.25 overestimate SS values by 6% for a 1.5 T field and by 1.5% for a 0.5 T field. Agreement improves with decreasing EM ESTEPE reducing this difference at 0.02 to 0.13% and 0.04% for 1.5 T and 0.5 T respectively. CH results converge with decreasing EM ESTEPE reaching an agreement of 0.2% at a value of EM ESTEPE of 0.01 for 100 keV electrons. SS results at 100 keV for 1.5 Tmore » show the same EM ESTEPE dependency as the CH results. Conclusion: Accurate transport of charged particles in magnetic fields is only possible if the step size is significantly restricted. An EM ESTEPE value of 0.02 is required to reproduce SS results at the 0.1% level for a calculation in air. The EM ESTEPE dependency of the SS results suggests SS is bypassed when simulating the transport of charged particles in magnetic fields. Fano test results for in water calculation suggest that only a 0.2% accuracy can be achieved with the current implementation.« less

Authors:
 [1];  [2]; ;  [3]
  1. National Research Council of Canada, Ottawa, ON (Canada)
  2. Universite de Montreal, Montreal, QC (Canada)
  3. National Research Council Canada, Ottawa, Ontario (Canada)
Publication Date:
OSTI Identifier:
22634755
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ACCURACY; CHARGED PARTICLES; COBALT 60; IONIZATION CHAMBERS; MAGNETIC FIELDS; PHANTOMS; PHOTON BEAMS; RADIATION DOSES; RADIATION TRANSPORT; TAIL ELECTRONS; WATER

Citation Formats

Mainegra-Hing, E, Bouchard, H, Tessier, F, and Walters, B. SU-F-J-152: Accuracy of Charge Particle Transport in Magnetic Fields Using EGSnrc. United States: N. p., 2016. Web. doi:10.1118/1.4956060.
Mainegra-Hing, E, Bouchard, H, Tessier, F, & Walters, B. SU-F-J-152: Accuracy of Charge Particle Transport in Magnetic Fields Using EGSnrc. United States. doi:10.1118/1.4956060.
Mainegra-Hing, E, Bouchard, H, Tessier, F, and Walters, B. Wed . "SU-F-J-152: Accuracy of Charge Particle Transport in Magnetic Fields Using EGSnrc". United States. doi:10.1118/1.4956060.
@article{osti_22634755,
title = {SU-F-J-152: Accuracy of Charge Particle Transport in Magnetic Fields Using EGSnrc},
author = {Mainegra-Hing, E and Bouchard, H and Tessier, F and Walters, B},
abstractNote = {Purpose: Determine accuracy of the current implementation of electron transport under magnetic fields in EGSnrc by means of single scattering (SS) and Fano convergence tests, and establish quantitatively the electron step size restriction required to achieve a desired level of accuracy for ionization chamber dosimetry. Methods: Condensed history (CH) dose calculations are compared to SS results for a PTW30013 ionization chamber irradiated in air by a 60Co photon beam. CH dose results for this chamber irradiated in a water phantom by a source of mono-energetic electrons are compared to the prediction of Fano’s theorem for step size restrictions EM ESTEPE from 0.01 to 0.1 and strengths of 0.5 T, 1.0 T, and 1.5 T. Results: CH calculations in air for 60Co photons using an EM ESTEPE of 0.25 overestimate SS values by 6% for a 1.5 T field and by 1.5% for a 0.5 T field. Agreement improves with decreasing EM ESTEPE reducing this difference at 0.02 to 0.13% and 0.04% for 1.5 T and 0.5 T respectively. CH results converge with decreasing EM ESTEPE reaching an agreement of 0.2% at a value of EM ESTEPE of 0.01 for 100 keV electrons. SS results at 100 keV for 1.5 T show the same EM ESTEPE dependency as the CH results. Conclusion: Accurate transport of charged particles in magnetic fields is only possible if the step size is significantly restricted. An EM ESTEPE value of 0.02 is required to reproduce SS results at the 0.1% level for a calculation in air. The EM ESTEPE dependency of the SS results suggests SS is bypassed when simulating the transport of charged particles in magnetic fields. Fano test results for in water calculation suggest that only a 0.2% accuracy can be achieved with the current implementation.},
doi = {10.1118/1.4956060},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}