Enhancement of the EGSnrc code egs_chamber for fast fluence calculations of charged particles

Thomas Failing; Günther H. Hartmann; Frank W. Hensley; Boris Keil; Klemens Zink

Zeitschrift für Medizinische Physik (Nov 2022)

Enhancement of the EGSnrc code egs_chamber for fast fluence calculations of charged particles

Thomas Failing,
Günther H. Hartmann,
Frank W. Hensley,
Boris Keil,
Klemens Zink

Affiliations

Thomas Failing: Department for Radiotherapy and Radiooncology, University Medical Center Göttingen, Göttingen 37075, Germany; Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Gießen 35390, Germany; Corresponding author: Department for Radiotherapy and Radiooncology, University Medical Center Göttingen, Göttingen 37075, Germany.
Günther H. Hartmann: German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
Frank W. Hensley: Department for Radiotherapy and Radiooncology, University Medical Center Heidelberg, Heidelberg 69120, Germany
Boris Keil: Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Gießen 35390, Germany; Diagnostic and Interventional Radiology, Philipps-University Marburg, Marburg 35043, Germany
Klemens Zink: Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, Gießen 35390, Germany; Department for Radiotherapy and Radiooncology, University Medical Center Giessen-Marburg, Marburg 35043, Germany; Marburg Iontherapy Center (MIT), Marburg 35043, Germany

Journal volume & issue: Vol. 32, no. 4
pp. 417 – 427

Abstract

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Purpose: Simulation of absorbed dose deposition in a detector is one of the key tasks of Monte Carlo (MC) dosimetry methodology. Recent publications (Hartmann and Zink, 2018; Hartmann and Zink, 2019; Hartmann et al., 2021) have shown that knowledge of the charged particle fluence differential in energy contributing to absorbed dose is useful to provide enhanced insight on how response depends on detector properties. While some EGSnrc MC codes provide output of charged particle spectra, they are often restricted in setup options or limited in calculation efficiency. For detector simulations, a promising approach is to upgrade the EGSnrc code egs_chamber which so far does not offer charged particle calculations. Methods: Since the user code cavity offers charged particle fluence calculation, the underlying algorithm was embedded in egs_chamber. The modified code was tested against two EGSnrc applications and DOSXYZnrc which was modified accordingly by one of the authors. Furthermore, the gain in efficiency achieved by photon cross section enhancement was determined quantitatively. Results: Electron and positron fluence spectra and restricted cema calculated by egs_chamber agreed well with the compared applications thus demonstrating the feasibility of the new code. Additionally, variance reduction techniques are now applicable also for fluence calculations. Depending on the simulation setup, considerable gains in efficiency were obtained by photon cross section enhancement. Conclusion: The enhanced egs_chamber code represents a valuable tool to investigate the response of detectors with respect to absorbed dose and fluence distribution and the perturbation caused by the detector in a reasonable computation time. By using intermediate phase space scoring, egs_chamber offers parallel calculation of charged particle fluence spectra for different detector configurations in one single run.

Published in Zeitschrift für Medizinische Physik

ISSN: 0939-3889 (Print); 1876-4436 (Online)
Publisher: Elsevier
Country of publisher: Germany
LCC subjects: Medicine: Medicine (General): Medical physics. Medical radiology. Nuclear medicine
Website: https://www.sciencedirect.com/journal/zeitschrift-fur-medizinische-physik

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