McManus, Michael;
Romano, Francesco;
Royle, Gary J;
Botnariuc, Daniela;
Shipley, David R;
Palmans, Hugo;
Subiel, Anna;
(2022)
Determination of beam quality correction factors for the Roos plane-parallel ionisation chamber exposed to very high energy electron (VHEE) beams using Geant4.
Physics in Medicine & Biology
10.1088/1361-6560/ac5a94.
(In press).
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Abstract
Detailed characterisation of the Roos secondary standard plane-parallel ionisation chamber has been conducted in a novel 200 MeV Very High Energy Electron (VHEE) beam with reference to the standard 12 MeV electron calibration beam used in our experimental work. Stopping-power-ratios and perturbation factors have been determined for both beams and used to calculated the beam quality correction factor using the Geant4 general purpose MC code. These factors have been calculated for a variety of charged particle transport parameters available in Geant4 which were found to pass the Fano cavity test. Stopping-power-ratios for the 12 MeV electron calibration beam quality were found to agree within uncertainties to that quoted by current dosimetry protocols. Perturbation factors were found to vary by up-to 4% for the calibration beam depending on the parameter configuration, compared with only 0.8% for the VHEE beam. Beam quality correction factors were found to describe an approximately 10% lower dose than would be originally calculated if a beam quality correction were not accounted for. Moreover, results presented here largely resolve unphysical chamber measurements, such as collection efficiencies greater than 100%, and assist in the accurate determination of absorbed dose and ion recombination in secondary standard ionisation chambers.
| Type: | Article |
|---|---|
| Title: | Determination of beam quality correction factors for the Roos plane-parallel ionisation chamber exposed to very high energy electron (VHEE) beams using Geant4 |
| Location: | England |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1088/1361-6560/ac5a94 |
| Publisher version: | http://dx.doi.org/10.1088/1361-6560/ac5a94 |
| Language: | English |
| Additional information: | Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Although reasonable endeavours have been taken to obtain all necessary permissions from third parties to include their copyrighted content within this article, their full citation and copyright line may not be present in this Accepted Manuscript version. Before using any content from this article, please refer to the Version of Record on IOPscience once published for full citation and copyright details, as permission may be required. All third party content is fully copyright protected, and is not published on a gold open access basis under a CC BY licence, unless that is specifically stated in the figure caption in the Version of Record. |
| Keywords: | Monte Carlo, VHEE, beam quality correction, geant4, perturbation factors |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Med Phys and Biomedical Eng UCL > Provost and Vice Provost Offices > UCL BEAMS UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10144939 |
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