Helium radiography with a digital tracking calorimeter: a Monte Carlo study for secondary track rejection
Radiation therapy using protons and heavier ions is a fast-growing therapeutic option for cancer patients. A clinical system for particle imaging in particle therapy would enable online patient position verification, estimation of the dose deposition through range monitoring and a reduction of uncer...
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| Main Authors: | , , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
22 January 2021
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| In: |
Physics in medicine and biology
Year: 2021, Volume: 66, Issue: 3 |
| ISSN: | 1361-6560 |
| DOI: | 10.1088/1361-6560/abca03 |
| Online Access: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1088/1361-6560/abca03
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| Author Notes: | Helge Egil Seime Pettersen, Lennart Volz, Jarle Rambo Sølie, Johan Alme, Gergely Gábor Barnaföldi, Rene Barthel, Anthony van den Brink, Vyacheslav Borshchov, Mamdouh Chaar, Viljar Eikeland, Georgi Genov, Ola Grøttvik, H\aavard Helstrup, Ralf Keidel, Chinorat Kobdaj, Naomi van der Kolk, Shruti Mehendale, Ilker Meric, Odd Harald Odland, Gábor Papp, Thomas Peitzmann, Pierluigi Piersimoni, Maksym Protsenko, Attiq Ur Rehman, Matthias Richter, Andreas Tefre Samnøy, Joao Seco, Hesam Shafiee, Arnon Songmoolnak, Ganesh Tambave, Ihor Tymchuk, Kjetil Ullaland, Monika Varga-Kofarago, Boris Wagner, RenZheng Xiao, Shiming Yang, Hiroki Yokoyama and Dieter Röhrich |
| Summary: | Radiation therapy using protons and heavier ions is a fast-growing therapeutic option for cancer patients. A clinical system for particle imaging in particle therapy would enable online patient position verification, estimation of the dose deposition through range monitoring and a reduction of uncertainties in the calculation of the relative stopping power of the patient. Several prototype imaging modalities offer radiography and computed tomography using protons and heavy ions. A Digital Tracking Calorimeter (DTC), currently under development, has been proposed as one such detector. In the DTC 43 longitudinal layers of laterally stacked ALPIDE CMOS monolithic active pixel sensor chips are able to reconstruct a large number of simultaneously recorded proton tracks. In this study, we explored the capability of the DTC for helium imaging which offers favorable spatial resolution over proton imaging. Helium ions exhibit a larger cross section for inelastic nuclear interactions, increasing the number of produced secondaries in the imaged object and in the detector itself. To that end, a filtering process able to remove a large fraction of the secondaries was identified, and the track reconstruction process was adapted for helium ions. By filtering on the energy loss along the tracks, on the incoming angle and on the particle ranges, 97.5% of the secondaries were removed. After passing through 16 cm water, 50.0% of the primary helium ions survived; after the proposed filtering 42.4% of the primaries remained; finally after subsequent image reconstruction 31% of the primaries remained. Helium track reconstruction leads to more track matching errors compared to protons due to the increased available focus strength of the helium beam. In a head phantom radiograph, the Water Equivalent Path Length error envelope was 1.0 mm for helium and 1.1 mm for protons. This accuracy is expected to be sufficient for helium imaging for pre-treatment verification purposes. |
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| Item Description: | Gesehen am 09.03.2021 |
| Physical Description: | Online Resource |
| ISSN: | 1361-6560 |
| DOI: | 10.1088/1361-6560/abca03 |