Journal Article

DKFZ-2020-02466

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Helium radiography with a digital tracking calorimeter-a Monte Carlo study for secondary track rejection.

Pettersen, H. E. S. ; Volz, L.DKFZ* ; Sølie, J. R. ; Alme, J. ; Barnaföldi, G. G. ; Barthel, R. ; van den Brink, A. ; Borshchov, V. ; Chaar, M. ; Eikeland, V. N. ; Genov, G. ; Grøttvik, O. S. ; Helstrup, H. ; Keidel, R. ; Kobdaj, C. ; van der Kolk, N. ; Mehendale, S. ; Meric, I. ; Odland, O. H. ; Papp, G. ; Peitzmann, T. ; Piersimoni, P. ; Protsenko, M. ; Rehman, A. U. ; Richter, M. ; Samnøy, A. T. ; Seco, J.DKFZ* ; Shafiee, H. ; Songmoolnak, A. ; Tambave, G. ; Tymchuk, I. ; Ullaland, K. ; Varga-Kofarago, M. ; Wagner, B. ; Xiao, R. ; Yang, S. ; Yokoyama, H. ; Roehrich, D.

2021
IOP Publ. Bristol

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Please use a persistent id in citations: doi:10.1088/1361-6560/abca03

Abstract: 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.

Note: 2021 Jan 26;66(3):035004

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Contributing Institute(s):

1. E041 Medizinische Physik in der Radioonkologie (E041)

Research Program(s):

1. 315 - Bildgebung und Radioonkologie (POF4-315) (POF4-315)

Appears in the scientific report 2021

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Database coverage:
; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Life Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; National-Konsortium ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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