Experimental feasibility study of proton therapy range verification by a digital tracking calorimeter prototype

Abstract Objective. Uncertainties in the proton range remain an important challenge in proton therapy. In-situ range verification techniques can be used to ensure the Bragg peak depth in the patient matches the treatment plan. Various such methods are under investigation, utilizing the signal from secondary radiation caused by proton interactions with the patient. This study experimentally investigates the feasibility of using a silicon-pixel-based sampling calorimeter for range verification through the detection of secondary photons and neutrons. Approach. The proton range verification capability of a sampling calorimeter based on monolithic active pixel sensors was tested both theoretically and experimentally. We theoretically investigate the plausibility of the planned sampling calorimeter to pick up a signal from the neutral secondary particles distal to the patient. Then, a smaller prototype pixel telescope was constructed to verify our theoretical findings experimentally by placing it behind a water tank irradiated by a medical proton beam with various energies in the range of 100–200 MeV at the Danish Centre for Particle Therapy, Aarhus, Denmark. Main results. We find that the aluminum used as absorbers between sensitive layers in the calorimeter serves as a converter for prompt gammas and neutrons. The combined detection efficiency ranges between 5.8·10 -5 and 2.7·10 -3 detector hits per primary proton for beam energies between 50 and 200 MeV. Irradiation of the water phantom leads to a signal in our detector, which is well-correlated with the nominal beam energy. A simulation-based model using only the number of hits per proton can predict the beam energy, acting as a proxy for proton range in a homogeneous target, down to a root mean squared error of 1.34 MeV. Significance. This study marks a promising step towards utilizing a tracking calorimeter designed for proton computed tomography for the secondary application of proton therapy range verification without additional hardware costs.

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Publication Details

Journal
Physics in Medicine and Biology
Published
2026-10-29
DOI
https://doi.org/10.1088/1361-6560/aebb8a
Primary Topic
Radiation Therapy and Dosimetry
Type
article
Field-Weighted Citation Impact
0.00

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Experimental feasibility study of proton therapy range verification by a digital tracking calorimeter prototype

O.H. Odland, T. Bodova, Jacob Johansen, Helge Egil Seime Pettersen et al.
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Physics in Medicine and Biology
Radiation Therapy and Dosimetry
article

Experimental feasibility study of proton therapy range verification by a digital tracking calorimeter prototype

O.H. Odland, T. Bodova, Jacob Johansen, Helge Egil Seime Pettersen, Ihor Tymchuk, V. Borshchov, Nicolas R. Gauger, N. Ritjoho, Alexander B. Schilling, CHINORAT KOBDAJ, R. Keidel, Natthawut Laojamnongwong, Hira Sharif, Tobias Kortus, Maksym Protsenko, Michael Richter, G. Bíró, L. Charoonratana, Gábor Papp, S. N. Igolkin, A. van den Brink, J. Yi, J. Alme, G. G. Barnaföldi, Tawanchat Simantathammakul, Zs. Jólesz, Thomas Peitzmann, Attiq Ur Rehman, Kjetil Ullaland, Illia Borshchov, Thitayawat Khumwong, Dieter Röhrich, Shiming Yang, Grigori Feofilov, Håvard Helstrup, Bence Dudás
article en

Abstract

Abstract Objective. Uncertainties in the proton range remain an important challenge in proton therapy. In-situ range verification techniques can be used to ensure the Bragg peak depth in the patient matches the treatment plan. Various such methods are under investigation, utilizing the signal from secondary radiation caused by proton interactions with the patient. This study experimentally investigates the feasibility of using a silicon-pixel-based sampling calorimeter for range verification through the detection of secondary photons and neutrons. Approach. The proton range verification capability of a sampling calorimeter based on monolithic active pixel sensors was tested both theoretically and experimentally. We theoretically investigate the plausibility of the planned sampling calorimeter to pick up a signal from the neutral secondary particles distal to the patient. Then, a smaller prototype pixel telescope was constructed to verify our theoretical findings experimentally by placing it behind a water tank irradiated by a medical proton beam with various energies in the range of 100–200 MeV at the Danish Centre for Particle Therapy, Aarhus, Denmark. Main results. We find that the aluminum used as absorbers between sensitive layers in the calorimeter serves as a converter for prompt gammas and neutrons. The combined detection efficiency ranges between 5.8·10 -5 and 2.7·10 -3 detector hits per primary proton for beam energies between 50 and 200 MeV. Irradiation of the water phantom leads to a signal in our detector, which is well-correlated with the nominal beam energy. A simulation-based model using only the number of hits per proton can predict the beam energy, acting as a proxy for proton range in a homogeneous target, down to a root mean squared error of 1.34 MeV. Significance. This study marks a promising step towards utilizing a tracking calorimeter designed for proton computed tomography for the secondary application of proton therapy range verification without additional hardware costs.

Physics in Medicine and Biology
Eötvös Loránd University (HU), St Petersburg University (RU), Western Norway University of Applied Sciences (NO), Utrecht University (NL), Haukeland University Hospital (NO), Aarhus University Hospital (DK), Central China Normal University (CN), HUN-REN Wigner Research Centre for Physics (HU), Rheinland-Pfälzische Technische Universität Kaiserslautern-Landau (DE), University of Bergen (NO), Suranaree University of Technology (TH), University of Jyväskylä (FI)
CERN, Norges Forskningsråd
Openalex Percentile: Top 12%
Radiation Therapy and Dosimetry
DOIOpen Access PDFOpenAlex
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