Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy

This study aimed to investigate the distribution of thermal neutron fluence generated during proton-beam therapy (PBT) scanning, focusing on neutrons produced within the body using Monte Carlo simulations (MCSs). MCSs used the Particle and Heavy Ion Treatment Code System to define a 35 × 35 × 35 cm&...

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Main Authors: Takahiro Shimo, Shintaro Shiba, Hiroyuki Watanabe, Masashi Yamanaka, Kazuki Matsumoto, Akihiro Yamano, Hisato Nagano, Kohichi Tokuuye
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/15/12/6833
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author Takahiro Shimo
Shintaro Shiba
Hiroyuki Watanabe
Masashi Yamanaka
Kazuki Matsumoto
Akihiro Yamano
Hisato Nagano
Kohichi Tokuuye
author_facet Takahiro Shimo
Shintaro Shiba
Hiroyuki Watanabe
Masashi Yamanaka
Kazuki Matsumoto
Akihiro Yamano
Hisato Nagano
Kohichi Tokuuye
author_sort Takahiro Shimo
collection DOAJ
description This study aimed to investigate the distribution of thermal neutron fluence generated during proton-beam therapy (PBT) scanning, focusing on neutrons produced within the body using Monte Carlo simulations (MCSs). MCSs used the Particle and Heavy Ion Treatment Code System to define a 35 × 35 × 35 cm<sup>3</sup> water phantom, and proton-beam energies ranging from 70.2 to 228.7 MeV were investigated. The MCS results were compared with neutron fluence measurements obtained from gold activation analysis, showing good agreement with a difference of 3.54%. The internal thermal neutron distribution generated by PBT was isotropic around the proton-beam axis, with the Bragg peak depth varying between 3.45 and 31.9 cm, while the thermal neutron peak depth ranged from 5.41 to 15.9 cm. Thermal neutron generation depended on proton-beam energy, irradiated particle count, and depth. Particularly, the peak of the thermal neutron fluence did not occur within the treatment target volume but in a location outside the target, closer to the source. This discrepancy between the Bragg peak and the thermal neutron fluence peak is a key finding of this study. These data are crucial for optimizing beam angles to maximize dose enhancement within the target during clinical applications of neutron capture-enhanced particle therapy.
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spelling doaj-art-eeb2ed74142e46a18b85a714c8880e172025-08-20T02:24:31ZengMDPI AGApplied Sciences2076-34172025-06-011512683310.3390/app15126833Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton TherapyTakahiro Shimo0Shintaro Shiba1Hiroyuki Watanabe2Masashi Yamanaka3Kazuki Matsumoto4Akihiro Yamano5Hisato Nagano6Kohichi Tokuuye7Department of Radiological Science, Graduate School of Health Sciences, Showa Medical University, 1-5-8 Hatanodai, Shinagawa-ku, Toyko 142-8555, JapanDepartment of Radiation Oncology, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura City 247-8533, JapanDepartment of Radiological Science, Graduate School of Health Sciences, Showa Medical University, 1-5-8 Hatanodai, Shinagawa-ku, Toyko 142-8555, JapanDepartment of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura City 247-8533, JapanDepartment of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura City 247-8533, JapanDepartment of Medical Physics, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura City 247-8533, JapanDepartment of Radiation Oncology, Shonan Fujisawa Tokushukai Hospital, 1-5-1 Kandai Tsujido, Fijisawa City 251-0041, JapanDepartment of Radiation Oncology, Shonan Kamakura General Hospital, 1370-1 Okamoto, Kamakura City 247-8533, JapanThis study aimed to investigate the distribution of thermal neutron fluence generated during proton-beam therapy (PBT) scanning, focusing on neutrons produced within the body using Monte Carlo simulations (MCSs). MCSs used the Particle and Heavy Ion Treatment Code System to define a 35 × 35 × 35 cm<sup>3</sup> water phantom, and proton-beam energies ranging from 70.2 to 228.7 MeV were investigated. The MCS results were compared with neutron fluence measurements obtained from gold activation analysis, showing good agreement with a difference of 3.54%. The internal thermal neutron distribution generated by PBT was isotropic around the proton-beam axis, with the Bragg peak depth varying between 3.45 and 31.9 cm, while the thermal neutron peak depth ranged from 5.41 to 15.9 cm. Thermal neutron generation depended on proton-beam energy, irradiated particle count, and depth. Particularly, the peak of the thermal neutron fluence did not occur within the treatment target volume but in a location outside the target, closer to the source. This discrepancy between the Bragg peak and the thermal neutron fluence peak is a key finding of this study. These data are crucial for optimizing beam angles to maximize dose enhancement within the target during clinical applications of neutron capture-enhanced particle therapy.https://www.mdpi.com/2076-3417/15/12/6833proton-beam therapyneutron capture-enhanced particle therapyMonte Carlo simulation
spellingShingle Takahiro Shimo
Shintaro Shiba
Hiroyuki Watanabe
Masashi Yamanaka
Kazuki Matsumoto
Akihiro Yamano
Hisato Nagano
Kohichi Tokuuye
Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy
Applied Sciences
proton-beam therapy
neutron capture-enhanced particle therapy
Monte Carlo simulation
title Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy
title_full Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy
title_fullStr Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy
title_full_unstemmed Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy
title_short Investigating the Secondary Thermal Neutron Intensity of Neutron Capture-Enhanced Proton Therapy
title_sort investigating the secondary thermal neutron intensity of neutron capture enhanced proton therapy
topic proton-beam therapy
neutron capture-enhanced particle therapy
Monte Carlo simulation
url https://www.mdpi.com/2076-3417/15/12/6833
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