New concept for neutron dosimetry in ion beam radiotherapy: Feasibility study

• Published in: Radiation physics and chemistry (Oxford, England : 1993) Vol. 223; p. 112014
• Main Authors: Aoki, Katsumi, Yonai, Shunsuke
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2024
• Subjects: Carbon-ion radiotherapy; Hydrogen-filled proportional counter; Neutron dosimetry; Neutron energy spectrum; Secondary neutron; Neutron energy spectrum; Carbon-ion radiotherapy; Secondary neutron; Neutron dosimetry; Hydrogen-filled proportional counter
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/j.radphyschem.2024.112014

In ion beam radiotherapy (IBRT), the secondary neutrons contribute to whole-body exposure, potentially increasing the risk of radiation-induced cancer. The energy range of neutrons generated in the IBRT treatment room spreads from thermal to a few hundred MeV, with those between 0.1 and a few hundred MeV playing a crucial role in the ambient dose equivalent. This study introduces a novel approach for measuring the ambient dose equivalent that focuses on the neutron energy spectrum in the IBRT treatment room. Distinguished by the use of a hydrogen-filled proportional counter and a single moderator, this new method overcomes the weakness of the traditional Bonner Sphere Spectrometer by reducing the complexity and time required for measurements. By deriving the neutron energy spectrum, the neutron ambient dose equivalent can be accurately calculated. Our validation demonstrated that the neutron ambient dose equivalents derived using our method closely agree with the actual values, with discrepancies within 4%, underscoring the feasibility of this innovative approach to neutron dosimetry in the IBRT treatment room. •A new concept for the experimental determination of neutron H*(10) is proposed.•The H*(10) is determined based on the energy spectrum through a single measurement.•This method overcomes the weakness of the conventional measurement method.•Our validation showed that this method reproduces the actual values well.•These findings affirm the practicality of the method in the IBRT treatment room.