Secondary Neutron Doses for Several Beam Configurations for Proton Therapy

Journal Article · Fri May 01 00:00:00 EDT 2009 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2008.10.090· OSTI ID:21276797

Shin, Dongho; Yoon, Myonggeun; Kwak, Jungwon; Shin, Jungwook ^[1]; Park, Sung Yong ^[1]; Park, Soah ^[2]; Kim, Dae Yong; Cho, Kwan Ho ^[1]

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1. Proton Therapy Center, National Cancer Center, Goyang (Korea, Republic of)
2. Department of Radiation Oncology, Kangnam Sacred Heart Hospital, Seoul (Korea, Republic of)

Purpose: To compare possible neutron doses produced in scanning and scattering modes, with the latter assessed using a newly built passive-scattering proton beam line. Methods and Materials: A 40 x 30.5 x 30-cm water phantom was irradiated with 230-MeV proton beams using a gantry angle of 270{sup o}, a 10-cm-diameter snout, and a brass aperture with a diameter of 7 cm and a thickness of 6.5 cm. The secondary neutron doses during irradiation were measured at various points using CR-39 detectors, and these measurements were cross-checked using a neutron survey meter with a 22-cm range and a 5-cm spread-out Bragg peak. Results: The maximum doses due to secondary neutrons produced by a scattering beam-delivery system were on the order of 0.152 mSv/Gy and 1.17 mSv/Gy at 50 cm from the beam isocenter in the longitudinal (0{sup o}) and perpendicular (90{sup o}) directions, respectively. The neutron dose equivalent to the proton absorbed dose, measured from 10 cm to 100 cm from the isocenter, ranged from 0.071 mSv/Gy to 1.96 mSv/Gy in the direction of the beam line (i.e., {phi} = 0 deg.). The largest neutron dose, of 3.88 mSv/Gy, was observed at 135{sup o} and 25 cm from the isocenter. Conclusions: Although the secondary neutron doses in proton therapy were higher when a scattering mode rather than a scanning mode was used, they did not exceed the scattered photon dose in typical photon treatments.

• OSTI ID: 21276797
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Vol. 74, Issue 1; Other Information: DOI: 10.1016/j.ijrobp.2008.10.090; PII: S0360-3016(09)00095-9; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BRAGG CURVE
MEV RANGE 100-1000
NEUTRONS
PHANTOMS
PHOTONS
PROTON BEAMS
PROTONS
RADIATION DOSES
RADIOTHERAPY
SCATTERING