title: Analysis of Neutron Production in Passively Scattered Ion-Beam Therapy.
abstract: A new treatment facility for heavy ion therapy since 2010 was constructed. In the broad beam, a range shifter, ridge filter and multi leaf collimator (MLC) for the generation of the spread-out Bragg peak is used. In this case, secondary neutrons produced by the interactions of the ion field with beam-modifying devices (e.g. double-scattering system, beam shaping collimators and range compensators) are very important for patient safety. Therefore, these components must be carefully examined in the context of secondary neutron yield and associated secondary cancer risk. In this article, Monte Carlo simulation has been carried out with the FLUktuierende KAskade particle transport code, the fluence and distribution of neutron generation and the neutron dose equivalent from the broad beam components are compared using carbon and proton beams. As a result, it is confirmed that the yield of neutron production using a carbon beam from all components of the broad beam was higher than using a proton beam. The ambient dose by neutrons per heavy ion and proton ion from the MLC surface was 0.12-0.18 and 0.0067-0.0087 pSv, respectively, which shows that heavy ions generate more neutrons than protons. However, ambient dose per treatment 2 Gy, which means physical dose during treatment by ion beam, is higher than carbon beam because proton therapy needs more beam flux to make 2-Gy prescription dose. Therefore, the neutron production from the MLC, which is closed to the patient, is a very important parameter for patient safety.
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.|Department of Biomedical Engineering, Inje University, Gimhae, Republic of Korea.
authors.forename: Seunguk
authors.initials: S
authors.lastname: Heo
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
authors.forename: Seunghoon
authors.initials: S
authors.lastname: Yoo
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
authors.forename: Yongkeun
authors.initials: Y
authors.lastname: Song
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
authors.forename: Eunho
authors.initials: E
authors.lastname: Kim
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
authors.forename: Jaeik
authors.initials: J
authors.lastname: Shin
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
authors.forename: Soorim
authors.initials: S
authors.lastname: Han
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.
authors.forename: Wongyun
authors.initials: W
authors.lastname: Jung
authors.affiliation: Department of Biomedical Engineering, Inje University, Gimhae, Republic of Korea.
authors.forename: Sanghee
authors.initials: S
authors.lastname: Nam
authors.affiliation: Radiation Oncology, EWHA Womans University Mokdong Hospital, Seoul, Republic of Korea.
authors.forename: Rena
authors.initials: R
authors.lastname: Lee
authors.affiliation: Quantum Beam based Radiation Research Center, Korea Atomic Energy Research Institute, Daejeon, Republic of Korea.
authors.forename: Kitae
authors.initials: K
authors.lastname: Lee
authors.affiliation: Division of Heavy-ion Clinical Researches, Korea Institute of Radiological and Medical Sciences, Seoul, Republic of Korea.|Radiation Oncology, EWHA Womans University Mokdong Hospital, Seoul, Republic of Korea.
authors.forename: Sungho
authors.initials: S
authors.lastname: Cho
mesh_terms: D006801:Humans; D009010:Monte Carlo Method; D009502:Neutrons; D011522:Protons; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal
chemical_list: D011522:Protons