Study of the dose assessment at Proton Therapy Center, Fukui Prefectural Hospital, 2; Measurement of the neutron dose

Satoh, Daiki   ; Nakashima, Hiroshi; Shibata, Tokushi; Endo, Akira   ; Tsuda, Shuichi  ; Tameshige, Yuji*; Maeda, Yoshikazu*; Sasaki, Makoto*; Maekawa, Motokazu*; Shimizu, Yasuhiro*; Yamazaki, Masaharu*; Katayose, Tadashi*

In order to investigate the optimal design of a proton radiotherapy facility, neutron doses behind shielding walls were measured at the proton therapy center in Fukui prefectural hospital. The radiation monitors, DARWIN, WENDI-2, and REM, were used to assess the neutron doses. The doses obtained by DARWIN and WENDI-2 agreed well. It was found that the REM monitor underestimate the doses due to the lack of sensitivity to neutrons whose energy is above several tens of MeV.