In-phantom two-dimensional thermal neutron distribution for intraoperative boron neutron capture therapy of brain tumours.
The aim of this study was to determine the in-phantom thermal neutron distribution derived from neutron beams for intraoperative boron neutron capture therapy (IOBNCT). Gold activation wires arranged in a cylindrical water phantom with (void-in-phantom) or without (standard phantom) a cylinder styrene form placed inside were irradiated by using the epithermal beam (ENB) and the mixed thermal-epithermal beam (TNB-1) at the Japan Research Reactor No 4. With ENB, we observed a flattened distribution of thermal neutron flux and a significantly enhanced thermal flux delivery at a depth compared with the results of using TNB-1. The thermal neutron distribution derived from both the ENB and TNB-1 was significantly improved in the void-in-phantom, and a double high dose area was formed lateral to the void. The flattened distribution in the circumference of the void was observed with the combination of ENB and the void-in-phantom. The measurement data suggest that the ENB may provide a clinical advantage in the form of an enhanced and flattened dose delivery to the marginal tissue of a post-operative cavity in which a residual and/or microscopically infiltrating tumour often occurs. The combination of the epithermal neutron beam and IOBNCT will improve the clinical results of BNCT for brain tumours.
Yamamoto
T
T
Department of Neurosurgery, Institute of Clinical Medicine, University of Tsukuba, Tsukuba City, Ibaraki, Japan. ttttetsu@ybb.ne.jp
Matsumura
A
A
Yamamoto
K
K
Kumada
H
H
Shibata
Y
Y
Nose
T
T
D016754:Boron Neutron Capture Therapy / Q000295:instrumentation* / Q000379:methods*; D001932:Brain Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008954:Models, Biological; D016343:Monitoring, Intraoperative / Q000379:methods*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*