Determination of the thermal and epithermal neutron sensitivities of an LBO chamber
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An LBO (Li2B4O7) walled ionization chamber was designed to monitor the epithermal neutron fluence in boron neutron capture therapy clinical irradiation. The thermal and epithermal neutron sensitivities of the device were evaluated using accelerator neutrons from the 9Be(d, n) reaction at a deuteron energy of 4 MeV (4 MeV d-Be neutrons). The response of the chamber in terms of the electric charge induced in the LBO chamber was compared with the thermal and epithermal neutron fluences measured using the gold-foil activation method. The thermal and epithermal neutron sensitivities obtained were expressed in units of pC cm2, i.e., from the chamber response divided by neutron fluence (cm−2). The measured LBO chamber sensitivities were 2.23 × 10−7 ± 0.34 × 10−7 (pC cm2) for thermal neutrons and 2.00 × 10−5 ± 0.12 × 10−5 (pC cm2) for epithermal neutrons. This shows that the LBO chamber is sufficiently sensitive to epithermal neutrons to be useful for epithermal neutron monitoring in BNCT irradiation.
KeywordsLBO chamber Thermal neutron sensitivity Epithermal neutron sensitivity BNCT Dose monitoring
The authors are grateful to the staff at the Biological Effects Experiments (NASBEE), National Institute for Radiological Science (NIRS) for their excellent operation of the accelerator. This study was performed as collaboration between Hiroshima University and NIRS. The authors are also grateful to Mr. Atsushi Higashimata, Sanki Industry, for manufacturing the LBO chamber. This research was supported by Japan Society for the Promotion of Science KAKENHI Grants Nos. 26257501 (April 2014–March 2018), 24310044 (April 2012–March 2015) and 15K00544 (April 2015–March 2019).
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Conflict of interest
The authors declare that there are no conflict interest.
- American Association of Physicists in Medicine by the American Institute of Physics (AAPM) (1980) Protocol for neutron beam dosimetry, AAPM report No. 7Google Scholar
- Blackburn BW, Yanch J C (1999) Liquid gallium cooling of a high-power beryllium target for use in accelerator boron neutron capture therapy (ABNCT). In: Proceedings of the 8th workshop on targetry and target chemistry, Missouri, 23–26 June 1999Google Scholar
- Bleuel DL, Donahue RJ (1996) Optimization of the 7Li(p, n) proton beam energy for BNCT application, LBL-37983. Lawrence Berkeley National Laboratory, BerkeleyGoogle Scholar
- International Commission on Radiation Units and Measurements (ICRU) (1977) Neutron dosimetry for biology and medicine-ICRU report 26. Woodmont Avenue 7910, Washington, D.C.Google Scholar
- International Commission on Radiation Units and Measurements (ICRU) (2000) Nuclear data for neutron and proton radiation therapy and radiation protection, ICRU report 63. Woodmont Avenue 7910, Washington, D.C.Google Scholar
- Suda M, Hagihara T, Suya N, Hamano T, Takada M, Konishi T, Maeda T, Ohmachi Y, Kakinuma S, Ariyoshi K, Shimada Y, Imaseki H (2009) Specifications of a neutron exposure accelerator system for biological effects experiments (NASBEE) in NIRS. Radiat Phys Chem. doi: 10.1016/j.radphyschem.2009.05.010(2009-06-03) Google Scholar