Evaluation of thermal neutron irradiation field using a cyclotron-based neutron source for alpha autoradiography

•We developed a thermal neutron irradiation field using cyclotron based epithermal neutron source combination with a water phantom for alpha autoradiography.•The uniform thermal neutron irradiation field with an intensity of 1.7×109 (cm−2 s−1) with a size of 40 mm in diameter was obtained.•Demonstration test of alpha autoradiography using a liver sample with the injection of BPA was performed.•Boron image discriminated with the background event of protons was clearly shown by means of the particle identification.

It is important to measure the microdistribution of 10B in a cell to predict the cell-killing effect of new boron compounds in the field of boron neutron capture therapy. Alpha autoradiography has generally been used to detect the microdistribution of 10B in a cell. Although it has been performed using a reactor-based neutron source, the realization of an accelerator-based thermal neutron irradiation field is anticipated because of its easy installation at any location and stable operation. Therefore, we propose a method using a cyclotron-based epithermal neutron source in combination with a water phantom to produce a thermal neutron irradiation field for alpha autoradiography. This system can supply a uniform thermal neutron field with an intensity of 1.7×109 (cm−2 s−1) and an area of 40 mm in diameter. In this paper, we give an overview of our proposed system and describe a demonstration test using a mouse liver sample injected with 500 mg/kg of boronophenyl-alanine.