Preliminary study of 3D dose distribution evaluation in neutron capture therapy using a PVA-GTA-I radiochromic gel dosimeter

Boron neutron capture therapy (BNCT) is a promising cancer treatment method that utilizes the nuclear reaction between ¹⁰B and thermal neutrons. Three-dimensional (3D) gel dosimeters are gaining attention for their potential to assess 3D dose distributions in BNCT. In this study, a PVA-GTA-I (polyvinyl alcohol crosslinked by glutaraldehyde, and iodide) radiochromic gel dosimeter, which develops a red color due to complex formation between PVA and iodide, was investigated. A PVA-GTA-I gel dosimeter, enhanced with neutron sensitizers ¹⁰B and ⁶Li, was irradiated with neutrons from a nuclear reactor. As a preliminary experiment for future evaluation of 3D dose distribution, we assessed a pseudo-one-dimensional depth dose distribution by measuring absorbance changes in a system of small gel dosimeters. The results showed that the PVA-GTA-I gel dosimeter could detect increased doses resulting from neutron capture reactions when neutron sensitizers were present. The shape of the pseudo-one-dimensional depth-dose distribution correlated well with a simple simulation. These findings suggest the potential for future 3D dose distribution measurements using large gel dosimeters and 3D optical computed tomography devices.