A γ-ray telescope for on-line measurements of low boron concentrations in a head phantom for BNCT

In Boron neutron capture therapy the 10B(n,α)7Li reaction is used to create a tumour-destructing field of high linear energy transfer (LET) particles. The therapy requires a high boron concentration in the tumour and a low boron concentration in the healthy tissue. The boron neutron capture reaction is accompanied by the emission of a photon of energy 478 keV. It is investigated whether measuring of these photons can serve as a tool to determine the boron concentration during therapy in the tumour as well as in the healthy tissue. Such a measurement is complicated by the presence of a large background photon field. To study the feasibility, an experimental configuration has been designed at a test facility of the low-flux reactor (LFR). The LFR provides an epithermal neutron beam for irradiation of a head phantom which simulates a human head with a tumour. This paper shows that the reconstruction of the position and the size of the tumour as well as the ratio of the boron concentrations appeared to be possible. In a second stage it is shown that these measurements can be expanded to experiments with the therapy neutron beam of the high-flux reactor (HFR). (orig.)