Relative neutron sensitivity of tissue-equivalent ionisation chambers in an epithermal neutron beam for boron neutron capture therapy

In recent years, boron neutron capture therapy has received renewed interest as new promising boron compounds and epithermal neutron beams have become available. For establishment of the different dose components in epithermal neutron beams, various techniques are applied, including the use of tissue-equivalent (TE) ionisation chambers for the determination of the intermediate and fast neutron dose. This paper is directed towards the calculation of the relative neutron sensitivity of TE ionisation chambers, k(T), for the free-in-air spectrum at the HB11 epithermal beam facility of the High Flux Reactor in Petten. The k(T) value obtained from the present calculations is 0.87. This value is about 10% lower than data currently applied for similar conditions.