Paired miniature tissue-equivalent proportional counters for dosimetry in high flux epithermal neutron capture therapy beams

Boron neutron capture therapy (BNCT) is a promising alternative to conventional radiation therapy for highly malignant brain tumors. Due to the variety of types of radiation present, and the short range of some of these particles, accurate dosimetry for BNCT is very difficult. Low pressure tissue equivalent proportional counters (TEPCs) are able to provide detailed information about the radiation types as well as microdosimetric information by providing the complete single event spectrum of charged particles depositing the dose in a simulated microscopic site. TEPC microdosimetry for BNCT has thus far been limited by the large size of commercially available TEPCs. To overcome this problem, a pair of miniature TEPCs has been constructed with sensitive volumes of 0.0027 cm3. Design considerations for these counters as well as preliminary absorbed dose measurements are presented.