TLD 300 Dosimetry in a 175 MeV Proton Beam

TLD-300 dosemeters have been successfully employed in high LET radiotherapeutic fields generated by fast neutron, negative pion and heavy ion beams. By proper peak height analysis of the two main peaks of CaF2:Tm glow curves after such irradiations it is possible to separate the high and low LET content of the radiation field. Therefore the distribution of the biological equivalent dose can be determined in a single irradiation. The method was extended to a pre-therapeutic proton field of 175 MeV maximum kinetic energy. It turned out that in such proton fields the sensitivity of the high temperature peak is constant; thus the dose can be determined to an accuracy of ±4%. The sensitivity of the low temperature peak decreases linearly to 50% as a function of yD such that the average lineal energy can be determined to an accuracy of ±5 keV.μm-1. (author)