In-phantom dosimetry using CaF2: Tm (TLD-300) ribbons

Abstract

Parameters of calibrating CaF₂ : Tm for in-phantom dosimetry of therapeutically used fast neutron and ⁶⁰Co γ-ray beams have been studied. For ⁶⁰Co γ-ray beams the over-response, outside the main beam and at depths in phantom for large fields of irradiations is significant, and is higher for its 240°C glow peak than for its 150°C peak. The difference in the photon energy dependences of the two peaks of CaF₂ : Tm (Z_eff = 16.3), which is responsible for the above effect, is discussed. For therapeutically used cyclotron-produced fast neutron beams, the γ-ray absorbed dose component from photons of energy less than 200 keV is negligible.