Out-of-field in vivo dosimetry using TLD in SABR for primary kidney cancer involving mixed photon fields

LiF:Mg,Cu,P TLD containing 6Li is sensitive enough to measure out-of-field dose 50 cm from isocentre however will over-estimate the photon component of out-of-field dose in high energy treatments due to the presence of thermal neutrons. 7Li enriched materials which are insensitive to neutrons are therefore required for accurate photon dosimetry. Neutron signal has been shown here to increase with MUs and is higher for patients treated using certain non coplanar beam arrangements. Further work is required to convert this additional neutron signal to dose.