THE RESPONSE BEHAVIOR OF LIF-MG, CU, P THERMOLUMINESCENCE DOSIMETERS TO HIGH-ENERGY ELECTRON-BEAMS USED IN RADIOTHERAPY

To ensure the effectiveness of radiation-therapy treatments, both in-phantom and in-patient reliable dose measurements are required. Thermoluminescence dosimeters are used commonly for both applications. Among the various available materials, the relatively new LiF: Mg, Cu, P phosphor is a suitable candidate for quality control of in vivo dosimetry in electron-beam therapy. The response behaviour of LiF:Mg, Cu, P chips to 6-21 MeV electron beams used in radiotherapy was studied. Batch homogeneity, dose linearity, sensitivity change after use, dose and dose-rate response, energy dependence and fading characteristics were investigated. The contribution from each factor to the overall uncertainty in dose measurement was evaluated. The results of this work show that the LiF:Mg,Cu,P chips are comparable to the commonly used LiF:Mg, Ti ones, and support their use for in vivo electron-beam dosimetry to an accuracy within +/-10%.