Cumulative dose experiments on Lithium formate monohydrate as an EPR-dosimeter for use in different radiation therapy scenarios

Abstract

The Electron Paramagnetic Resonance (EPR) method can be employed to read out the absorbed dose of suitable materials exposed to ionizing radiation. In this work, we study the dosimetric properties of lithium formate monohydrate (LFM) irradiated by X-rays, electrons and protons in order to use it as dosimeter in radiotherapy, including hadrontherapy. The responses of the cumulative doses received by a single dosimeter were analyzed in order to investigate the feasibility and possibility of using a single dosimeter per patient for all therapy fractions. A perfect linearity of the LFM dosimetry curves is observed, with an acceptable degree of accuracy exceeding 99%. LFM seems to be slightly more sensitive to X-ray photons compared to proton and electron irradiations with a rate of about 16% and 10% respectively. The analysis of the effect of cumulative doses revealed acceptable accuracy and reliability of the results. Indeed, the dosimetry curves obtained with several dosimeters having received a single dose (reference curve) and those obtained with a single dosimeter having received several cumulative doses are completely superposable with relatively acceptable uncertainties, which is found to be less than 5%.