Analysis by EPR measurements and spectral deconvolution of the dosimetric properties of lithium formate monohydrate

Abstract

Abstract In this study we analyze the Electron Paramagnetic Resonance “EPR” response of lithium formate monohydrate “LFM” irradiated by photons and electrons using a linear accelerator. EPR measurements were performed one day after irradiation and regularly during six months of storage. Both dosimetric curves using peak to peak technique and double integration method showed linear behavior. The time dependence indicates good stability of free radicals produced on this material. The determined measurable threshold dose is 0.55 Gy. For used energies, LFM dosimeters are more sensitive to X-ray irradiation than to electrons. The deconvolution of the EPR signal of irradiated LFM using Levenberg-Marquardt (M-L) algorithm shows that this spectrum is constituting of three gaussian contributions. Each contribution has a linear evolution according to the irradiation dose, as well as an acceptable degree of stability during the storage period, approving the stability of all free radicals produced in LFM. All these characteristics confirm that LFM might be a promising dosimeter to be used in the ‘clinical’ dose range in radiotherapy.