Low-E extension of a hand-held Compton spectrometer

The MICOS Compton spectrometer is a tool for the routine spectrometric control of X-ray generators, mainly in the medical field (<150 kV). The use of a pen-type NaI (Tl) detector with thin Be window allows to extend its range down to 6 keV, for a better evaluation of the low-E side of the spectrum, which is determined by filtration. A specific problem is encountered in the deconvolution of the spectrum at very low energies, dominated by the K escape of iodine. The proposed solution combines an approximate step-by-step application of the GRAVEL algorithm, whereas the MAXED unfolding software is used for reaching the final solution. A new computer code was developed that combines spectrum acquisition and deconvolution and calculates the main characteristics of the source spectrum: end point energy, mean energy, energy at 50% of the left slope, and air kerma at 1 m from the source.