A Monte Carlo study of primary electron production inside photoconductors for digital mammography and indications of material suitability

作者：Sakellaris T^*; Spyrou G; Panayiotakis G; Tzanakos G

来源：Journal of Instrumentation, 2010, 5: P08004.

DOI：10.1088/1748-0221/5/08/P08004

• Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc)
• X-ray mammography and scinto- and MRI-mammography
• Materials for solid-state detectors

Materials like a-Se, a-As(2)Se(3), GaSe, GaAs, Ge, CdTe, CdZnTe, Cd(0.8)Zn(0.2)Te, ZnTe, PbO, TlBr, PbI(2) and HgI(2) are possible photoconductors for direct conversion digital mammography detectors. The physical characteristics of primary electrons, such as their number, energies, direction angles and spatial distributions, strongly affect the characteristics of the final signal and hence image quality. In previous work, a Monte Carlo model has been developed that simulates the generation of primary electrons inside these materials for x-ray spectra in the mammographic energy range. Using this model the energy, angular and spatial distributions of primary electrons have been studied. For the case of CdTe, CdZnTe, Cd(0.8)Zn(0.2)Te and ZnTe, an investigation was also made concerning the dependence of the primary electron production on the incident x-ray energy. In this paper, this investigation has been extended to include the rest of the photoconducting materials. The investigation is realized studying the number of primary electrons produced along with the escaping of photons (both incident and fluorescent) and the number of fluorescent photons emitted for 39 monoenergetic x-ray spectra with energies between 2 and 40 keV. The information obtained from the overall investigation of the primary signal in the various photoconductors gives some good indications of the suitability of PbI(2) and HgI(2).