Effect on DQE of screen energy weighting in mammography

摘要: Our work investigates the effect on zero-spatial-frequency DQE of indirect mammographic image receptors combined effects x-ray beam hardening and light photon transport within sensitive medium receptor. Beam hardening, in this context, refers to preferential absorption low-energy photons at surface detector which is incident, with deeper layers absorbing higher average energies. The properties both powder crystalline/columnar phosphors favor collection light-sensitive element generated closest that element. net result these two perform a weighting detected spectrum. For standard back-screen configuration used conventional mammography, x rays are more heavily weighted, matching energy dependence signal be detected. front-screen configuration, all existing indirect-detection digital systems, just opposite true. We have optical Monte Carlo simulation code DETECT-II determine efficiency pulse distributions for Min-R screen front- configurations, thicknesses CsI, as function energy. These data, along appropriately hardened spectra several anode filter combinations range tube voltages, were input task-dependent theory Tapiovaara Wagner.