A: Incorrect. CR typically exhibits lower detection effiency and lower detective quantum efficiency (a measure of the information transfer from the input x-rays to the information content of the output image) chiefly due to thinner screens (compared to CsI structured phosphors) or lower atomic number (compared to Gd2O2S screens : Gd Z=53 versus BaFBr CR screens : Br Z=35)B: Correct. This is the main advantage of CR. A passive cassette-based imaging detector that emulates the screen-film paradigm allowing use of conventional imaging equipment and providing excellent positioning flexibility that active DR detectors in their current technology state cannot provide.C: Incorrect. This is the advantage of DR over conventional CR (not including the newer line-scan and mechanical CR automatic readers)D: Incorrect. The intrinsic (prior to sampling) resolution of CR is lower than that of scintillator and photoconductor-based DR units. This is easily discerned by the MTF curves of each modality. The reasons are chiefly due to the use of a structured scintillator (CsI) used for most DR indirect detector systems which confines the emitted light without spreading and the use of high voltage placed across the semiconductor materials of DR direct detector which actively collects the electron/hole pairs from spreading out during acquisition. Of all detector converters the semiconductor detector has the highest intrinsic spatial resolution.
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