THE CONTRAST-DETAIL BEHAVIOR OF A PHOTOSTIMULABLE PHOSPHOR BASED COMPUTED RADIOGRAPHY SYSTEM

Contrast-detail measurements were performed on a computed radiography imaging system as a function of detector entrance air kerma over the d ose range from 0.743 mu Gy (0.085 mR) to 277 mu Gy (31.8 mR). A theore tical model of contrast-detail behaviour for a photostimulable phospho r computed radiography system has been derived, which is based on a mo dified version of the Rose theory of threshold detection. Included in the model are both system and x-ray quantum noise terms, as well as th e response of the eye. The zero-frequency noise power of the computed film images was measured with a double-beam scanning microdensitometer . For a given detector dose, good agreement was found between the pred icted and measured data when this measurement of system noise was incl uded in the model. The contrast-detail results obtained for the comput ed radiography system were also compared with contrast-detail results for an image intensifier-TV based digital imaging system and a convent ional film-screen system.