Measurements of the physical performance of a prototype digital chest unit (DCU) are presented. The parameters evaluated were entrance skin exposure, system exposure response and dynamic range, system modulation transfer function (MTF), image noise levels, detective quantum efficiency (DQE) of the detector and scatter suppression efficiency. Compared with conventional chest imaging systems, the unit has markedly greater exposure latitude, limited spatial resolution, a lower detector DQE, and virtually scatter-free images. Routine clinical exposure levels are comparable with the 1982 national average.
