title: Energy absorbed in calcium tungstate x-ray screens.
abstract: The energy which must be absorbed in a CaWO4 x-ray intensifying screen to produce unit net opetical density on a film has been evaluated by measurement and calculation for a screen-film system over a range of beam qualities (1.4--7.4 mm A1 HVL) spanning the diagnostic x-ray region. It was found to be constant within experimental error. The absorbed-energy constant for three additional CaWO4 screens is presented for a single beam quality. To correct the estimation of absorbed energy, the fractional escape of tungsten K x rays has been evaluated and the results are presented as a function of phosphor loading. The absorbed-energy constant is useful for predicting optical density for variable beam conditions; a family of characteristic curves based on exposure is reduced to one curve for a particular film-screen system, expressed as optical density as a function of absorbed energy.
mesh_terms: D002118:Calcium; D011856:Radiographic Image Enhancement / Q000295:instrumentation*; D013679:Technology, Radiologic; D014414:Tungsten; D014894:Weights and Measures
chemical_list: D002118:Calcium; D014414:Tungsten