We will develop and evaluate methods for improving image quality in film-screen chest radiography, and we will investigate the feasibility of application of these improvements to digital imaging technologies. Three specific technical improvements include unsharp masking for optimal presentation and display of image contrast, highly efficient scatter cleanup by improved antiscatter grids or slit scanning, and dual-energy subtraction for bone vs. soft-tissue. We will also investigate the tolerable level of image degradation (e.g., decreased spatial resolution) that can be tolerated in implementing these techniques with digital imaging devices, e.g., scanned projection radiography or large-field image intensifiers. This combination of technical improvements may provide an optimal chest radiograph, with significant benefits in diagnostic accuracy over conventional techniques. Evaluation will be by measurements of physical parameters of image quality, phantom-nodule detection studies, and clinical studies of cancer patients at risk for primary or metastatic lung cancer.