A new concept found successful for improving the image quality of computed radiography (CR) is presented. It is shown theoretically and experimentally that radiographic contrast and sharpness can be improved by reduction in scattered X-rays without increasing patient exposure. ST (imaging plate : IP) combined with high-ratio antiscatter grids (the Low-Scatter System : LSS) and low-ratio grids (the High-Scatter System : HSS) for general radiography, and HR (IP) combined with antiscatter grids (LSS) and without grids (HSS) for mammography, were used in this study. In LSS, radiographic noise can be increased by a factor of about 2 due to reduction in the incident dose to IP. However, radiographic contrast and response can also be increased by a factor of 1.4-1.6. Images by LSS were found to those by HSS in visual detection of low contrast test objects and also in clinical application. This method is simple and has the advantage of not requiring special devices such as a moving slit assembly.
