AN ANALYTICAL EDGE SPREAD FUNCTION MODEL FOR COMPUTER FITTING AND SUBSEQUENT CALCULATION OF THE LSF AND MTF

The previous work of Yin, Giger, and Doi [Med. Phys. 17, 962-966 (1990 )] demonstrated that using a computerized fit of an analytic line spre ad function to experimentally measured data is very useful for determi ning the presampling modulation transfer function of an imaging system . In this report, the work of Yin et al. is extended to include an ana lytic expression for the edge spread function (ESF). By fitting experi mentally determined edge spread function data to the analytical expres sion, the normalized line spread function (LSF). and the normalized mo dulation transfer function (MTF) can be easily calculated from four ES F fit coefficients. The extension from the line spread function to the edge spread function should be valuable in cases where slit measureme nts are impractical, for example, in very high resolution imaging syst ems where the required slit dimensions become impractically small, or in measurements of the transfer properties of scattered radiation or o ff-focus radiation, where large area exposures are necessary.