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 spread function to experimentally measured data is very useful for determining the presampling modulation transfer function of an imaging system. In this report, the work of Yin et al. is extended to include an analytic expression for the edge spread function (ESF). By fitting experimentally determined edge spread function data to the analytical expression, the normalized line spread function (LSF) and the normalized modulation transfer function (MTF) can be easily calculated from four ESF fit coefficients. The extension from the line spread function to the edge spread function should be valuable in cases where slit measurements are impractical, for example, in very high resolution imaging systems where the required slit dimensions become impractically small, or in measurements of the transfer properties of scattered radiation or off-focus radiation, where large area exposures are necessary.