A characterization of the scatter point-spread-function in terms of air gaps

Characterizing the scatter point-spread-function (PSF) yields a model for predicting the behavior of the scatter and a PSF for deconvolution techniques that correct for scatter. Assuming the X-ray scatter is isotropic, the authors present a model for the scatter point-spread-function parameterized only by air gap. This model suggests that small increases in air gap significantly attenuate the higher-frequency structure of the scatter distribution. To evaluate this model, the authors examined the behavior of the spatial frequency distributions of experimental scatter images as a function of air gap. Using film as the detector, they imaged a 20-cm uniformly thick water phantom with aperture diameters of 8, 12, 16, 20, and 24 mm at air gaps of 0-24 cm.