Method for Determining the Point Spread Function for a Digital Radiography System

The shape and size of the projection of the focal spot of an x-ray tube largely depend on the direction of the beam, which results in a spatial difference of the point spread function (PSF) of the imaging system. A model developed for determining the PSF at an arbitrary point of the radiation field is presented in this article. The input data for the model are the geometric parameters of the system, the measured magnified projection of the effective focal spot, and the PSF in the internal structure of the detector. The difference in the width of the profiles of the PSF between the experimental and modeled data does not exceed 7.2%. The projection images are reconstructed by means of a deconvolution algorithm using the modeled PSF. The frequency–contrast characteristics of the images show improvement compared with the initial image.