Correction for compton scattering by analysis of energy spectra

Abstract

A system for removing the effects of Compton scattering in systems such as tomographic scanning and radioisotope imaging arrangements, which detect gamma rays, utilizes the smoothness of the Compton component over the image to reduce computing time. Data responsive to energy states of the photons which are detected are received and values corresponding thereto are stored in at least one memory location. In some embodiments, where imaging is the ultimate function of the gamma ray detection system, the data correspond to predetermined image grid points. Also, the data which is stored is processed so as to be separated into a first data set corresponding to unscattered ones of the detected photons and a second data set corresponding to scattered ones of the detected photons. The gamma ray detection arrangement is calibrated by acquiring a spectral shape corresponding to unscattered photons. The processing utilizes non-linear least squares fitting analysis. The first data set is summed within specified limits, for determining a number of the unscattered ones of the detected photons. A scatter-free image can then be formed from this data set.