Corrections for Attenuation, Scattered Radiation, and Random Coincidences in a Ring Detector Positron Emission Transaxial Tomograph

The effect of attenuation, scattered radiation and random coincidences were evaluated in a positron camera with 95 NaI-detectors. Experimental tests and computer simulations were performed to find the contribution of the various effects to the number of counts in each detector channel. Images were then reconstructed with and without corrections for the different factors and the errors in the images were quantified. It is shown that accurate quantitative measurements of regional concentration of radionuclides necessitate a proper correction for the different factors.