Resolution limit in positron emission computed tomography

There are two fundamental factors limiting the spatial resolution in developing high resolution positron emission tomographs. One is the finite range of positrons before annihilation and the other the deviation from 180 degrees of annihilation photons. The purpose of this paper is to evaluate the effect of the factors on the spatial resolution in reconstructed images. Since line spread functions allow to make the evaluation free from slice thickness, the line spread functions in projection for positron range and angular deviation were calculated from experimental data in leteratures. The physical limitations of the spatial resolution in reconstructed images were estimated for line sources of 11C, 68Ga and 82Rb positioned on the central axis of circular ring detectors, as a function of ring radius ranging from 10 to 50 cm. (author)