The relative sensitivities of contemporary scanning techniques

The purpose of this article is to compare the relative sensitivities of current instrumentation in radionuclide emission tomography, i.e. SPECT and PET. The resolution in each of these devices is approximately the same (<7 mm FWHM best performance for SPECT, 6mm FWHM for PET). The sensitivity gain of the PET directly contributed to improved signal-to-noise ratio and better image quality than the SPECT, in spite of differences in amount of dose administered, uptake, and acquisition time. Clearly, the sensitivity issue remains the one area where single photon techniques still lag significantly behind. It is estimated that the electronic collimation idea of the mid-80s in SPECT, where the conventional lead collimator is replaced by an array of semi-conductor detectors that detect the point of transmission of a photon but cause minimal scattering, thus providing two points to which is assigned a single line-of-response, will eventuate one day when suitable semi-conductor materials become inexpensive and readily available. 3 refs., 1 tab., 1 fig