Effective energy resolution and scatter rejection in nuclear medicine

All available imaging devices in nuclear medicine have finite energy resolution. This leads to inclusion of scattered radiation, which in turn degrades the image quality. Different scatter correction schemes therefore try to eliminate the effect of scattered radiation. On the other hand, improvement of the camera's intrinsic energy resolution would reduce the amount of detected scattered radiation as well. A simple model was developed in order to simulate the influence of the energy resolution on the camera response. It is shown that improvement of the energy resolution and scatter correction schemes have a similar effect on the point spread function. On this basis, it is suggested that 'effective energy resolution' be used as a new measure for the effectiveness of scatter correction schemes. As an example, this is done for energy-weighted acquisition (EWA), a scheme wherein each event contributes imaging information according to a real-valued, energy-indexed weighting function.