Research on a high-sensitivity small animal SPECT system

Geometric efficiency was used to derive the point spread function (PSF) of a SPECT system which uses no collimator. The thickness of the NaI crystal was also considered and a modification of the PSF was made. An experiment with the γ camera was used to support the derivation. It showed that the system had a high sensitivity and provided an acceptable image at the same time. Based on above results, the sensitivity and resolution of the no-collimator system was discussed to show the potential of the system in small animal imaging. Then Rose criterion was introduced to show that with a high sensitivity the influence of the noise was weakened and a better time resolution in dynamic imaging was provided. (authors)