Time Modulated Apertures for Tomography in Nuclear Medicine

This paper presents techniques for overcoming the shortcomings inherent in known methods for imaging three-dimensional ¿-ray sources as encountered in nuclear medicine. Conventional pinhole and collimator cameras have low efficiency and do not display depth information. Coded aperture systems have high photon collection efficiencies, but their noise performance is worse than that of conventional apertures for sources of interest. Multiple view systems, with either cone beam or transverse axial geometries, have low efficiencies. This paper presents a general theory for increasing the efficiency of such multiple view systems. Source dependent time-modulated apertures are used. In other words, a particular modulating function is chosen according to the characteristics of the source being imaged. A statistically optimal demodulating method is used. The final image is that of a chosen source plane, without the out-of-focus background produced by other imaging methods.