Application of coded apertures in tomographic head scanning

Abstract

A circular ring tomograph, designated SPRINT, is under development for single photon emission tomography of the human head. Most data to date have been gathered using a single rotating slit inside the detector ring to define ray directions. As an alternative method, we have also investigated the use of multiplexed slit patterns consisting of a pseudorandom binary code. From theoretical considerations, one would expect that the substitution of the code for the single slit would have potential advantages in reducing statistical noise in tomographic images of small objects. It has been our experience that this improvement is marginal at best for the types of source distributions encountered in clinical brain imaging. However, the code shows substantial advantage in suppressing uncorrelated backgrounds and the effects of highly penetrating gamma ray components in the source.