The main objective of this project is the development and evaluation of image reconstruction methods for a rotating, strip gamma camera for SPECT (single photon emission computed tomography). The strip gamma camera consists of a CdZnTe detector and a tungsten slat collimator. This solid-state detector is photomultiplier-tube free and has higher energy resolution (about 3% FWHM at 140 keV photopeak) than a regular Anger camera. In order to reduce the cost of CdZnTe material, the detector is a narrow rectangular strip. Instead of using a parallel-hole collimator, a set of parallel slats that define a series of planes are used to collimate the incoming photons. As a result, the measured projection data are planar integrals as opposed to the line integrals that are generally encountered in traditional Anger camera applications. The measured planar integral of the radioactivity distribution is weighted by a factor l/r, where r is the distance from the point of interest to the detector. One important goal of this proposal is to develop reconstruction algorithms that can exactly compensate for the detectors distance dependent sensitivity. Another important goal of this proposal is to develop algorithms that make the images immune from truncation errors. This will make our imaging system a local tomographic device. Still another important goal of this proposal is to evaluate the performance of the combination of the new detector and reconstruction algorithms. Special emphasis will be placed on developing a novel solid-state imaging system that will provide nearly scatter-free and truncation-error-free images. High image spatial resolution will be achieved by using convergent slat collimators. The work has the potential to significantly improve the diagnostic capabilities of SPECT imaging. This proposal will (a) promote the development of very novel (high risk, high gain) technologies, including continued support for their maturation and full exploitation, (b) promote system integration of technologies for targeted applications, and (c) improve technology transfer by promoting partnerships between academia and industry.
