Evaluation of a brain imaging system with combined parallel hole and pinhole collimation

This work evaluates the brain imaging system designed by the Department of Investigative Radiology at the National Cardiovascular Research Center - Research Institute in Osaka, Japan. As presented at the IEEE Nuclear Science Symposium and Medical Imaging Conference at Knoxville, TN in 2010, the high resolution single photon emission computed tomography (SPECT) imager was developed for obtaining high resolution brain scans for various imaging diagnostic applications. The system was mounted with one large field of view detector imaging the whole brain and multiple smaller field of view high resolution detectors imaging small regions of the brain. The large field of view detector provides images without truncation that localize areas of particular diagnostic interest and provide support information for the reconstruction of high resolution regions of interest (ROIs) from high resolution truncated projections obtained with the small field of view detectors. At the IEEE conference, the authors suggested a geometry which achieved high resolution reconstruction of the brain with a small pinhole aperture. The work presented in this paper simulates the camera with larger pinholes and shows that the camera has accurate quantitation and fine resolution for the interior reconstruction problem. (orig.)