The Nuclear Medicine Department (NMD) of the Clinical Center has developed a small field-of-view (FOV) gamma camera which has great promise for practical, high-resolution imaging of small animals. The system is based on a single position-sensitive photomultiplier tube (PMT). Unfortunately, the position-sensitive PMT does not possess either a linear voltage analog of event position, or a uniform energy response across the tube face. We have developed a Multibus II Image Correction System, comprised of three coupled 386/486 processors, which allows first-order, geometric and energy corrections to be performed sequentially, in real-time on data from the small FOV gamma camera. The Image Correction System acts either as a standalone, two-processor data acquisition system for the small FOV gamma camera, or it is interposed between this camera and a commercial analog acqusition system, and used as a three-processor system. The three processors are dedicated to input (analog-to-digital conversion), computation (geometric, energy and motion correction), and output (digital-to-analog conversion or digital transmission), respectively. Software for system control, data acquisition, corrected and uncorrected image display, and data/image transmission has been developed. All geometric and energy correction software has been completed. Work has begun on the implementation of new algorithms for image acquisition in PET scanner mode, which are suitable for use in imaging the human breast. The Kinahan and Rogers 3D PET reconstruction algorithm was ported from the Sun SPARCstation to the Macintosh. The programs which support breast imaging were modified for use with these algorithms, in new experiments. In addition, The Polhemus Systems 3Space Tracker, an electromagnetic position/orientation measurement system, was integrated into the Multibus II System.
