Paul Brewer

SPECT-CT system for small animal imaging

The Detector Group at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) and the Biology, Physics, and Applied Sciences Departments at the College of William and Mary are collaborating on the development of a miniature dual modality SPECT-CT system for mouse imaging. The detector heads of the SPECT sub-system are designed to be capable of imaging the gamma- and X-ray emissions (28-35 keV) of the radioactive isotope iodine-125 (I-125). Two different sets of I-125 imaging detectors are configured on a gantry that has an open-barrel type design. One set of detector heads is based on the 1-in square Hamamatsu R5900-M64 position sensitive photomultiplier tube coupled to crystal scintillator arrays. The other detector heads configured on the gantry are two 5-in diameter Hamamatsu R3292-based compact gamma cameras. The X-ray radiographic projections are obtained using a LIXI Inc. model LF-85-503-OS X-ray imaging system that has an active area of 5.5 cm in diameter. The open-barrel shaped gantry facilitates the positioning of various mini gamma-ray imaging detectors and the X-ray system. The data acquisition and gantry control is interfaced through a Macintosh G3 workstation. Preliminary SPECT reconstruction results using the R5900 based detector are presented.

An economical dual-modality small animal imaging system with application to studies of diabetes

We have developed an economical dual-modality nuclear imaging system comprised of two Hamamatsu 125 mm diameter position sensitive photomultiplier tubes (PSPMT) viewing pixelated scintillators and a small fluoroscopic X-ray system (Lixi, Inc.). Collimators placed between the animal and the scintillators can be readily interchanged and include CuBe parallel-hole collimators with a range of resolution/sensitivity combinations as well as brass pinhole collimators with various pinhole diameters. The small X-ray fluoroscope provides 5 cm diameter images, several of which can readily be combined to provide structural information from the animal under study. The system has been used to follow the metabolism of compounds tagged with /sup 125/I. Biological information has been obtained on the uptake of tagged insulin and tumor necrosis factor-alpha (TNF/spl alpha/) thus demonstrating the applicability of this system for in vivo analysis of diseases such as diabetes.