INITIAL CHARACTERIZATION OF A PROTOTYPE MULTICRYSTAL CYLINDRICAL SPECT SYSTEM

A prototype SPECT system has been constructed to demonstrate the performances of a new multi-slice design for high resolution imaging. The system consists of a stationary cylindrical detector comprised of multiple bars of NaI(TI) scintillator, and a rotating collimator. The collimator consists of an assembly of multi-holed modules arranged with a four quadrant symmetry. The collimator modules are individually focused for discrete sampling in the transverse plane but parallel collimated for continuous sampling in the axial direction. Fan beam sampling for each detector bar in the transverse plane is accomplished after a 360-degrees rotation of the collimator. An array of photomultiplier tubes (PMTs) coupled to the outside of the detector cylinder identifies the bar and the axial position along the bar for each detected event. The current performance of this prototype system has been evaluated. The useful imaging volume has a circular cross section (20 cm diameter) with a 5 cm axial field-of-view. The average local energy resolution is 11.5% and the system sensitivity is 800 cps/muCi/cc/cm. The spatial resolution in the reconstructed plane is 8 mm FWHM. The tomographic images of resolution and anthropomorphic phantoms demonstrate high image quality.