Initial characterization of a prototype multi-crystal cylindrical SPECT system

A prototype SPECT (single photon emission computed tomography) system was constructed to demonstrate the performances of a novel multislice design for high-resolution imaging. The system consists of a stationary cylindrical detector composed of multiple bars of NaI(Tl) scintillator and a rotating collimator. The collimator consists of an assembly of multiholed 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 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 was 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/ mu Ci/cm/sup 3//cm. The spatial resolution in the reconstructed plane is 8 mm FWHM (full width at half maximum). The tomographic images of resolution and anthropomorphic phantoms demonstrate high image quality.<>