  Single Photon Emission Computed Tomography (SPECT) is a non-invasive imaging
modality, frequently used in myocardial perfusion imaging. The biggest
challenges facing the majority of clinical SPECT systems are low sensitivity,
poor resolution, and the relatively high radiation dose to the patient. New
generation systems (GE Discovery, DSPECT) dedicated to cardiac imaging improve
sensitivity by a factor of 5-8. The purpose of this work is to investigate a
new gamma camera design with 21 hemi-ellipsoid detectors each with a pinhole
collimator for Cardiac SPECT for further improvement in sensitivity,
resolution, imaging time, and radiation dose. To evaluate the resolution of our
hemi-ellipsoid system, GATE Monte-Carlo simulations were performed on
point-sources, rod-sources, and NCAT phantoms. The purpose of point-source
simulation is to obtain operating pinhole diameter by comparing the average
FWHM (Full width half-maximum) of flat-detector system with curved
hemi-ellipsoid detector system. The operating pinhole diameter for the curved
hemi-ellipsoid detector was found to be 8.68mm. System resolution is evaluated
using reconstructed rod-sources equally spaced within the region of interest.
The results were compared with results of GE discovery system available in the
literature. The system performance was also evaluated using the mathematical
anthropomorphic NCAT (NURBSbased Cardiac Torso) phantom with a full (clinical)
dose acquisition (25mCi) for 2 mins and an ultra-low-dose acquisition of 3mCi
for 5.44mins.
