Multisegment slant-hole single photon emission computed tomography

In this dissertation, we have designed and evaluated a novel collimator as well as a novel imaging geometry that can increase the sensitivity of the single photon emission computed tomography (SPECT) system by 260%. The novel collimator, called the multisegment slant-hole (MSSH) collimator, was built by dividing a slant-hole collimator into multiple segments and arranging them such that the volume of interest (VOI) is projected multiple times onto the detector. Thus, depending on the number of segments used, the MSSH SPECT system results in a proportional increase in sensitivity compared to a parallel-hole SPECT system for the same acquisition time. Though we investigate the properties of the MSSH system specifically for cardiac imaging, the concept can be expanded for imaging other organs such as the breast and brain.; The MSSH data, obtained by rotating the SPECT camera around the longitudinal axis of the patient, were reconstructed using iterative as well as analytical reconstruction algorithms. Image degradation factors such as geometric response function (GRF) and attenuation were modeled and compensated for during the reconstruction. The GRF of the MSSH collimator was found to be asymmetric and depth dependent. This GRF was modeled and verified using physical phantom experiments. Quantitative comparison of the reconstructed images for the simulation studies shows that the MSSH system outperforms a comparable parallel-hole SPECT system, in terms of statistical noise and bias, thereby improving the detectability of small lesions with low contrast.; Apart from the iterative reconstruction algorithm, we also derived and implemented a novel analytical reconstruction algorithm for the MSSH imaging geometry. Since the MSSH imaging geometry can be considered to be made up of a set of circular arcs, we first derived a novel ‘closed form three-dimensional filter’ for the imaging geometry consisting of a single arc. This filter derivation is significant as the analytical reconstruction algorithms for a wide range of imaging geometries that can be broken down into a set of circular arcs can now be determined. The analytical reconstruction algorithm for such imaging geometries was previously considered too tedious to derive and hence was never used for medical imaging.; Finally, physical phantom studies were performed using a prototype MSSH collimator. Though the prototype system lacks safety features that are essential for animal or patient studies, the preliminary studies performed provided insight regarding patient positioning, field of view and three-dimensional reconstruction of real data. The improved reconstructed images obtained using MSSH SPECT show that MSSH SPECT has the potential of becoming the modality of choice for cardiac SPECT imaging.