Novel detector developments for positron emission tomography

This thesis is primarily concerned with the development of novel detector techniques for Positron Emission Tomography (PET). In recent years, PET has evolved to the extent that the technique is routinely used to provide valuable quantitative information related to a variety of health care problems. A review of the concepts and techniques associated with PET imaging systems is presented, including the performance characteristics of current systems. This review concludes by highlighting a number of key design features that should be incorporated in new PET systems. Following this review, work is presented on the development of two novel PET detector systems that seek to meet some of these objectives. Both designs, though significantly different, have the potential to provide high resolution imaging (<2mm) with low dead- time (<100ns), a depth-of-interaction capability (5-10mm), a high packing-fraction and a minimal perimeter dead-space. Also, as a consequence of the novel fibre readout methods employed, the detector modules should prove to be very cost-effective. In addition to this, both detectors are capable of operation within the coil of an MRI scanner in order to co- register the PET data with a high-resolution anatomical image. The final chapter concerns an extensive study into the characterisation and analysis of the energy-resolution performance of arrays of small scintillation crystals. Such arrays are commonly used for both PET detectors and some gamma camera designs. This study was intended to provide insights into improving the energy-resolution through scintillator optimisation, and also to form the basis of an accurate detector-response function for such arrays. This could be used to apply a spectral-deconvolution technique that has recently achieved great success when applied to conventional gamma-ray spectrometers, improving the energy-resolution from 12% to 3% at 662keV. This spectral-deconvolution, if successfully applied to gamma cameras, might result in an energy-resolution performance comparable to that of current room temperature semi-conductor detectors. (author)