The work presented examined methods for improving image quality and the extraction of data from radionuclide images. The quality of images was improved by constructing equipment and developing techniques that performed time of flight (TOF) positron emission computed tomography (PECT). The merits of incorporating TOF into PECT have been assessed by measurement of temporal resolution, positional accuracy and variation in response of discrete radioactive line sources (RLS), together with estimation of contrast resolution (CR) from a simulated tomographic imaging system. The results demonstrated temporal resolution of 296 ps with good correlation between detected and physical locations of the RLS (r = 0.994). The coefficient of variation in full width half maximum (FWHM) was 22 per cent and the mean sensitivity of the system integrated between the FWHM of the RLS was 21.0 10-3 events s-1 MBq -1. The inclusion of TOF into a tomographic imaging system achieved a 43 per cent increase in CR with an additional improvement in image quality when a TOF filtered back projection technique was adopted. The accuracy and reproducibility of extracting numerical data from images has been examined by developing two edge detection algorithms (EDAs) for defining regions of interest (ROI) about an organ. The EDAs have been assessed by using computed simulations, radioactive phantoms, clinical studies and comparisons with other EDAs and methods of defining ROIs. The criteria of an EDA's response under varying imaging conditions have been established. The results show the factors which limit the application of EDAs and show that the EDAs developed improve correlation in measuring left ventricular ejection fractions with other imaging techniques and reduce intra- and inter-observer variation in comparison with other methods of defining ROIs. The combined use of EDAs and TOF positron emission tomography demonstrate the potential for improving the quantitation of data from radionuclide images.
|Date of Award||1982|