Each of two detectors used in our Positron Emission Mammography (PEM) system consists of four 36mm x 36mm x 20mm bismuth germanate (BGO) detector blocks coupled to a crossed-wire anode photomultiplier tube (PMT). To achieve a high spatial resolution, the crystal blocks have been finely pixelated using a diamond saw. In each detector, 36 x 36 1.9mm x 1.9mm crystal elements are coupled directly to the PMT window and, on the opposite face of the blocks, 35 x 35 elements are offset by 0.9mm along both the x- and y-axes of the PMT. Techniques developed for the successful machining and surface-preparation of the detector blocks are described. Results indicating the detector block performance in terms of spatial and energy resolution are presented. / As part of a system calibration routine, a novel method for crystal element identification has been developed. This robust and reproducible algorithm succeeds in identifying 59 x 49 crystal elements on each detector face. The results are used to generate a Look-Up-Table (LUT) that is accessed during data acquisition for the effective correction of spatial distortion inherent in the detectors. Crystal identification also facilitates an improvement of the capability for accurate energy discrimination, since the detector gain and energy resolution are considered on an element-by-element basis by accessing an energy LUT. Employing a third LUT, which contains the relative efficiencies of individual crystal elements results in a significant improvement in detector uniformity.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.27395 |
| Date | January 1996 |
| Creators | Robar, James L. |
| Contributors | Thompson, C. J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Medical Radiation Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001549298, proquestno: MQ29770, Theses scanned by UMI/ProQuest. |
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