The block effect in Positron Emission Tomography (PET) is the degradation in spatial resolution that is seen when there are more scintillation crystals than photomultiplier tubes in a detector. / We measured the block effect in detectors from three PET scanners: the Siemens-CTI HR+, the GE Advance, and the Siemens-CTI HI-REZ. In the CTI HR+ the block effect was 0.7 mm in the central crystals, and negligible for the edge crystals. In the GE Advance the block effect was 0.6 mm for the central crystals, and 0.5 mm for the edge crystals. In the CTI HI-REZ detector the block effect varied from 0.5 mm to 2.1 mm depending on the crystal location. / The effect of changing the depth of the first point of gamma-ray interaction in the block detectors was examined. The gamma-ray interaction depth was varied, and the event position in the crystal identification image was examined. If the events were positioned inconsistently with gamma-ray interaction depth, this might be a cause of the block effect. / In the CTI HR+ detector and the CTI HI-REZ detector, the positioning of events in the crystal identification image was dependent both on the crystal depth of the first point of interaction and the crystal location. In the GE Advance block detector the positioning of events in the crystal identification image was consistent for varying gamma-ray interaction depth, and crystal position. / In crystals where the positioning of events is not consistent with interaction depth, the block effect is larger. In the GE Advance block detector, another cause of the block effect may exist.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.84076 |
| Date | January 2005 |
| Creators | St. James, Sara |
| 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: 002261452, proquestno: AAIMR22768, Theses scanned by UMI/ProQuest. |
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