Attenuation and scatter are limiting factors in image quality and quantitation of organ function by single photon emission computed tomography (SPECT). To correct brain images for attenuation an effective water/tissue attenuation coefficient of 0.12 cm$ sp{-1}$ (at 140 keV) or larger has been recommended in order to compensate for the additional bone (skull) attenuation. / It has been determined that the reconstructed images are overcorrected in the centre by 5%, and the optimum correction occurs for a reduced coefficient of 0.09 cm$ sp{-1}$. The overcorrection is due to increased attenuation at the edges of all projections where the path length through the bone is greater, although the bone also increases the scatter at the projection edges. / A correction scheme which uses effective bone and water coefficients was developed to compensate for the attenuation. Alternatively, prior to attenuation correction, a common scatter correction was found to be effective in explicitly removing the bone and water scatter.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.59403 |
| Date | January 1989 |
| Creators | Kemp, Brad J. |
| 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: 001068872, proquestno: AAIMM63573, Theses scanned by UMI/ProQuest. |
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