Date of Award
2007
Degree Type
Thesis
Degree Name
Master of Science
Program
Physics
Supervisor
Blaine A. Chronik, Ph.D.
Abstract
Dual-modality SPECT-MRI allows the functional imaging benefits of SPECT to be overlaid on the high-resolution structural images for which MRI is known. The two modalities, however, do not coexist easily. This study examines the viability of per forming pinhole-SPECT via an array insert within an existing field-cycled MRI scan ner. The purpose of this investigation is to determine the magnitude and distribution of additional scatter introduced into the SPECT data by the presence of the field- cycled MRI hardware.
An insert consisting of twelve lead collimators with tungsten single-pinhole aper tures was designed for imaging a 1-cm-radius spherical volume. A Monte Carlo sim ulation was implemented incorporating the geometry of the field-cycled MRI and the pinhole collimators. The simulated source phantom contained seven point-sources distributed along the x— and 2—axes within a cube of water. An ordered-subset expectation-maximization algorithm was used to reconstruct the simulation results into tomographie slices.
The efficiency of the collimator array in the field-cycled MRI was found to be (2.015±0.002) × 102sounts with a spatial resolution between 1.47 and 1.81 mm FWHM. The principle artefact was a shell of reconstructed activity just outside the sensitive volume due to the aluminum cooling plates required by the field-cycled MRI.
Recommended Citation
Odegaard, James William Kristian, "Design and Performance Evaluation of a Small-Animal Pinhole-SPECT Array Insert for Field-Cycled MRI" (2007). Digitized Theses. 4965.
https://ir.lib.uwo.ca/digitizedtheses/4965