Motivated by the need to standardize preclinical imaging for image-guided radiation therapy (IGRT), we examine the parameters that influence microcomputed tomography (microCT) scans in the realm of image quality and absorbed dose to tissue, including therapy beam measurements of small fields.
Preclinical radiation research aims to understand radiation-induced effects in living
tissues to improve quality of life. Small targets and low kilovoltage x-rays create challenges that do not arise in clinical radiation therapy.
Evidence based on our multi-institutional study reveals a considerable aberration
in microCT image quality from one institution to the next. We propose the adoption
of recommended tolerance levels to provide a baseline for producing satisfactory and
reproducible microCT image quality scans for accurate dose delivery in preclinical
IGRT.
Absorbed dose imparted by these microCT images may produce deterministic effects that can negatively influence a radiobiological study. Through Monte Carlo (MC) methods we establish absorbed microCT imaging dose to a variety of tissues and murine sizes for a comprehensive combination of imaging parameters. Radiation beam quality in the small confines of a preclinical irradiator is also established to quantify the effects of beam scatter on half-value layer measurements.
MicroCT scans of varying imaging protocols are also compared for murine subjects.
Absorbed imaging dose to tissues are established and presented alongside their respective microCT images, providing a visual bridge to systematically link image quality and imaging dose.
We then characterize a novel small plastic scintillating dosimeter to experimentally measure microCT imaging and therapy beams in real-time. The presented scintillating
dosimeter is specifically characterized for the low energies and small fields found in
preclinical research. Beam output is measured for small fields previously only achievable
using film. Finally, quality assurance tests are recommended for a preclinical IGRT unit.
Within this dissertation, a narrative is presented for guiding preclinical radiotherapy
towards producing high quality microCT images with an understanding of the absorbed imaging dose deposited to tissues, including providing a tool to measure small radiation fields. / Graduate
| Identifer | oai:union.ndltd.org:uvic.ca/oai:dspace.library.uvic.ca:1828/10789 |
| Date | 29 April 2019 |
| Creators | Johnstone, Christopher Daniel |
| Contributors | Bazalova-Carter, Magdalena |
| Source Sets | University of Victoria |
| Language | English, English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
| Rights | Available to the World Wide Web |
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