Absolute MBF can be measured with good repeatability using FlowQuant analysis of (82)Rb PET scans with a 6-minute scan time, iterative reconstruction, dual SOC, RPP-adjustment, and an image-derived input function in the left atrium cavity.

T e s t-R e te s t R ep e ata b ility of M y o c a r d ia l B lo o d F lo w M e a s u re m e n ts using R u b id iu m -82 P o s itro n Emission T o m o g ra p h y by M atthew Efseaff, B.A. A Thesis Submitted to

For many years cavity ionization chambers have been the preferred detectors for measuring absorbed dose from ionizing radiation. Cavity theory formalisms relate the detector signal to a dose in the surrounding medium. Common cavity theories are straightforward to calculate but make limiting assumptions about charged particle fluences in the chamber and the medium. The choices that make them accurate are conceptually ambiguous and unrelated to physics first principles. This prohibits their general application across a wide range of physical conditions.A novel general cavity theory is introduced which addresses some of the previous limiting assumptions of existing formalisms by explicitly determining the perturbation of charged particles in the medium due to the chamber cavity. This cavity theory removes the ambiguity and derives from first principles at the expense of increased complexity. The formalism converges to the Spencer-Attix cavity theory in the limit of Bragg-Gray conditions and to the ratio of mass-energy absorption coefficients in the large cavity limit.The EGSnrc Monte Carlo simulation software is used to determine the expected dose ratios from full chamber dose calculations and to generate the input quantities to the novel formalism with regard to the air kerma formalism under Fano conditions. For 1.25 MeV incident photons the formalism is within 0.1% of full chamber calculated dose ratios for materials with atomic numbers 4 ≤ Z ≤ 29, between 0.2-0.7% at 300 keV, and between 0.8-5.3% at 50 keV. Formalism dose ratios calculated from cobalt-60, and 120 kVp x-ray, spectra showed similar agreement with full chamber calculated dose ratios as the mono-energetic cases.This new cavity theory is shown to be five times more accurate, on average, than Spencer-Attix for cavity heights of 1.39 mm, and 2.3 times more accurate, on Dr. Daniel La Russa, for their support and guidance during my time at the Ottawa Hospital. Together they offered wisdom and expertise throughout this journey. Daniel never hesitated to lend a hand with the hard work, dive into the details of the project, and help solve the confusing parts. I am thankful and indebted to them for their efforts.Many thanks to my wife, Janet, for her love, support, and encouragement. She kept our family happy, together, and fun during the long hours of research -especially through the Covid-19 lockdowns. She has 'pushed me to the top' throughout my two graduate degrees and soon it will be her turn to pursue a passion. Thank you is due to Dr. Paul Johns. He was the first person I met at Carleton University in 2009 when I started my Masters degree and he happens to be retiring the year I finish my Doctorate. We had a good number of meetings through the years and I always felt that he took a special interest in me. He was kind, gave good counsel, and embodied what it meant to be a seeker of knowledge. A big thank you to Dr. Reid Townsen at the NRC for his help in navigating the software I used in this research. I would also like to acknowledge my mother, Diane E...