Geiger-mode avalanche photodiodes, or silicon photomultipliers, are promising light sensors for the next generation Positron Emission Tomography (PET) scanners. The sensor is being used in the scanner’s gamma ray detector to measure scintillation light. This thesis describes the test results of three gamma ray detectors that utilize silicon photomultipliers. The first one is a commercial detector, and the other two are custom made. The detectors are tested for their 511 keV photon energy and timing resolution, as well as their ability to measure light from small scintillator crystals. The two custom made detectors had smaller active area, but outperformed the commercial detector in energy resolution. The introduction of buffer amplifiers improved the timing resolution of one detector. All three detectors had their crystal decoding ability limited by signal multiplexing and the sensor’s dark noise. Finally, a detector design was proposed for the PET system being developed in our group.

This dissertation outlines work taken towards the understanding, implementation, and improvements to the process of creating of quantitative images of the bulk-electrical parameters of the interior of unknown objects via the use of electromagnetic scattering data. Improvements are considered to both theory and experiments using low-power radiation in the microwave frequency range, known as Microwave Tomography (MWT). A detailed derivation of the Multiplicative-Regularized Contrast-Source Inversion (MR-CSI) method is given, and we compare the performance of MR-CSI with the other leading inversion technique used in MWT: the Gauss Newton/Distorted Born Iterative Method. The inversion results of the two algorithms are very similar, and thus most of the differences between them are in the relative ease of implementation and computational resource use. We further introduce a new version of the CSI algorithm, based on the Finite-Difference method. Using this algorithm, we show that when accurate information about a scatterer is known before the inversion process, this information is best utilized as an artificial computational background, as opposed to an initial guess of the scatterer. The MWT problem is also formulated inside of a conductive enclosure, which significantly changes the physics, and resultant Green's function, of the MWT problem. The implications and possible advantages of this type of MWT are discussed, and synthetic inversion results for a circular enclosed system are presented. These results show that the enclosure is capable of improving the inversion in some regions, although more research is required to realize the full potential of conductive-enclosure MWT. In the final section, experimental results from both open-region and conductor-enclosed type MWT systems developed at the University of Manitoba are shown. For the open-region system, we show that antenna coupling is a major factor affecting the data collection, and provide a simple method for avoiding the frequencies where this coupling is too strong to prevent effective imaging. For the conductor-enclosed type system, we have found the system to be extremely sensitive to presence of antennas in the chamber, and show that effective MWT imaging is possible in this type of system by taking the antenna elements into account in the inverse solver.

Objective: To develop a score for hematoma expansion prediction, identify predictors of outcome, and validated existing prognostic scores in acute intracerebral hemorrhage (ICH). Methods: Data were obtained from a prospective multicenter ICH cohort. Patients were evaluated with computed tomography (CT) angiography, 24-hour CT, and 3-month outcome. Multivariable regression identified predictors of 24-hour expansion and 3-month outcome and a score was developed for expansion prediction. Existing scores were evaluated in the dataset. Results: The PREDICT Hematoma Expansion Score predicts 24-hour expansion based on number of spots, stroke severity, time from onset, and coagulopathy (c-statistic: 0.803). Prediction was improved over spot sign presence (p<0.001) and clinical variables alone (p=0.002). Existing scores for hematoma expansion and clinical outcome demonstrated reduced discrimination compared with the original reports. Conclusion: The PREDICT Hematoma Expansion Score may aid patient selection for future interventions aimed at reducing expansion however external validation is required. Existing scores demonstrated reduced discrimination.

Objective: To develop a score for hematoma expansion prediction, identify predictors of outcome, and validated existing prognostic scores in acute intracerebral hemorrhage (ICH). Methods: Data were obtained from a prospective multicenter ICH cohort. Patients were evaluated with computed tomography (CT) angiography, 24-hour CT, and 3-month outcome. Multivariable regression identified predictors of 24-hour expansion and 3-month outcome and a score was developed for expansion prediction. Existing scores were evaluated in the dataset. Results: The PREDICT Hematoma Expansion Score predicts 24-hour expansion based on number of spots, stroke severity, time from onset, and coagulopathy (c-statistic: 0.803). Prediction was improved over spot sign presence (p<0.001) and clinical variables alone (p=0.002). Existing scores for hematoma expansion and clinical outcome demonstrated reduced discrimination compared with the original reports. Conclusion: The PREDICT Hematoma Expansion Score may aid patient selection for future interventions aimed at reducing expansion however external validation is required. Existing scores demonstrated reduced discrimination.

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The development of two different classes of optical sources for TD-OCT and FD-OCT are presented in this thesis. The design of several low-cost, high-performance BBSs, based on the ASE of two SOAs and EDF, are presented. Two different configuration types that were designed in this thesis are found to be effective BBSs. These sources are implemented in a TD-OCT system and therefore imaging performance is discussed as well. Secondly, two different WSSs based on mode-locked SFRLs with applications in SS-OCT are presented. / From our experimental results with BBSs, we conclude that: (1) S/C-band output produced by the ASE emitted from two cascaded SOAs can be effectively extended with L-band output produced from the ASE of EDF; (2) An even broader output is achievable by: coupling the C-band and L-band outputs from a C-band SOA and EDF respectively and then amplifying the coupled output through an S-band SOA; (3) OCT imaging systems employing a light source with an S+C+L band output, with a center wavelength of approximately 1520 nm, can achieve high penetration depths in biological tissue. / From our experimental results with SFRLs, we conclude that: (1) Our two SFRL configurations generate picosecond pulses with reasonably narrow linewidths: 0.2--0.5 nm, and a sweeping range of about 50 nm; (2) These SFRLs can function as laser swept sources by setting the driving frequency of the RF generator to a periodic ramping function.

This thesis is in the area of ultrasound tomography, which is a non-destructive imaging method that attempts to create quantitative images of the acoustical properties of an object of interest (OI). Specifically, three quantitative images per OI are created in this thesis, two of which correspond to the complex compressibility profile of the OI, and the other corresponds to its density profile. The focus of this thesis is on the development of an appropriate two-dimensional inverse scattering algorithm to create these quantitative images. The core of this algorithm is the Born iterative method that is used in conjunction with a fast and efficient method of moments forward solver, a Krylov subspace regularization technique, and a balancing method. This inversion algorithm is capable of simultaneous inversion of multiple-frequency data, and can handle a large imaging domain. This algorithm is finally tested against synthetic and measured data.