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Fedrigo, Roberto

University of British Columbia

Theranostics has established itself as a promising field for diagnosis and treatment of cancer. Positron emission tomography (PET) is used to assess the initial tumour burden and to select candidates for therapy. Meanwhile, single photon emission computed tomography (SPECT) is used to determine the amount of dose that has been deposited during radiopharmaceutical therapy, allowing us to monitor the effects of treatment in real-time and plan subsequent treatments. Due to the importance of PET and SPECT imaging in radiopharmaceutical therapy, there is a need to validate scanner performance with precisely defined ground truth. Phantoms are the gold-standard for evaluating new imaging techniques, as they provide a controlled environment, where everything is known, that mimics the properties of a human subject without posing a risk to patients. However, few phantoms emulate the anatomical structures and biodistributions observed in human subjects. In this thesis, we develop and implement a wide range of anthropomorphic phantoms for quantification of ¹⁸F-PET and ¹⁷⁷Lu-SPECT imaging for dosimetry. We evaluate radiopharmaceuticals targeting prostate-specific membrane antigen (a biomarker found on prostate cancer cells) using a combination of physical and digital phantoms, although these techniques are applicable to a wide range of imaging tasks and malignancies. For physical phantoms, we developed shell-less radioactive spheres for a novel quality assurance phantom in ¹⁸F-PSMA PET imaging. To establish realistic organ models, we designed a novel casting method which may be used to manufacture custom phantoms from a reverse injection molding process. These techniques culminated in a first-of-its-kind theranostics phantom for ¹⁸F-PET and ¹⁷⁷Lu-SPECT imaging, such that the information from the higher quality PET images can be used towards improving image-based dosimetry with SPECT. Finally, we established a digital twins pipeline which may be used to simulate PET and SPECT images for virtual clinical trials. Overall, this thesis presents a wide range of anthropomorphic phantoms for quantification of PET and SPECT imaging in radiopharmaceutical therapies. The overarching aim is to enable better understanding of absorbed dose-effect relationships for tumours and organs-at-risk, paving the way for personalized radiopharmaceutical therapies, and improved management strategies and survival outcomes for patients with metastatic cancer.

Text

2025-01-31

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85184

Medical Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/