Liquid Xenon detector for 10ps time of flight positron emission tomography

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Doctors rely heavily on medical imaging to assist them in the detection of various diseases in patients. Specifically, nuclear molecular imaging techniques such as positron emission tomography (PET) let us follow radioactive molecules that are injected in patients. These molecules interact - or not - with the body's chemistry. This, for example, allows oncologists to give an early diagnostic of cancer, before the tumour can be seen by other methods, as well as see if a cancer therapy is successful or not. PET imaging is also used to investigate new treatment plans or study misunderstood diseases, like Alzheimer's disease, both in humans and in small animal models of these diseases. The accuracy of the exam depends on the expert's training, but also on the quality of the images in terms of resolution (how small can we see) and contrast (sharp difference between dark and bright areas). The technology of current PET scanners has reached the limit in terms of resolution, so research to boost image quality has turned towards improving the contrast. This can be done through a complementary measurement mode named time-of-flight (ToF). In this mode, the detection of the radioactive molecule, mentioned above, becomes much more accurate, and this accuracy translates into a better contrast as there is less `guesswork' involved during the generation of the image. My research program's overall goal is to design, build and test a PET detector system that will measure ToF with 10 picosecond accuracy, which corresponds to 10 millionth of one millionth of a second. With radiation moving at the speed of light, this corresponds to a 1.5 mm spatial accuracy. For comparison, the best commercial clinical scanners have a TOF accuracy of about 400 picosecond, or 6 cm. A massively multidisciplinary goal, my research program leverages recent innovations achieved at Université de Sherbrooke in ultra-fast sensor electronics. To achieve the 10 picosecond detector, my program will contribute to 1) experimentally confirm that liquid xenon, a very fast detection material but seldom used in PET, can reach the 10 picosecond goal or not; 2) develop electronics that can handle networks of these new sensors and process their gigabits per second of generated data on the fly, otherwise unmanageable in the clinic 3) investigate the compatibility of emerging low-cost sensors with PET for eventual commercialization of the scanner system. The resulting detector module will enable the construction of a new generation of high contrast human PET scanners, with more than 10x improvement over the best commercial scanners in the world. This increased contrast will allow us to inject less radioactive molecules in patients when performing PET scans, hence opening PET imaging to pediatric, natal and neonatal imaging. Lastly, my cutting-edge program will consolidate Canada's position as world leader in state-of-the-art PET scanner design.