Development of a Radiation Counting System Based on a Plastic Scintillator for Medical Applications

Radiotracer input function study is a common method to study the physiological and biochemical processes in early drug development as well as for therapeutic purpose and it is usually clinically performed on small animals to reduce blood withdrawal that can cause blood depletion. It is crucial for testing devices for these studies to give accurate radioactivity detection measurements. The common measurement principle is also applied in quality control tests of radiotracer production to ensure accurate amount of dose being produced. It is desirable of such testing devices to handle low volumes of radioactive fluid. This research aimed to develop and study two types of miniaturised scintillation particle detectors. The first part of the thesis introduces a novel type of scintillator detector based on microfluidic technology. Such detector combines microfluidic technologies to radiation detection technologies that can be used widely in both fields. Microfluidic technology manipulates microvolume of fluids to manage its chemical and physical processes. It is cheaper to manufacture and can be made into various shapes and sizes. The proposed detector can measure radiotracer activity in fluid in a microfluidic channel that is used to determine the input function in real time. The second part of the thesis describes a detector based on scintillating fiber technology. The beta probe was fabricated using scintillating fiber and SiPM. It is the first attempt to utilize fiber scintillator for the full length of the detector. Due to the size, flexibility and cost of manufacturing of such fiber, it is the best possible option for activity counting in narrow diameter environment such as blood vessels. It is especially beneficial for input function study in the small animal study where blood drawing method is not preferred.