Masters of Science (Research)
School of Physics
Pinn, Christopher James, Characterisation of a dual detector probe for medical physics applications, Masters of Science (Research) thesis, School of Physics, University of Wollongong, 2014. http://ro.uow.edu.au/theses/4173
Non-invasive surgery is an increasing requirement in modern day surgical theatres. A patient’s recovery experience, and even their long term quality of life, can be affected by the amount of extensive invasion required in surgery. This issue is particularly prevalent in Cancer based surgical wards, where the removal of all cancer afflicted cells from a human body is critical to success. The difficulties associated with achieving this task are numerous: Identification of the correct cells for removal, removal of afflicted tissue that ensures complete cancer cell absence in the patient, non-excessive removal of tissue to improve the patient’s quality of life and recovery time after surgery.
In an attempt to address these problems, Lymphoscintigraphy was developed to locate afflicted cells prior to surgical removal. Lymphoscintigraphy provides the surgeon with a map illustrating the location of afflicted cells throughout a patients’ body. This allows the surgeon to plan the most minimally invasive procedure whilst still acquiring the maximum afflicted tissue possible. The timeframe between a Lymphoscintigraphic scan and surgery however means that cancer cells can develop and spread further throughout the patient’s body. In short, a more immediate time frame between detection and removal of cancer cells is required to ensure surgical success.
An intraoperative Lymphoscintigraphy device needs to be developed that caters for the needs of the Radio-guided surgical theatre, a fast radionuclide detection response time, highly accurate physical localisation of the emission source point, adjustable and Active Collimation to allow for wide to narrow detection windows in performing this localisation, the capacity to resolve the isotopes commonly preferred for implementation in the medical theatre.
CMRP has developed in the last decade an innovative solution to cope with the requirements of an intraoperative probe: the Liana Dual Detection Probe (DDP). The focus of this study is the characterisation of detectors with their related electronics for the purpose of further development to the DDP. Though Liana is intended as a medically based instrument, it is not limited to medically based functions. Liana’s wide to narrow digital Active Collimation will be explored using characterisation from a pure physics perspective. The results of the exploration are then addressed back to the requirements of the medical theatre.
Characterisation of the Liana probe provided significant physical insight into the fundamentals of detector operation. Characterisation of the probes energy and localisation resolution explored effects such as Compton induced Background Scattering events and Penumbra. IV (Current vs Voltage) and CV (Capacitance vs Voltage) characteristics of the photodiode investigated the dependence of the wavelength absorption region upon the impurities present within the diode. The impact of an electronics design change from a previous study by Bradley Franks was assessed to identify improvements in managing the physical phenomena occurring within the detector.
These unique facets illustrated how the design of a dual detector must account for the physical phenomena associated with the interactions of energy emissions with matter.