Evaluating Radionuclide Detection Technologies: A Study of Stationary TGS and Dynamic 3D Gamma Imaging Systems in Radiological Characterisation

Radiological characterisation plays a crucial role in nuclear engineering, providing essential tools for the accurate assessment and management of radioactive materials across diverse sectors, including nuclear decommissioning and CBRN (Chemical, Biological, Radiological, and Nuclear) threat mitigation. Innovations are underway to enable specialists to operate safely from a distance. This thesis conducts a comparative analysis of radionuclide detection and imaging technologies, focusing on two distinct systems. The first is the Tomographic Gamma Scanner (TGS), a stationary device that utilizes a High-Purity Germanium (HPGe) detector for 3D analysis of object matrix density and radionuclide activity. The second is a portable gamma-ray imaging spectrometer, equipped with a Cadmium Zinc Telluride (CZT) detector. On its own, this detector performs 2D Gamma Imaging reconstructions, employing both Compton Imaging and Coded Aperture Imaging techniques along with an optical camera. When integrated with the SLAM-based imaging system GammAware, it further provides 3D Gamma Imaging capabilities, significantly enhancing its functional scope The primary goal of this research is to assess the imaging and reconstruction capabilities of the stationary TGS setup versus the dynamic, portable system. For this comparison, sources of cesium, americium, and cobalt were placed within a common reference structure to evaluate the quality of the reconstructions. This involves a thorough comparison of outputs from both systems, focusing particularly on the detailed reconstructions provided by the portable system, especially when augmented by the GammAware for 3D point cloud generation of scenes and sources. These reconstructions are carefully analysed, offering a novel comparison of environmental reconstructions achieved through LIDAR, utilised by GammAware, and photogrammetry, which provides a more realistic colour representation of the scene. The findings from this analysis hightlight the significant capabilities and some limitations of the two technologies, suggesting areas for future development to enhance their application in radiological assessments.