Characterization of a Single Pixel Beta Detector for Guidance in Breast-Conserving Surgery

Breast-conserving surgery (BCS) is a challenging surgical procedure due to the lack of intraoperative image guidance available to surgeons. One potential method of intra-operative guidance would be radio-guided surgery with adiopharmaceutical emitting beta particles. In this thesis, a single pixel beta sensitive detector was constructed and characterized for intra-operative guidance during BCS. The thickness of the scintillation element of the detector was optimized to obtain a superior beta to gamma detection ratio. A computer model of the detector response was derived from an empirically measured, two-dimensional (2D) detector response. An in silico study evaluated whether the novel single pixel beta detector could detect less than 1 mm² deposits of cancer at the cut edge of the surgically excised cancerous tissue, with a sensitivity and specificity of 95%. A thickness of 0.5 mm for a CaF₂(Eu) scintillator was found to be optimal for a beta to gamma detection ratio. Additionally, according to an in silico study it is expected that with an acquisition time of 30 seconds, a tumour-to-background ratio of 5 or higher, and a normal breast tissue activity of 1.69 kBq/ml, detection of cancerous deposits of less than 1 mm² is possible. The result of this thesis demonstrate that radio-guided BCS, with a CaF₂(Eu) scintillation beta particle detector, can intra-operatively assess the tumour margin involvement, which would help surgeons in determining resection margins.