Characterisation of fluorescence imaging and silicon photomultiplier based gamma camera A

Abstract

To date, surgery is the most common method to treat cancer. Complete tumour resection, however, can be challenging as it relies on the surgeon’s ability to visually discriminate healthy from diseased tissues. Additional contrast mechanisms are needed to further guide cancer identification during surgery. Small field of view (SFOV) gamma imaging has been widely introduced for image-guided cancer surgery. A novel SFOV hybrid gamma camera (HGC) has been developed, at the University of Leicester, that is capable of providing coaligned images from optical and gamma modalities simultaneously. The HGC has the potential to enhance tumour localisation intraoperatively. In this thesis, a dedicated near infrared fluorescence imaging (NIRFI) systems have been characterised for combination with the HGC. The performance of two NIRF imaging systems using phantom studies, various fluorophores and different experimental configurations was evaluated. Bespoke lymph node phantoms simulating metastases and tissue-like layers were constructed to evaluate the detection capability. The threshold detectable concentration of both dyes were investigated for both systems. The maximum depth at which NIRF targets could be distinguished was determined for both systems. Silicon photomultiplier (SiPM) is a novel photon sensing device, with potential applications in medical gamma imaging. This thesis also characterised different parameters of the SiPM under different operating conditions. Better knowledge of the SiPM technology was obtained to exploit its advantages in an introperative SFOV gamma imaging system. This work also reported the performance of gamma detectors comprising SiPM detector optically coupled to a monolithic GAGG:Ce and a columnar CsI:TI scintillators. A thin layer of both scintillators was investigated in order to determine their performance features such as linearity, intrinsic energy resolution and detection efficiency when combined to a SiPM.