11.4 A 67,392-SPAD PVTB-compensated multi-channel digital SiPM with 432 column-parallel 48ps 17b TDCs for endoscopic time-of-flight PET

Positron emission tomography (PET) is a medical imaging technique for non-invasive detection of glucose metabolism in human organs, such as the brain, heart, and lungs. A positron-emitting molecule, generally Fluorodeoxyglucose-18 (¹⁸F-FDG), is injected and subsequently identified by coincident detection of two gamma photons released during the annihilation of an electron with the positron lost by ^1BF-FDG. Conventionally, coincident gamma photons are detected through scintillation by two sensors placed at 180° in a ring of identical sensors. In EndoTOFPET-US, two sensors are used, one placed in a semicircular ring outside the patient and the other placed on an endoscope. The endoscopic sensor is a miniaturized array of silicon photomultipliers (SiPMs) coupled to a mini-scintillator. To exploit the Fishburn-Seifert lower bound in timing resolution, a large number of photon timestamps must be generated, as is done in a multi-channel digital SiPM (MD-SiPM).