Advances in Detector Instrumentation for PET

Abstract

During the last 3 decades, PET has become a standard-of-care imaging technique used in the management of cancer and in the characterization of neurologic disorders and cardiovascular disease. It has also emerged as a prominent molecular imaging method to study the basic biologic pathways of disease in rodent models. This review describes the basics of PET detectors, including a detailed description of indirect and direct 511-keV photon detection methods. We will also cover key detector performance parameters and describe detector instrumentation advances during the last decade.

Keywords: CTR; PET; coincidence time resolution; scintillation detectors; semiconductor detectors; spatial and energy resolution.

FIGURE 1.

Illustration of PET imaging process: from left to right, radiolabeled tracer is injected into patient body, then PET scan is performed, and finally acquired annihilation photon data are processed to reconstruct images. ADC = analog-to-digital converter; FPGA = field programmable gate array; TDC = time-to-digital converter.

FIGURE 2.

Schematic of PMT (A) and SiPM array (B), zooming on circuitry of one SiPM comprising 2-dimensional array of thousands of microcells. SPAD = single photon avalanche diode.

FIGURE 3.

Schematic of different scintillation crystal–photodetector coupling approaches. End readout configurations with one-to-one coupling (A), light sharing (B and C), one-to-one coupling but with SiPMs on entrance face (D), side readout (E), dual-ended readout (F), and lateral readout (G) (a more common configuration is depicted in Supplemental Fig. 1B).