Instrumentation and Data Acquisition

Abstract

Nuclear medical images are formed by the detection of gamma-rays, X-rays or annihilation quanta (in the case of positron imaging). The camera detects the density of gamma rays per unit area, their energy and their direction of flight. If single photon emitters are used the direction of flight has to be determined by geometric collimation. In contrast, coincidence detection uses the unique feature of positron annihilation which results in two high-energy gamma rays simultaneously emitted back-to-back. The detection of both gamma rays within a very short time window defines the line of response in space and thus the direction of flight. Scintigraphic instrumentation consists of scintillation crystals to convert gamma-ray energy into visible light, suitable light sensors, readout electronics and image processing units.