What role do PMTs play in PET imaging?

In positron emission tomography (PET) imaging, photomultiplier tubes (PMTs) play a critical role in the detection process. When positrons emitted from the radiotracer interact with electrons in the body, they annihilate, producing pairs of gamma photons that travel in opposite directions. These photons then pass through the scintillation crystals, which convert the gamma photon energy into visible light.

The PMTs are responsible for detecting this visible light generated by the scintillation crystals. They convert the light into an electrical signal, which is then processed to help form the image. The sensitivity and efficiency of PMTs make them essential for accurately capturing the signals that lead to high-quality imaging.

Other options do not accurately describe the function of PMTs. They do not generate annihilation photons; these are produced during the annihilation event itself. PMTs are not involved in calibrating the field of view (FOV) or providing power supply; these functions are handled by different components within the imaging system. Thus, the role of PMTs as signal detectors is fundamental to the overall PET imaging process.