How many small crystals typically make up a PET detector block?

A typical PET detector block is composed of a large number of small crystals, which are essential for detecting the gamma rays produced during positron-electron annihilation events. These crystals are usually made from materials such as bismuth germanate (BGO) or lutetium oxyorthosilicate (LSO), capable of converting the gamma radiation into visible light, which is then read by photodetectors.

The range of 10,000 to 35,000 small crystals found in a detector block is supported by the requirement for high spatial resolution and sensitivity in PET imaging. A higher number of smaller crystals allows for better detection of the emitted radiation, improving the overall image quality and allowing for better localization of the radio tracers within the body. This number strikes a balance between sufficient granularity for accurate spatial detection and the need to maintain an efficient, workable detector size.

Understanding the specifics of the number of crystals helps to clarify the technical design aspects of PET systems and their implications for image resolution and diagnostic efficacy.