Positron emission tomography systems

A PET system, comprising:

• multiple detector rings, each of the multiple detector rings including a plurality of detector modules and having an axial index respectively;
• at least one data processing card communicatively connected to the multiple detector rings, wherein the data processing card is configured to receive detection data with different axial indexes from the multiple detector rings, and determine a target event based on the detection data;
• and
• at least one coincidence event card configured to determine a coincidence event pair by processing the target event, wherein the coincidence event pair at least includes coincidence events detected by the multiple detector rings.

A PET system, comprising:

• multiple detector rings, each of the multiple detector rings including a plurality of detector modules, wherein the multiple detector rings are arranged side by side along an axial direction of the PET system to form an accommodation cavity;
• and
• a processing card communicatively connected to the multiple detector rings, and configured to:
• receive detection data from the multiple detector rings;
• determine a target event based on a target single event, detected by detector modules at a same circumferential position across the multiple detector rings;
• and
• determine a coincidence event pair by processing the target event.