A Position Emission Tomography (PET) system is provided in the present disclosure. According to an example, the PET system includes a detector and a host computer, where the detector includes: a plurality of detector rings; each of the detector rings including n number of collecting modules arranged in a circumferential direction of the detector ring, where n is an integer greater than 1; a first collecting module of the n number of collecting modules coupled with the host computer; an n-th collecting module of the n number of collecting module coupled with a (n−1)-th collecting module; and an i-th collecting module coupled with an (i−1)-th collecting module, where i is an integer greater than 1 and less than n.