The present disclosure relates to a positron emission tomography detector and a positron emission tomography system using the same. More particularly, the positron emission tomography detector includes: a lower detecting unit configured to have a plurality of detector modules disposed in a ring or polygonal shape and an upper detecting unit configured to have a plurality of detector modules which are spaced apart from each other by a predetermined distance, or of which at least some are in contact with each other to be formed on the lower detecting unit, and formed in a conical shape which is tilted by a preset angle. By the configuration as described above, since the positron emission tomography detector and the positron emission tomography system using the same according to the present disclosure have a large number of effective lines of response (LOR) and increase geometric efficiency, it is possible to improve sensitivity.
