An attenuation correction method and device for an image in a PET system. The method comprises: acquiring transmission scanning chordal graph data of a current PET device; reconstructing the transmission scanning chordal graph data by adopting a Bayesian model-based ordered subset expectation maximization (OSEM-B) method and a Filtered Back Projection (FBP) method to obtain an OSEM-B attenuation image and a first FBP attenuation image, respectively; weighting the OSEM-B attenuation image and the first FBP attenuation image to acquire an effective attenuation image; and performing attenuation correction on emission scanning chordal graph data of the current PET device by adopting an attenuation chordal graph generated based on the effective attenuation image. The method and device disclosed in the embodiments of the present invention are capable of making the quality of an attenuation image reach the quality precision of long-time transmission scanning, and at the same time reducing the time of transmission scanning.
ATTENUATION CORRECTION METHOD AND DEVICE FOR IMAGE IN PET SYSTEM