A number of clinical trials have shown the efficacy of stereotactic body radiosurgery (SBRT), for treatment of lung, liver and other cancers. Lung SBRT, for example, achieved 96.7% of local tumor control rate. However, toxicity is significant. An effective use of emerging 4D PET image information in treatment planning provides a significant opportunity to reduce the tumor margin and radiation side effects while maintaining the excellent tumor local control rate of the treatment. We report a 4D PET image reconstruction method to solve the unmet problem of temporo-spatio resolution competition in 4D PET imaging and describe a method of integrating the 4D PET data into respiration-gated SBRT planning. During the processes of forward- and backward-projection in the ML-EM iterations, all projection data acquired at different phases are combined together to update the emission map with the aid of deformable model, the statistics is therefore greatly improved. Liver, lung and pancreatic patients were acquired via the gated PET mode. A single-bed FOV PET scan typically requires several minutes to acquire adequate data for reconstruction, necessarily spanning several respiratory cycles and smearing the radiotracer signal within a given lesion over an increased volume. Although prospective or retrospective gating captures the PET image at a single point in the respiratory cycle, restricting the data to events within the gating interval increases the SNR. We developed a 4D Pet reconstruction method to combine the data from the entire respiratory cycle through deformable registration. The exhale or inhale phase was selected as the gating phase for SBRT planning. The residual motion inside a selected gating widow is considered by measuring the motion range in the 4D PET images. A gated IMRT inverse planning was then carried out with 4D PET defined tumortarget. We found that the performance of 4D PET was significantly improved by the proposed reconstruction with the SNR increased by ~6 folds over conventional PET. Using 4D PET, 35%~48% reduction in target volumes was observed, which leads to significant reduction in radiation toxicity and makes it possible for patients to truly benefit from the modern SBRT treatment.