Objective(s): Extensive studies have demonstrated the superior dosimetric advantages of cobalt-60 beams for stereotactic radiosurgery/body radiotherapy (SRS/SBRT) of intra- and extracranial tumors compared to higher energy x-rays due to the sharper beam penumbra and the use of non-coplanar multiple source arrangement. This work investigates the potential clinical benefits of a novel rotating Gamma ray system for SRS/SBRT. Methods: The new Gamma ray treatment system (CybeRay, OUR United RT Group, Xian, China) has a ring gantry and a focusing treatment head consisting of 16 cobalt-60 sources. Each source has 7 collimators of 6, 9, 12, 16, 20, 25 and 35mm diameter. The treatment head can swing 35° superiorly, allowing a total of 43° non-coplanar beam incident. The treatment couch provides 6-degrees-of-freedom motion compensation and the kV cone-beam CT system has a spatial resolution of 0.4mm. Monte Carlo simulations were performed to compute plan dose distributions and to compare with previously treated CyberKnife plans. Results: The CybeRay system had a 0.5mm isocenter accuracy. The lowdose acquisition mode of the CBCT system provided real-time fluoroscopy and 3D imaging at a dose level of <1cGy. The maximum dose rate was >3Gy/min at the center of a 16cm diameter PMMA spherical phantom. The output factor varied from 1 to 0.739 for intracranial treatment using 20mm to 6mm collimators, and from 1 to 0.698 for extracranial SRS/SBRT using all 7 collimators. The beam penumbra (20%/80%) was 3.3mm and 4.5mm for the 6mm and 35mm collimators. Superior treatment plans were obtained with CybeRay for intracranial tumor ablation with much reduced near target brain doses. CybeRay also produced favorable dose distributions for peripheral lung tumors using a partial-arc technique to spare the opposite lung and critical structures. Conclusions: The unique dosimetric properties of cobalt beams and the accurate stereotaxy/dose delivery make the new cobalt design an ideal system for advanced SRS/SBRT of intra- and extracranial targets.