Technical and clinical experience with spine radiosurgery: a new technology for management of localized spine metastases

This study is to demonstrate the technical and clinical experience of applying image guided spinal radiosurgery for treatment of localized spinal metastasis. A dedicated shaped beam radiosurgery unit with intensity modulated radiotherapy (IMRT) and x-ray based image-guided radiotherapy (IGRT) were used for the radiosurgery procedure. A total of 196 patients with 270 lesions of spinal metastases were treated with this procedure from May 2001 to October 2005. All patients received single dose radiosurgery to the involved spine only. The radiosurgery dose was escalated from 10 to 18 Gy in 2 Gy increments. The technical experience using IMRT planning and IGRT implementation has been summarized. Clinical results reporting pain relief responses have been analyzed for the first 49 patients treated with this procedure. For IMRT treatment planning, seven posterior/oblique fields were generally used for spinal radiosurgery as the optimal setup to balance conformality versus complexity. A criterion of 10 Gy to 10% of the adjacent spinal cord volume has been met with satisfactory target dose coverage for most of the cases. When the spinal cord dose exceeded this constraint, the tumor coverage was somewhat compromised. Accurate target localization has been achieved for all patients using the x-ray image-guided system. The preliminary clinical results have demonstrated that pain response was achieved in 85% of patients, with neurological improvement in patients with spinal cord compression. Patients tolerated the treatment well without major acute toxicities. Image guided spinal radiosurgery can be successfully applied to treat patients with focal spine metastases.