A Prospective Study of Performing MRI Simulation in Treatment Position in Spinal Stereotactic Body Radiation Therapy

1\. Objectives 1. Assess the feasibility of performing MRI scans in the treatment position for accurate treatment planning and dose delivery in spinal stereotactic body radiation therapy (spinal SBRT). 2. Characterize the improved accuracy of image fusion between MRI and CT and its dosimetric impact when performing MRI scans in treatment position in spinal SBRT. 3. Assess the ability of MRI simulation to accurately target extended spinal targets beyond the current targeting limitations (\>3 consecutive vertebral body levels) 4. Optimize the workflow of using MRI simulation in treatment planning and dose delivery.