Prospective Data Registry and Quality of Life Assessment of Patients Undergoing Radiotherapy With the RefleXion Medical Radiotherapy System

This multi-center prospective registry is designed to assess the efficacy of IMRT, SBRT, and BgRT delivered via the RMRS. The study will seek to enroll approximately 750 patients initially and then remain open to further patients beyond at the discretion of the study sponsor and participating institutions. The number of IMRT, SBRT, and BgRT patients expected to enroll for the initial period is as follows: * N = 250 IMRT * N - 250 SBRT * N - 250 BgRT Patients diagnosed with local, locoregionally advanced, or metastatic malignancies will be treated with IMRT, SBRT, or BgRT using the RMRS, with total dose, fractionation, and concurrent systemic therapy delivered according to the direction of the radiation oncology care team. The target population is patients for whom standard radiotherapy is prescribed using IMRT, SBRT, and BgRT. Data will be stratified by common radiotherapy divisions as follows: * Central Nervous System (Brain, spinal cord, and vertebral column) * Head and Neck * Thoracic * Gastrointestinal * Gynecologic * Genitourinary * Lymphoma * Melanoma/Sarcoma/Extremity * Non-Spine Bone and Other An additional sub-stratum within each anatomic division will specify whether the treatment intent is for definitive treatment of the primary tumor (for early-stage or locally advanced disease), a definitive oligo/polymetastatic therapy, or a palliative therapy. Patients will be routinely assessed during their radiation course and thereafter for toxicity burden and HRQOL using the CTCAE v5, EORTC, and EuroQOL surveys. Patients will be assessed for 2 years following their therapy. Other long-term follow-ups will capture data including standard of care (per physician's discretion) laboratory evaluation, quality of life questionnaires, performance status, routine radiographic assessments, physical exams, etc. (see Appendix B. Schedule of Events).