The department of radiation oncology at Siteman Cancer Center has treated its 2,000th patient using the MRIdian, MRI-guided radiation therapy system by ViewRay. Patients treated at Siteman Cancer Center benefit from MRI on-table adaptive radiotherapy, real-time tissue tracking, and automated beam control which allows for delivering the prescribed dose to the target while sparing surrounding healthy tissue and critical structures, and results in minimizing toxicities. In January 2014, Siteman Cancer Center became the first in the world to treat patients using the MRI-guided radiation therapy system. Over the past nine years, the clinical team at Washington University has been a leader in publishing clinical evidence related to treating using the MRI-guided system. They were the first to publish prospective clinical trial data in MRI-guidance with pancreatic cancer and the first to publish prospective data on CT simulation-free MRI-guided treatment of palliative treatments. The department currently completes over 100 adaptive treatments per month.