Nearly two-thirds of all cancer patients in the U.S. receive radiation therapy to treat their illness. Many advanced technologies have been developed to create precise and optimized ionizing radiation treatments where patients are modeled as static objects. All current radiotherapy technology, however, has a major shortcoming: it cannot determine where the radiation is actually being delivered in a patient’s body while the treatment beam is on. This is because patients aren’t static objects; they’re people, and their bodies naturally and inherently move. This movement is often significant enough to cause the radiation to miss the intended target and unnecessarily irradiate healthy tissue, potentially leading to more side effects and fewer cures. We will discuss the technological development of a unique combination of magnetic resonance imaging (MRI) and external-beam radiation therapy delivery technology, named the ViewRayTM System. This system is being designed to provide pretreatment images and continuous soft-tissue imaging while the treatment beam is on allowing clinicians can clearly see the target and track movement to guide the delivery of the therapy.