PHASER builds on the innovative RF linac and power source developments from our high-energy technology group. Using the first fundamental technological advances in nearly 60 years, since the first medical linac in the Western Hemisphere was used to cure a young patient with cancer at Stanford University, we are redefining how radiation medicine is practiced. We move past the outdated assumptions that 3D imaging, radiation treatment and conformal dose delivery are fundamentally slow compared to physiologic motion. We will instead deliver therapy using an ultrafast treatment paradigm, freezing motion rather than tracking it. This paradigm shift creates unprecedented possibilities for globally accessible, cost-effective, precision radiotherapy with new indications for cancer and other major illnesses, personalization of multi-modality treatment with targeted radiotherapy and targeted molecular agents, and exploitation of novel radiobiological mechanisms in tumors and normal tissues.