In this Physics Oncology Scan, we address the latest hot topic, flash radiation therapy. Although no human has been treated to date, investigators are strongly engaged. The available techniques range from x-rays to protons, with dose rates exceeding 10,000 Gy/s. An abundance of investigators and commercial entities are simultaneously studying the technical capabilities and biological impact. Thus far, the normal tissue sparing that has been evidenced in animal studies generates hope that this will translate into humans.