Information that describes a target inside a patient to be treated with radiation is accessed from computer system memory. An arrangement of spots inside the target is determined. Each the spots corresponds to a location inside the target where a respective beam of radiation is to be directed during radiation treatment of the patient. A dose rate for each of the beams is determined. The dose rate for each beam is a dose delivered in less than one second to a spot corresponding to that beam. For example, each beam can deliver at least four grays (GY) in less than one second, and may deliver as much as 20 Gy to 50 Gy or 100 Gy or more in less than one second. A radiation treatment plan, that includes the arrangement of the spots and the dose rate for each of the beams, is stored in computer system memory.