A radiotherapy system comprising an X-ray tube operating at 100 to 800 kVp for providing X-ray beams of 50 mm diameter or less (and preferably approximately 30 mm or less) and configured to move the entrance beam footprint on the body during irradiation to any arbitrary sequential position set that has been predetermined to limit the intervening tissue dose rate at any one location to a safe level, such that the sum of the skin area traversed during treatment is 20 to 100 times the beam area.
