Patent ID: 8238519

Claim:
A method comprising: determining that a motion of a patient area of a patient due to breathing is substantially periodic according to a treatment plan, wherein the treatment plan specifies a first treatment gantry angle at which a prescribed dose of radiation is to be delivered, a nominal time between consecutive breathes of the patient, and a gantry travel time during which a radiotherapy beam shaping device is configured for delivery of the prescribed dose of radiation and is equal to the nominal time between consecutive breathes of the patient; moving a radiotherapy gantry towards the first treatment gantry angle; moving the radiotherapy beam shaping device towards a first treatment shape corresponding to the first treatment gantry angle according to the treatment plan; determining when a next treatment window is to begin based on a predictive model derived from the motion of the patient area, the treatment window being a period of time designated for delivery of a treatment radiation beam to the patient area according to the treatment plan; adjusting the moving of the radiotherapy gantry such that the radiotherapy gantry will reach the first treatment angle during the determined next treatment window; and delivering a treatment radiation beam to the patient area during the determined next treatment window, wherein the radiotherapy gantry is at the first treatment gantry angle and the radiotherapy shaping device is configured to the first treatment shape.