Patent ID: 7835493

Claim:
A method for four-dimensional (4D) intensity modulated radiation therapy (IMRT) planning for motion compensated treatments, comprising: creating a deliverable IMRT treatment plan for a tumor in irregular periodic motion, said irregular period of motion comprising a plurality of phases, said treatment plan comprising treatment plans for each of said plurality of phases, each said treatment plan being delivered using a multi-leaf collimator, leaf positions of said multi-leaf collimator being adapted separately for each respective phase and for each of a plurality of beam positions, the beam being collimated by said multi-leaf collimator, determining a gross tumor volume (GTV) centroid for each of said plurality of phases; designating one of said plurality of phases as a reference phase; and targeting said collimator for each phase by a displacement relative to the GTV centroid of the reference phase, wherein said phases are defined by dividing said irregular period into equal parts of time, wherein said adapted leaf positions are constant during each phase, and wherein a collimator angle for each said beam position is aligned to a major axis of motion of the GTV centroid over said plurality of phases as viewed by said beam (BEV).