Dynamic sub-space intensity modulation

摘要

A system and method for dynamic subspace intensity modulation. Portions around the edges of a multi-leaf collimator-defined static radiation field are expanded or shrunk during part or all of the delivery of radiation at constant velocity. In order to match some or all of the sloping regions (502) of an intensity profile, the individual leaves (41, 42) of the multi-leaf collimator are moved at a fixed velocity over the sloping portions (502) of the intensity profile. By keeping the major portion of the field static and by only moving the leaves at one fixed velocity over a small subspace of the intensity profile, it is relatively easier to know what dose the patient receives and it is also relatively easier to resume treatment since it can be determined exactly how many more monitor units of radiation must be delivered and what the leaf positions were when the radiation was turned off. <IMAGE>