Dynamic tracking of moving targets

Abstract

Treatment targets such as tumors or lesions, located within an anatomical region that undergoes motion (which may be periodic with cycle P), are dynamically tracked. A 4D mathematical model is established for the non-rigid motion and deformation of the anatomical region, from a set of CT or other 3D images. The 4D mathematical model relates the 3D locations of part(s) of the anatomical region with the targets being tracked, as a function of the position in time within P. Using fiducial-less non-rigid image registration between pre-operative DRRs and intra-operative x-ray images, the absolute position of the target and/or other part(s) of the anatomical region is determined. The cycle P is determined using motion sensors such as surface markers. The radiation beams are delivered using: 1) the results of non-rigid image registration; 2) the 4D model; and 3) the position in time within P.

1 . A method, comprising:
 developing a four-dimensional model to describe a movement of a target region over time; and   developing a radiation treatment plan based on the four-dimensional model, wherein developing the radiation treatment plan comprises determining a relative movement between a radiation beam path and the target region.   
     
     
         2 . The method of  claim 1 , wherein developing the radiation treatment plan further comprises determining a gating of a radiation beam, based on the relative movement, to intersect the target region with the radiation beam path. 
     
     
         3 . The method of  claim 2 , wherein determining the gating of the radiation beam comprises determining a duration to turn on the radiation beam when intersecting with the target region to give a desired dose distribution of the radiation treatment plan.