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Dose Constraints In Imrt
1. The Use of Equivalent Uniform Dose constraints in IMRT Thomas Bortfeld 1 , Christian Thieke 1,2 , Yair Censor 3 1 Department of Radiation Oncology, Massachusetts General Hospital, Boston, USA 2 Department of Medical Physics, Deutsches Krebsforschungszentrum, Heidelberg, Germany, 3 Department of Mathematics, University of Haifa, Israel
4. "Positivity projector": penalty (weight) dose at voxel i in OAR k tolerance dose Penalty function: Constraints: Maximum (tolerance) doses "The spinal cord should get less than 40 Gy."
5. Small penalty ( w ) Volume Dose d max Large penalty ( w ) DVH Volume d max Dose DVH
13. Constraints: Dose-volume constraints "No more than 1/3 of the lung should get more than 15 Gy."
14. Why are DVH constraints non-convex? Critical structure consisting of 2 voxels d 1 d 2 Not more than 50% of the volume (1 voxel) should get more than 30 Gy 30 Gy 30 Gy feasible region d 1 d 2
35. Initialization Organ Constraint d pres ({organ}) = ... d pres ({organ}) = ... d pres ({organ}) = ... all organs processed? Adjoint dose calculation Dose calculation Calc. objective function converged ? End Max/min DVH EUD no yes no yes