Premium
TH‐EF‐BRD‐04: A Fast 4D IMRT/VMAT Planning Method Based On Segment Aperture Morphing
Author(s) -
Klawikowski S,
Tai A,
Ates O,
Ahunbay E,
Li X
Publication year - 2015
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4926291
Subject(s) - isocenter , morphing , computer science , nuclear medicine , phase (matter) , aperture (computer memory) , radiation treatment planning , image registration , translation (biology) , image warping , plan (archaeology) , artificial intelligence , medical physics , computer vision , imaging phantom , medicine , physics , radiation therapy , image (mathematics) , radiology , geology , acoustics , biochemistry , chemistry , quantum mechanics , messenger rna , gene , paleontology
Purpose: To investigate dosimetric advantages of a 4D IMRT/VMAT planning method employing a segment aperture morphing (SAM) algorithm accounting for respiration‐induced target motion and deformation. The minimal required number of calculated SAM phases was tested to minimize plan creation time. Methods: The new technique involves generating 4D step‐and‐shoot IMRT or VMAT plans based on 10‐phase 4DCT in the following steps: (1) optimizing a flattening‐filter‐free IMRT/VMAT plan based on the 50% phase CT dataset (2) warping contours from the 50%‐phase CT to the remaining phases via deformable image registration (DIR) and manual editing (3) morphing segment apertures of the 50%‐phase plan to each phase CT using SAM that adjusts each aperture shape based on the change of the beam's‐eye‐view of the target contour between the two phases (4) calculating the dose distribution for each phase with the morphed apertures and same MUs as in the 50%‐phase plan, and (5) generating the 4D plan by accumulating the dose from all nine SAM‐corrected phases and the original 50% optimized phase using DIR. 4D plans based on 10, 7, 5 and 3 SAM‐corrected phases were generated for representative lung and pancreatic cancer cases, and were compared using DVH analysis against the gold‐standard 4D plan where all 10 phases are individually planned and optimized. A SAM‐corrected 4D plan was also compared to a simpler phase‐by‐phase isocenter‐shifted plan to assess accounting for tumor deformation and translation opposed to only tumor translation. Results: Plan DVH quality for the 10‐phase and 7‐phase 4D SAM plans were comparable with the fully‐optimized 4D plans (PTV‐D95's within 3% of fully‐optimized plans). SAM based algorithms out‐performed simpler isocenter‐shifted‐only approaches (∼1.5% PTV‐D95 improvement). SAM‐based 4D planning greatly reduces planning time verses individually optimized phase planning techniques. Conclusion: SAM with DIR provides a fast and accurate way to create 4D IMRT/VMAT plans.