Program Information
Improvement of Conformal Arc Plans By Using Deformable Margin DelineationTechnique in Stereotactic Body Radiotherapy
G GUNGOR*, M DEMIR , G AYDIN , B ATALAR , B YAPICI , E OZYAR , ACIBADEM UNIVERSITY, Istanbul, ISTANBUL
Presentations
SU-I-GPD-T-579 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: Stereotactic body radiotherapy(SBRT) is an established technique in early stage lung cancer. Both volumetric modulated arc(VMAT) and conformal arc(3DCA) techniques can be used as a treatment method.In this study, we aimed to analyze whether deformable margin delineation technique(DMD) improves the quality of the 3DCA technique and to compare it with VMAT plans.
Methods: Twenty stage I non-small cell lung cancer patients were included. VMAT and 3DCA non-coplanar plans were generated with 6MV FFF photons to conform planning target volume(PTV) according to RTOG 0915. As conventionally 3DCA plans have inferior target coverage compared to VMAT plans, we deformed PTV contour in order to get a better isodose coverage using DMD technique. All techniques were compared in terms of dosimetric parameters; Ratio of prescription isodose volume (IV) to PTV (conformity index-CI), ratio of 50% prescription IV to PTV(Intermediate dose spillage volume-IDSV), maximum dose in % of dose prescribed at 2cm from PTV(Intermediate dose spillage location-IDSL), and percentage of lung receiving 20Gy (V20) respectively.
Results: CI ranged between 1.00–1.17(Mean: 1.02); 1.00–1.25(Mean: 1.06); 1.04–1.29(Mean 1.15) for 3DCA-DMD-FFF, VMAT-FFF and 3DCA-FFF, respectively. 3DCA-DMD have significantly better CI compared to others (p
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