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SU‐E‐T‐890: Comparison of SBRT Lung Treatments Using 3D Conformal, Conformal Arcs and VMAT
Author(s) -
Haslam J,
Paul T
Publication year - 2011
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 - 10.1118/1.3612854
Subject(s) - conformal map , medicine , radiation treatment planning , nuclear medicine , pinnacle , linear particle accelerator , medical physics , radiation therapy , physics , radiology , mathematics , beam (structure) , optics , geometry
Purpose: Stereotactic Body Radiotherapy (SBRT) treatments for lung tumors were originally delivered using multiple (>10) non‐coplanar 3D conformal beams. This technique produces very conformal dose distributions that minimize the amount of normal lung irradiated. The disadvantage of this treatment technique is the extended treatment delivery time, usually between 30 to 45 minutes, due to the numerous beams and couch angles. These prolonged treatments times can be prohibitive in busy departments where machine time is limited, or where certain patients, especially elderly patients, have a hard time remaining still for extended periods of time. The aim of this study is to show that lung SBRT treatment plans created using VMAT and conformal arc treatment plans are dosimetrically equivalent to 3D conformal plans. Methods: This is a retrospective study of 5 patients treated in our clinic. All plans will be created using Pinnacle version 9.0 (Phillips Radiation Oncology Systems, Fitchburg, WI) and delivered using and Elekta Synergy S linear accelerator (Elekta, Inc., Peachtree, GA). All patients were treated to to 50 Gy in 5 fractions, and all plans used the conformality criteria from RTOG 0236 as goals. Results: 3D conformal treatment plans were planned with 10 beams, including 6 couch angles, while VMAT and conformal arc plans were used 2 arcs. All plans easily meet the R100 criteria, while no planning method is able to meet the strict R50 criteria. However, the R50 was lower for the 3D conformal plan. Additionally, the V20 volumes were satisfactory for all plans. Treatment delivery times were reduced by a factor of 5 for VMAT plans and a factor of 3–4 for conformal arc plans. Conclusions: All SBRT treatments are treated using VMAT because the advantage of significantly reduced treatment times outweighs any slight dosimetric disadvantages. Funding provided by Elekta, Inc.