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SU‐GG‐J‐14: A Novel Integrated Approach for Individualizing Beam Directions and Motion Management
Author(s) -
Miften M,
Reitz B,
Gayou O,
Parda D
Publication year - 2008
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 - 10.1118/1.2961571
Subject(s) - fluoroscopy , radiation treatment planning , nuclear medicine , motion (physics) , beam (structure) , projection (relational algebra) , computer science , radiation therapy , computer vision , artificial intelligence , optics , physics , medicine , radiology , algorithm
Purpose: To develop an integrated technique to individualize treatment planning (TP) and management of inter‐ and intra‐fraction motion for NSCLC patients treated with 3DCRT or SBRT. Method and Materials: The technique involves first using MV‐CBCT in a cine mode prior to planning for optimal beam angle selection and verification of ITV and PTV 4DCT planning‐based margins. The angles are selected based on optimal geometrical tumor mass separation with respect to the surrounding OARs and optimal viewing of tumor motion in longitudinal (superior‐inferior/SI), vertical (anterior‐posterior/AP), and lateral (left‐right/LR) directions. Secondly, MV‐CBCT is used for daily tumor volume localization just prior to treatment. Thirdly, the EPID is deployed during treatment delivery to verify tumor motion and margins by capturing 7 frames per sec over 30 sec. Since the beam angles were selected to optimally view the target motion, the clinical benefits of using MV‐fluoroscopy (MV‐fluoro) to monitor tumor motion are maximized. To improve the contrast‐to‐noise ratio on the CB projection data and MV‐fluoro image frames, post‐processing with filtering techniques was used. Volumes of interest from the planning 4DCT were projected onto the MV‐cine and MV‐fluoro. Results: Data show optimal planning beam angles that ensured highly conformal dose distributions and viewing tumor motion in SI, AP, and LR directions derived from the cine data were feasible. The patient tumor volume was localized with MV‐CBCT, which represents an average static volumetric image of the patient over 60 sec. The MV‐fluoro data confirmed the tumor mass was located within the PTV during treatment despite respiratory motion. Conclusion: Individualizing margins using 4DCT, deriving optimal beam angles based on quasi 3D motion data from MV‐cine, localizing with CB, and verifying tumor motion and margins with MV‐fluoro is a clinically viable integrated technique, allowing for inter‐ and intra‐fraction motion management.