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Title: Choreographing Couch and Collimator in Volumetric Modulated Arc Therapy

Abstract

Purpose: To design and optimize trajectory-based, noncoplanar subarcs for volumetric modulated arc therapy (VMAT) deliverable on both Varian TrueBEAM system and traditional accelerators; and to investigate their potential advantages for treating central nervous system (CNS) tumors. Methods and Materials: To guide the computerized selection of beam trajectories consisting of simultaneous couch, gantry, and collimator motion, a score function was implemented to estimate the geometric overlap between targets and organs at risk for each couch/gantry angle combination. An initial set of beam orientations is obtained as a function of couch and gantry angle, according to a minimum search of the score function excluding zones of collision. This set is grouped into multiple continuous and extended subarcs subject to mechanical limitations using a hierarchical clustering algorithm. After determination of couch/gantry trajectories, a principal component analysis finds the collimator angle at each beam orientation that minimizes residual target-organ at risk overlaps. An in-house VMAT optimization algorithm determines the optimal multileaf collimator position and monitor units for control points within each subarc. A retrospective study of 10 CNS patients compares the proposed method of VMAT trajectory with dynamic gantry, leaves, couch, and collimator motion (Tra-VMAT); a standard noncoplanar VMAT with no couch/collimator motion withinmore » subarcs (Std-VMAT); and noncoplanar intensity-modulated radiotherapy (IMRT) plans that were clinically used. Results: Tra-VMAT provided improved target dose conformality and lowered maximum dose to brainstem, optic nerves, and chiasm by 7.7%, 1.1%, 2.3%, and 1.7%, respectively, compared with Std-VMAT. Tra-VMAT provided higher planning target volume minimum dose and reduced maximum dose to chiasm, optic nerves, and cochlea by 6.2%, 1.3%, 6.3%, and 8.4%, respectively, and reduced cochlea mean dose by 8.7%, compared with IMRT. Tra-VMAT averaged beam-on time was comparable to Std-VMAT but significantly (45%) less than IMRT. Conclusion: Optimized couch, gantry, and collimator trajectories may be integrated into VMAT with improved mechanical flexibility and may provide better dosimetric properties and improved efficiency in the treatment of CNS tumors.« less

Authors:
 [1];  [1]; ; ; ;  [1];  [2]; ;  [1]
  1. Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
  2. Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
Publication Date:
OSTI Identifier:
21587612
Resource Type:
Journal Article
Journal Name:
International Journal of Radiation Oncology, Biology and Physics
Additional Journal Information:
Journal Volume: 80; Journal Issue: 4; Other Information: DOI: 10.1016/j.ijrobp.2010.10.016; PII: S0360-3016(10)03435-8; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0360-3016
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ALGORITHMS; CENTRAL NERVOUS SYSTEM; COLLIMATORS; HAZARDS; NEOPLASMS; NERVES; ORGANS; RADIATION DOSES; RADIOTHERAPY; TRAJECTORIES; BODY; DISEASES; DOSES; MATHEMATICAL LOGIC; MEDICINE; NERVOUS SYSTEM; NUCLEAR MEDICINE; RADIOLOGY; THERAPY

Citation Formats

Yang Yingli, Zhang Pengpeng, E-mail: zhangp@mskcc.org, Happersett, Laura, Xiong Jianping, Yang Jie, Chan, Maria, Beal, Kathryn, Mageras, Gig, and Hunt, Margie. Choreographing Couch and Collimator in Volumetric Modulated Arc Therapy. United States: N. p., 2011. Web. doi:10.1016/j.ijrobp.2010.10.016.
Yang Yingli, Zhang Pengpeng, E-mail: zhangp@mskcc.org, Happersett, Laura, Xiong Jianping, Yang Jie, Chan, Maria, Beal, Kathryn, Mageras, Gig, & Hunt, Margie. Choreographing Couch and Collimator in Volumetric Modulated Arc Therapy. United States. doi:10.1016/j.ijrobp.2010.10.016.
Yang Yingli, Zhang Pengpeng, E-mail: zhangp@mskcc.org, Happersett, Laura, Xiong Jianping, Yang Jie, Chan, Maria, Beal, Kathryn, Mageras, Gig, and Hunt, Margie. Fri . "Choreographing Couch and Collimator in Volumetric Modulated Arc Therapy". United States. doi:10.1016/j.ijrobp.2010.10.016.
@article{osti_21587612,
title = {Choreographing Couch and Collimator in Volumetric Modulated Arc Therapy},
author = {Yang Yingli and Zhang Pengpeng, E-mail: zhangp@mskcc.org and Happersett, Laura and Xiong Jianping and Yang Jie and Chan, Maria and Beal, Kathryn and Mageras, Gig and Hunt, Margie},
abstractNote = {Purpose: To design and optimize trajectory-based, noncoplanar subarcs for volumetric modulated arc therapy (VMAT) deliverable on both Varian TrueBEAM system and traditional accelerators; and to investigate their potential advantages for treating central nervous system (CNS) tumors. Methods and Materials: To guide the computerized selection of beam trajectories consisting of simultaneous couch, gantry, and collimator motion, a score function was implemented to estimate the geometric overlap between targets and organs at risk for each couch/gantry angle combination. An initial set of beam orientations is obtained as a function of couch and gantry angle, according to a minimum search of the score function excluding zones of collision. This set is grouped into multiple continuous and extended subarcs subject to mechanical limitations using a hierarchical clustering algorithm. After determination of couch/gantry trajectories, a principal component analysis finds the collimator angle at each beam orientation that minimizes residual target-organ at risk overlaps. An in-house VMAT optimization algorithm determines the optimal multileaf collimator position and monitor units for control points within each subarc. A retrospective study of 10 CNS patients compares the proposed method of VMAT trajectory with dynamic gantry, leaves, couch, and collimator motion (Tra-VMAT); a standard noncoplanar VMAT with no couch/collimator motion within subarcs (Std-VMAT); and noncoplanar intensity-modulated radiotherapy (IMRT) plans that were clinically used. Results: Tra-VMAT provided improved target dose conformality and lowered maximum dose to brainstem, optic nerves, and chiasm by 7.7%, 1.1%, 2.3%, and 1.7%, respectively, compared with Std-VMAT. Tra-VMAT provided higher planning target volume minimum dose and reduced maximum dose to chiasm, optic nerves, and cochlea by 6.2%, 1.3%, 6.3%, and 8.4%, respectively, and reduced cochlea mean dose by 8.7%, compared with IMRT. Tra-VMAT averaged beam-on time was comparable to Std-VMAT but significantly (45%) less than IMRT. Conclusion: Optimized couch, gantry, and collimator trajectories may be integrated into VMAT with improved mechanical flexibility and may provide better dosimetric properties and improved efficiency in the treatment of CNS tumors.},
doi = {10.1016/j.ijrobp.2010.10.016},
journal = {International Journal of Radiation Oncology, Biology and Physics},
issn = {0360-3016},
number = 4,
volume = 80,
place = {United States},
year = {2011},
month = {7}
}