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Title: Clinical Implementation of Intensity Modulated Proton Therapy for Thoracic Malignancies

Purpose: Intensity modulated proton therapy (IMPT) can improve dose conformality and better spare normal tissue over passive scattering techniques, but range uncertainties complicate its use, particularly for moving targets. We report our early experience with IMPT for thoracic malignancies in terms of motion analysis and management, plan optimization and robustness, and quality assurance. Methods and Materials: Thirty-four consecutive patients with lung/mediastinal cancers received IMPT to a median 66 Gy(relative biological equivalence [RBE]). All patients were able to undergo definitive radiation therapy. IMPT was used when the treating physician judged that IMPT conferred a dosimetric advantage; all patients had minimal tumor motion (<5 mm) and underwent individualized tumor-motion dose-uncertainty analysis and 4-dimensional (4D) computed tomographic (CT)-based treatment simulation and motion analysis. Plan robustness was optimized by using a worst-case scenario method. All patients had 4D CT repeated simulation during treatment. Results: IMPT produced lower mean lung dose (MLD), lung V{sub 5} and V{sub 20}, heart V{sub 40}, and esophageal V{sub 60} than did IMRT (P<.05) and lower MLD, lung V{sub 20}, and esophageal V{sub 60} than did passive scattering proton therapy (PSPT) (P<.05). D{sub 5} to the gross tumor volume and clinical target volume was higher with IMPT than with intensity modulated radiationmore » therapy or PSPT (P<.05). All cases were analyzed for beam-angle-specific motion, water-equivalent thickness, and robustness. Beam angles were chosen to minimize the effect of respiratory motion and avoid previously treated regions, and the maximum deviation from the nominal dose-volume histogram values was kept at <5% for the target dose and met the normal tissue constraints under a worst-case scenario. Patient-specific quality assurance measurements showed that a median 99% (range, 95% to 100%) of the pixels met the 3% dose/3 mm distance criteria for the γ index. Adaptive replanning was used for 9 patients (26.5%). Conclusions: IMPT using 4D CT-based planning, motion management, and optimization was implemented successfully and met our quality assurance parameters for treating challenging thoracic cancers.« less
Authors:
 [1] ; ;  [2] ; ;  [1] ;  [2] ;  [2] ;  [3] ; ;  [2] ;  [1] ; ;  [2] ;  [2]
  1. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
  2. Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22420468
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 90; Journal Issue: 4; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; COMPUTERIZED TOMOGRAPHY; ESOPHAGUS; HEART; LUNGS; NEOPLASMS; OPTIMIZATION; PATIENTS; PLANNING; PROTON BEAMS; QUALITY ASSURANCE; RADIATION DOSES; RADIOTHERAPY; RBE; SCATTERING