Document Detail

Effects of respiratory motion on passively scattered proton therapy versus intensity modulated photon therapy for stage III lung cancer: are proton plans more sensitive to breathing motion?
MedLine Citation:
PMID:  24074932     Owner:  NLM     Status:  MEDLINE    
PURPOSE: To quantify and compare the effects of respiratory motion on paired passively scattered proton therapy (PSPT) and intensity modulated photon therapy (IMRT) plans; and to establish the relationship between the magnitude of tumor motion and the respiratory-induced dose difference for both modalities.
METHODS AND MATERIALS: In a randomized clinical trial comparing PSPT and IMRT, radiation therapy plans have been designed according to common planning protocols. Four-dimensional (4D) dose was computed for PSPT and IMRT plans for a patient cohort with respiratory motion ranging from 3 to 17 mm. Image registration and dose accumulation were performed using grayscale-based deformable image registration algorithms. The dose-volume histogram (DVH) differences (4D-3D [3D = 3-dimensional]) were compared for PSPT and IMRT. Changes in 4D-3D dose were correlated to the magnitude of tumor respiratory motion.
RESULTS: The average 4D-3D dose to 95% of the internal target volume was close to zero, with 19 of 20 patients within 1% of prescribed dose for both modalities. The mean 4D-3D between the 2 modalities was not statistically significant (P<.05) for all dose-volume histogram indices (mean ± SD) except the lung V5 (PSPT: +1.1% ± 0.9%; IMRT: +0.4% ± 1.2%) and maximum cord dose (PSPT: +1.5 ± 2.9 Gy; IMRT: 0.0 ± 0.2 Gy). Changes in 4D-3D dose were correlated to tumor motion for only 2 indices: dose to 95% planning target volume, and heterogeneity index.
CONCLUSIONS: With our current margin formalisms, target coverage was maintained in the presence of respiratory motion up to 17 mm for both PSPT and IMRT. Only 2 of 11 4D-3D indices (lung V5 and spinal cord maximum) were statistically distinguishable between PSPT and IMRT, contrary to the notion that proton therapy will be more susceptible to respiratory motion. Because of the lack of strong correlations with 4D-3D dose differences in PSPT and IMRT, the extent of tumor motion was not an adequate predictor of potential dosimetric error caused by breathing motion.
Jason Matney; Peter C Park; Jaques Bluett; Yi Pei Chen; Wei Liu; Laurence E Court; Zhongxing Liao; Heng Li; Radhe Mohan
Publication Detail:
Type:  Comparative Study; Journal Article; Randomized Controlled Trial; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  International journal of radiation oncology, biology, physics     Volume:  87     ISSN:  1879-355X     ISO Abbreviation:  Int. J. Radiat. Oncol. Biol. Phys.     Publication Date:  2013 Nov 
Date Detail:
Created Date:  2013-09-30     Completed Date:  2013-11-18     Revised Date:  2014-11-04    
Medline Journal Info:
Nlm Unique ID:  7603616     Medline TA:  Int J Radiat Oncol Biol Phys     Country:  United States    
Other Details:
Languages:  eng     Pagination:  576-82     Citation Subset:  IM    
Copyright Information:
Copyright © 2013 Elsevier Inc. All rights reserved.
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MeSH Terms
Aged, 80 and over
Carcinoma, Non-Small-Cell Lung / pathology,  radiography,  radiotherapy*
Four-Dimensional Computed Tomography
Lung Neoplasms / pathology,  radiography,  radiotherapy*
Middle Aged
Photons / therapeutic use
Proton Therapy / methods*
Radiotherapy Dosage
Radiotherapy Planning, Computer-Assisted / methods*
Radiotherapy, Intensity-Modulated / methods*
Tumor Burden
Young Adult
Grant Support
K25 CA168984/CA/NCI NIH HHS; P01 CA021239/CA/NCI NIH HHS; P01CA021239/CA/NCI NIH HHS; P30 CA016672/CA/NCI NIH HHS

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