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Title: Comparison of Radiation-Induced Normal Lung Tissue Density Changes for Patients From Multiple Institutions Receiving Conventional or Hypofractionated Treatments

Purpose: To quantitatively assess changes in computed tomography (CT)–defined normal lung tissue density after conventional and hypofractionated radiation therapy (RT). Methods and Materials: The pre-RT and post-RT CT scans from 118 and 111 patients receiving conventional and hypofractionated RT, respectively, at 3 institutions were registered to each other and to the 3-dimensional dose distribution to quantify dose-dependent changes in normal lung tissue density. Dose-response curves (DRC) for groups of patients receiving conventional and hypofractionated RT were generated for each institution, and the frequency of density changes >80 Hounsfield Units (HU) was modeled depending on the fractionation type using a Probit model for different follow-up times. Results: For the pooled data from all institutions, there were significant differences in the DRC between the conventional and hypofractionated groups; the respective doses resulting in 50% complication risk (TD{sub 50}) were 62 Gy (95% confidence interval [CI] 57-67) versus 36 Gy (CI 33-39) at <6 months, 48 Gy (CI 46-51) versus 31 Gy (CI 28-33) at 6-12 months, and 47 Gy (CI 45-49) versus 35 Gy (32-37) at >12 months. The corresponding m values (slope of the DRC) were 0.52 (CI 0.46-0.59) versus 0.31 (CI 0.28-0.34) at <6 months, 0.46 (CI 0.42-0.51) versus 0.30 (CI 0.26-0.34) at 6-12 months, and 0.45 (CI 0.42-0.50) versus 0.31more » (CI 0.27-0.35) at >12 months (P<.05 for all comparisons). Conclusion: Compared with conventional fractionation, hypofractionation has a lower TD{sub 50} and m value, both suggesting an increased degree of normal tissue density sensitivity with hypofractionation.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [2] ;  [1] ;  [5]
  1. Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado (United States)
  2. Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina (United States)
  3. Division of Biostatistics and Bioinformatics, University of Maryland Greenbaum Cancer Center, and Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland (United States)
  4. Department of Radiation Oncology, VU University Medical Center, Amsterdam (Netherlands)
  5. London Regional Cancer Program, London, Ontario (Canada)
Publication Date:
OSTI Identifier:
22420349
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 89; Journal Issue: 3; 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; CAT SCANNING; COMPARATIVE EVALUATIONS; FRACTIONATED IRRADIATION; HAZARDS; LUNGS; PATIENTS; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY