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Title: The Effect of Contouring Variability on Dosimetric Parameters for Brain Metastases Treated With Stereotactic Radiosurgery

Purpose: To quantify the effect of contouring variation on stereotactic radiosurgery plan quality metrics for brain metastases. Methods and Materials: Fourteen metastases, each contoured by 8 physicians, formed the basis of this study. A template-based dynamic conformal 5-arc dose distribution was developed for each of the 112 contours, and each dose distribution was applied to the 7 other contours in each patient set. Radiation Therapy Oncology Group (RTOG) plan quality metrics and the Paddick conformity index were calculated for each of the 896 combinations of dose distributions and contours. Results: The ratio of largest to smallest contour volume for each metastasis varied from 1.25 to 4.47, with a median value of 1.68 (n=8). The median absolute difference in RTOG conformity index between the value for the reference contour and the values for the alternative contours was 0.35. The variation of the range of conformity index for all contours for a given tumor varied with the tumor size. Conclusions: The high degree of interobserver contouring variation strongly suggests that peer review or consultation should be adopted to standardize tumor volume prescription. Observer confidence was not reflected in contouring consistency. The impact of contouring variability on plan quality metrics, used as criteriamore » for clinical trial protocol compliance, was such that the category of compliance was robust to interobserver effects only 70% of the time.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ; ; ;  [2] ;  [3] ; ;  [2] ;  [1]
  1. Department of Medical Physics, Tom Baker Cancer Center, Calgary, Alberta (Canada)
  2. Department of Radiation Oncology, Tom Baker Cancer Center, Calgary, Alberta (Canada)
  3. Department of Neuroradiology, University of Calgary, Calgary, Alberta (Canada)
Publication Date:
OSTI Identifier:
22278271
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 87; Journal Issue: 5; Other Information: Copyright (c) 2013 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; BRAIN; CLINICAL TRIALS; METASTASES; NEOPLASMS; RADIATION DOSE DISTRIBUTIONS; RADIOTHERAPY; SURGERY