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Title: Institutional Patient-specific IMRT QA Does Not Predict Unacceptable Plan Delivery

Purpose: To determine whether in-house patient-specific intensity modulated radiation therapy quality assurance (IMRT QA) results predict Imaging and Radiation Oncology Core (IROC)-Houston phantom results. Methods and Materials: IROC Houston's IMRT head and neck phantoms have been irradiated by numerous institutions as part of clinical trial credentialing. We retrospectively compared these phantom results with those of in-house IMRT QA (following the institution's clinical process) for 855 irradiations performed between 2003 and 2013. The sensitivity and specificity of IMRT QA to detect unacceptable or acceptable plans were determined relative to the IROC Houston phantom results. Additional analyses evaluated specific IMRT QA dosimeters and analysis methods. Results: IMRT QA universally showed poor sensitivity relative to the head and neck phantom, that is, poor ability to predict a failing IROC Houston phantom result. Depending on how the IMRT QA results were interpreted, overall sensitivity ranged from 2% to 18%. For different IMRT QA methods, sensitivity ranged from 3% to 54%. Although the observed sensitivity was particularly poor at clinical thresholds (eg 3% dose difference or 90% of pixels passing gamma), receiver operator characteristic analysis indicated that no threshold showed good sensitivity and specificity for the devices evaluated. Conclusions: IMRT QA is not a reasonablemore » replacement for a credentialing phantom. Moreover, the particularly poor agreement between IMRT QA and the IROC Houston phantoms highlights surprising inconsistency in the QA process.« less
Authors:
 [1] ;  [1] ; ; ; ; ;  [1] ;  [2] ;  [1] ;  [3] ;  [2] ;  [1] ;  [2]
  1. Imaging and Radiation Oncology Core at Houston, Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas (United States)
  2. (United States)
  3. The University of Texas Health Science Center Houston, Graduate School of Biomedical Sciences, Houston, Texas (United States)
Publication Date:
OSTI Identifier:
22420513
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 90; Journal Issue: 5; 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; BIOMEDICAL RADIOGRAPHY; CLINICAL TRIALS; COMPARATIVE EVALUATIONS; DOSEMETERS; HEAD; NECK; PATIENTS; PHANTOMS; QUALITY ASSURANCE; RADIOTHERAPY; SPECIFICITY