skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: WE-H-BRC-08: Examining Credentialing Criteria and Poor Performance Indicators for IROC Houston’s Anthropomorphic Head and Neck Phantom

Abstract

Purpose: To analyze the most recent results of IROC Houston’s anthropomorphic H&N phantom to determine the nature of failing irradiations and the feasibility of altering pass/fail credentialing criteria. Methods: IROC Houston’s H&N phantom, used for IMRT credentialing for NCI-sponsored clinical trials, requires that an institution’s treatment plan must agree with measurement within 7% (TLD doses) and ≥85% pixels must pass 7%/4 mm gamma analysis. 156 phantom irradiations (November 2014 – October 2015) were re-evaluated using tighter criteria: 1) 5% TLD and 5%/4 mm, 2) 5% TLD and 5%/3 mm, 3) 4% TLD and 4%/4 mm, and 4) 3% TLD and 3%/3 mm. Failure/poor performance rates were evaluated with respect to individual film and TLD performance by location in the phantom. Overall poor phantom results were characterized qualitatively as systematic (dosimetric) errors, setup errors/positional shifts, global but non-systematic errors, and errors affecting only a local region. Results: The pass rate for these phantoms using current criteria is 90%. Substituting criteria 1-4 reduces the overall pass rate to 77%, 70%, 63%, and 37%, respectively. Statistical analyses indicated the probability of noise-induced TLD failure at the 5% criterion was <0.5%. Using criteria 1, TLD results were most often the cause of failure (86%more » failed TLD while 61% failed film), with most failures identified in the primary PTV (77% cases). Other criteria posed similar results. Irradiations that failed from film only were overwhelmingly associated with phantom shifts/setup errors (≥80% cases). Results failing criteria 1 were primarily diagnosed as systematic: 58% of cases. 11% were setup/positioning errors, 8% were global non-systematic errors, and 22% were local errors. Conclusion: This study demonstrates that 5% TLD and 5%/4 mm gamma criteria may be both practically and theoretically achievable. Further work is necessary to diagnose and resolve dosimetric inaccuracy in these trials, particularly for systematic dose errors. This work is funded by NCI Grant CA180803.« less

Authors:
; ; ; ;  [1]
  1. UT MD Anderson Cancer Center, Houston, TX (United States)
Publication Date:
OSTI Identifier:
22617040
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 43; Journal Issue: 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; CLINICAL TRIALS; DIAGNOSIS; ERRORS; FAILURES; HEAD; NECK; PERFORMANCE; PHANTOMS; POSITIONING; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Carson, M, Molineu, A, Taylor, P, Followill, D, and Kry, S. WE-H-BRC-08: Examining Credentialing Criteria and Poor Performance Indicators for IROC Houston’s Anthropomorphic Head and Neck Phantom. United States: N. p., 2016. Web. doi:10.1118/1.4957986.
Carson, M, Molineu, A, Taylor, P, Followill, D, & Kry, S. WE-H-BRC-08: Examining Credentialing Criteria and Poor Performance Indicators for IROC Houston’s Anthropomorphic Head and Neck Phantom. United States. doi:10.1118/1.4957986.
Carson, M, Molineu, A, Taylor, P, Followill, D, and Kry, S. Wed . "WE-H-BRC-08: Examining Credentialing Criteria and Poor Performance Indicators for IROC Houston’s Anthropomorphic Head and Neck Phantom". United States. doi:10.1118/1.4957986.
@article{osti_22617040,
title = {WE-H-BRC-08: Examining Credentialing Criteria and Poor Performance Indicators for IROC Houston’s Anthropomorphic Head and Neck Phantom},
author = {Carson, M and Molineu, A and Taylor, P and Followill, D and Kry, S},
abstractNote = {Purpose: To analyze the most recent results of IROC Houston’s anthropomorphic H&N phantom to determine the nature of failing irradiations and the feasibility of altering pass/fail credentialing criteria. Methods: IROC Houston’s H&N phantom, used for IMRT credentialing for NCI-sponsored clinical trials, requires that an institution’s treatment plan must agree with measurement within 7% (TLD doses) and ≥85% pixels must pass 7%/4 mm gamma analysis. 156 phantom irradiations (November 2014 – October 2015) were re-evaluated using tighter criteria: 1) 5% TLD and 5%/4 mm, 2) 5% TLD and 5%/3 mm, 3) 4% TLD and 4%/4 mm, and 4) 3% TLD and 3%/3 mm. Failure/poor performance rates were evaluated with respect to individual film and TLD performance by location in the phantom. Overall poor phantom results were characterized qualitatively as systematic (dosimetric) errors, setup errors/positional shifts, global but non-systematic errors, and errors affecting only a local region. Results: The pass rate for these phantoms using current criteria is 90%. Substituting criteria 1-4 reduces the overall pass rate to 77%, 70%, 63%, and 37%, respectively. Statistical analyses indicated the probability of noise-induced TLD failure at the 5% criterion was <0.5%. Using criteria 1, TLD results were most often the cause of failure (86% failed TLD while 61% failed film), with most failures identified in the primary PTV (77% cases). Other criteria posed similar results. Irradiations that failed from film only were overwhelmingly associated with phantom shifts/setup errors (≥80% cases). Results failing criteria 1 were primarily diagnosed as systematic: 58% of cases. 11% were setup/positioning errors, 8% were global non-systematic errors, and 22% were local errors. Conclusion: This study demonstrates that 5% TLD and 5%/4 mm gamma criteria may be both practically and theoretically achievable. Further work is necessary to diagnose and resolve dosimetric inaccuracy in these trials, particularly for systematic dose errors. This work is funded by NCI Grant CA180803.},
doi = {10.1118/1.4957986},
journal = {Medical Physics},
number = 6,
volume = 43,
place = {United States},
year = {Wed Jun 15 00:00:00 EDT 2016},
month = {Wed Jun 15 00:00:00 EDT 2016}
}