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Title: SU-E-T-316: The Design of a Risk Index Method for 3D Patient Specific QA

Abstract

Purpose: To suggest a new guidance for the evaluation of 3D patient specific QA, a structure-specific risk-index (RI) method was designed and implemented. Methods: A new algorithm was designed to assign the score of Pass, Fail or Pass with Risk to all 3D voxels in each structure by improving a conventional Gamma Index (GI) algorithm, which implied the degree of the risk of under-dose to the treatment target or over-dose to the organ at risks (OAR). Structure-specific distance to agreement (DTOA), dose difference and minimum checkable dose were applied to the GI algorithm, and additional parameters such as dose gradient factor and dose limit of structures were used to the RI method. Maximum passing rate (PR) and minimum PR were designed and calculated for each structure with the RI method. 3D doses were acquired from a spine SBRT plan by simulating the shift of beam iso-center, and tested to show the feasibility of the suggested method. Results: When the iso-center was shifted by 1 mm, 2 mm, and 3 mm, the PR of conventional GI method between shifted and non-shifted 3D doses were 99.9%, 97.4%, and 89.7% for PTV, 99.8%, 84.8%, and 63.2% for spinal cord, and 100%, 99.5%, 91.7%more » for right lung. The minimum PRs from the RI method were 98.9%, 96.9%, and 89.5% for PTV, and 96.1%, 79.3%, 57.5% for spinal cord, and 92.5%, 92.0%, 84.4% for right lung, respectively. The maximum PRs from the RI method were equal or less than the PRs from the conventional GI evaluation. Conclusion: Designed 3D RI method showed more strict acceptance level than the conventional GI method, especially for OARs. The RI method is expected to give the degrees of risks in the delivered doses, as well as the degrees of agreements between calculated 3D doses and measured (or simulated) 3D doses.« less

Authors:
;  [1];  [2];  [3]
  1. Seoul National University Hospital, Seoul (Korea, Republic of)
  2. Stanford University, Stanford, CA (United States)
  3. Catholic UniversityMedical College, Seoul (Korea, Republic of)
Publication Date:
OSTI Identifier:
22355872
Resource Type:
Journal Article
Journal Name:
Medical Physics
Additional Journal Information:
Journal Volume: 41; Journal Issue: 6; Other Information: (c) 2014 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-2405
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ALGORITHMS; DOSE LIMITS; HEALTH HAZARDS; LUNGS; PATIENTS; RADIATION DOSES; SPINAL CORD; VERTEBRAE

Citation Formats

Cho, W, Wu, H, Xing, L, and Suh, T. SU-E-T-316: The Design of a Risk Index Method for 3D Patient Specific QA. United States: N. p., 2014. Web. doi:10.1118/1.4888649.
Cho, W, Wu, H, Xing, L, & Suh, T. SU-E-T-316: The Design of a Risk Index Method for 3D Patient Specific QA. United States. https://doi.org/10.1118/1.4888649
Cho, W, Wu, H, Xing, L, and Suh, T. 2014. "SU-E-T-316: The Design of a Risk Index Method for 3D Patient Specific QA". United States. https://doi.org/10.1118/1.4888649.
@article{osti_22355872,
title = {SU-E-T-316: The Design of a Risk Index Method for 3D Patient Specific QA},
author = {Cho, W and Wu, H and Xing, L and Suh, T},
abstractNote = {Purpose: To suggest a new guidance for the evaluation of 3D patient specific QA, a structure-specific risk-index (RI) method was designed and implemented. Methods: A new algorithm was designed to assign the score of Pass, Fail or Pass with Risk to all 3D voxels in each structure by improving a conventional Gamma Index (GI) algorithm, which implied the degree of the risk of under-dose to the treatment target or over-dose to the organ at risks (OAR). Structure-specific distance to agreement (DTOA), dose difference and minimum checkable dose were applied to the GI algorithm, and additional parameters such as dose gradient factor and dose limit of structures were used to the RI method. Maximum passing rate (PR) and minimum PR were designed and calculated for each structure with the RI method. 3D doses were acquired from a spine SBRT plan by simulating the shift of beam iso-center, and tested to show the feasibility of the suggested method. Results: When the iso-center was shifted by 1 mm, 2 mm, and 3 mm, the PR of conventional GI method between shifted and non-shifted 3D doses were 99.9%, 97.4%, and 89.7% for PTV, 99.8%, 84.8%, and 63.2% for spinal cord, and 100%, 99.5%, 91.7% for right lung. The minimum PRs from the RI method were 98.9%, 96.9%, and 89.5% for PTV, and 96.1%, 79.3%, 57.5% for spinal cord, and 92.5%, 92.0%, 84.4% for right lung, respectively. The maximum PRs from the RI method were equal or less than the PRs from the conventional GI evaluation. Conclusion: Designed 3D RI method showed more strict acceptance level than the conventional GI method, especially for OARs. The RI method is expected to give the degrees of risks in the delivered doses, as well as the degrees of agreements between calculated 3D doses and measured (or simulated) 3D doses.},
doi = {10.1118/1.4888649},
url = {https://www.osti.gov/biblio/22355872}, journal = {Medical Physics},
issn = {0094-2405},
number = 6,
volume = 41,
place = {United States},
year = {Sun Jun 01 00:00:00 EDT 2014},
month = {Sun Jun 01 00:00:00 EDT 2014}
}