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Title: SU-E-T-69: Cloud-Based Monte Carlo Patient-Specific Quality Assurance (QA) Method for Volumetric Modulated Arc Therapy (VMAT)

Abstract

Purpose: Patient-specific QA for VMAT is incapable of providing full 3D dosimetric information and is labor intensive in the case of severe heterogeneities or small-aperture beams. A cloud-based Monte Carlo dose reconstruction method described here can perform the evaluation in entire 3D space and rapidly reveal the source of discrepancies between measured and planned dose. Methods: This QA technique consists of two integral parts: measurement using a phantom containing array of dosimeters, and a cloud-based voxel Monte Carlo algorithm (cVMC). After a VMAT plan was approved by a physician, a dose verification plan was created and delivered to the phantom using our Varian Trilogy or TrueBeam system. Actual delivery parameters (i.e., dose fraction, gantry angle, and MLC at control points) were extracted from Dynalog or trajectory files. Based on the delivery parameters, the 3D dose distribution in the phantom containing detector were recomputed using Eclipse dose calculation algorithms (AAA and AXB) and cVMC. Comparison and Gamma analysis is then conducted to evaluate the agreement between measured, recomputed, and planned dose distributions. To test the robustness of this method, we examined several representative VMAT treatments. Results: (1) The accuracy of cVMC dose calculation was validated via comparative studies. For cases thatmore » succeeded the patient specific QAs using commercial dosimetry systems such as Delta- 4, MAPCheck, and PTW Seven29 array, agreement between cVMC-recomputed, Eclipse-planned and measured doses was obtained with >90% of the points satisfying the 3%-and-3mm gamma index criteria. (2) The cVMC method incorporating Dynalog files was effective to reveal the root causes of the dosimetric discrepancies between Eclipse-planned and measured doses and provide a basis for solutions. Conclusion: The proposed method offers a highly robust and streamlined patient specific QA tool and provides a feasible solution for the rapidly increasing use of VMAT treatments in the clinic.« less

Authors:
; ; ;  [1];  [2]
  1. Stanford University, Palo Alto, CA (United States)
  2. Clinica Universidad de Navarra, Pamplona (Spain)
Publication Date:
OSTI Identifier:
22339836
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; ACCURACY; ALGORITHMS; DOSEMETERS; MONTE CARLO METHOD; PATIENTS; PHANTOMS; QUALITY ASSURANCE; RADIATION DOSE DISTRIBUTIONS; RADIATION DOSES; RADIOTHERAPY

Citation Formats

Chen, X, Xing, L, Luxton, G, Bush, K, and Azcona, J. SU-E-T-69: Cloud-Based Monte Carlo Patient-Specific Quality Assurance (QA) Method for Volumetric Modulated Arc Therapy (VMAT). United States: N. p., 2014. Web. doi:10.1118/1.4888399.
Chen, X, Xing, L, Luxton, G, Bush, K, & Azcona, J. SU-E-T-69: Cloud-Based Monte Carlo Patient-Specific Quality Assurance (QA) Method for Volumetric Modulated Arc Therapy (VMAT). United States. https://doi.org/10.1118/1.4888399
Chen, X, Xing, L, Luxton, G, Bush, K, and Azcona, J. 2014. "SU-E-T-69: Cloud-Based Monte Carlo Patient-Specific Quality Assurance (QA) Method for Volumetric Modulated Arc Therapy (VMAT)". United States. https://doi.org/10.1118/1.4888399.
@article{osti_22339836,
title = {SU-E-T-69: Cloud-Based Monte Carlo Patient-Specific Quality Assurance (QA) Method for Volumetric Modulated Arc Therapy (VMAT)},
author = {Chen, X and Xing, L and Luxton, G and Bush, K and Azcona, J},
abstractNote = {Purpose: Patient-specific QA for VMAT is incapable of providing full 3D dosimetric information and is labor intensive in the case of severe heterogeneities or small-aperture beams. A cloud-based Monte Carlo dose reconstruction method described here can perform the evaluation in entire 3D space and rapidly reveal the source of discrepancies between measured and planned dose. Methods: This QA technique consists of two integral parts: measurement using a phantom containing array of dosimeters, and a cloud-based voxel Monte Carlo algorithm (cVMC). After a VMAT plan was approved by a physician, a dose verification plan was created and delivered to the phantom using our Varian Trilogy or TrueBeam system. Actual delivery parameters (i.e., dose fraction, gantry angle, and MLC at control points) were extracted from Dynalog or trajectory files. Based on the delivery parameters, the 3D dose distribution in the phantom containing detector were recomputed using Eclipse dose calculation algorithms (AAA and AXB) and cVMC. Comparison and Gamma analysis is then conducted to evaluate the agreement between measured, recomputed, and planned dose distributions. To test the robustness of this method, we examined several representative VMAT treatments. Results: (1) The accuracy of cVMC dose calculation was validated via comparative studies. For cases that succeeded the patient specific QAs using commercial dosimetry systems such as Delta- 4, MAPCheck, and PTW Seven29 array, agreement between cVMC-recomputed, Eclipse-planned and measured doses was obtained with >90% of the points satisfying the 3%-and-3mm gamma index criteria. (2) The cVMC method incorporating Dynalog files was effective to reveal the root causes of the dosimetric discrepancies between Eclipse-planned and measured doses and provide a basis for solutions. Conclusion: The proposed method offers a highly robust and streamlined patient specific QA tool and provides a feasible solution for the rapidly increasing use of VMAT treatments in the clinic.},
doi = {10.1118/1.4888399},
url = {https://www.osti.gov/biblio/22339836}, 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}
}