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Title: SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing

Abstract

Purpose: We propose a novel dosimetric audit method for clinical trials using EPID measurements at each center and a standardized EPID to dose conversion algorithm. The aim of this work is to investigate the applicability of the EPID method to different linear accelerator, EPID and treatment planning system (TPS) combinations. Methods: Combination of delivery and planning systems were three Varian linacs including one Pinnacle and two Eclipse TPS and, two ELEKTA linacs including one Pinnacle and one Monaco TPS. All Varian linacs had the same EPID structure and similarly for the ELEKTA linacs. Initially, dose response of the EPIDs was investigated by acquiring integrated pixel value (IPV) of the central area of 10 cm2 images versus MUs, 5-400 MU. Then, the EPID to dose conversion was investigated for different system combinations. Square field size images, 2, 3, 4, 6, 10, 15, 20, 25 cm2 acquired by all systems were converted to dose at isocenter of a virtual flat phantom then the dose was compared to the corresponding TPS dose. Results: All EPIDs showed a relatively linear behavior versus MU except at low MUs which showed irregularities probably due to initial inaccuracies of irradiation. Furthermore, for all the EPID models, themore » model predicted TPS dose with a mean dose difference percentage of 1.3. However the model showed a few inaccuracies for ELEKTA EPID images at field sizes larger than 20 cm2. Conclusion: The EPIDs demonstrated similar behavior versus MU and the model was relatively accurate for all the systems. Therefore, the model could be employed as a global dosimetric method to audit clinical trials. Funding has been provided from Department of Radiation Oncology, TROG Cancer Research and the University of Newcastle. Narges Miri is a recipient of a University of Newcastle postgraduate scholarship.« less

Authors:
 [1];  [2];  [3];  [2];  [4]
  1. University of Newcastle, Newcastle, NSW (Australia)
  2. Calvary Mater Newcastle, Newcastle, NSW (Australia)
  3. Liverpool Hospital, Sydney, NSW (Australia)
  4. (Australia)
Publication Date:
OSTI Identifier:
22648856
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:
62 RADIOLOGY AND NUCLEAR MEDICINE; 43 PARTICLE ACCELERATORS; 60 APPLIED LIFE SCIENCES; CLINICAL TRIALS; DOSIMETRY; EDUCATIONAL FACILITIES; IMAGES; LINEAR ACCELERATORS; QUALITY ASSURANCE

Citation Formats

Miri, N, Lehmann, J, Vial, P, Greer, P, and University of Newcastle, Newcastle, NSW. SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing. United States: N. p., 2016. Web. doi:10.1118/1.4956380.
Miri, N, Lehmann, J, Vial, P, Greer, P, & University of Newcastle, Newcastle, NSW. SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing. United States. doi:10.1118/1.4956380.
Miri, N, Lehmann, J, Vial, P, Greer, P, and University of Newcastle, Newcastle, NSW. Wed . "SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing". United States. doi:10.1118/1.4956380.
@article{osti_22648856,
title = {SU-F-T-240: EPID-Based Quality Assurance for Dosimetric Credentialing},
author = {Miri, N and Lehmann, J and Vial, P and Greer, P and University of Newcastle, Newcastle, NSW},
abstractNote = {Purpose: We propose a novel dosimetric audit method for clinical trials using EPID measurements at each center and a standardized EPID to dose conversion algorithm. The aim of this work is to investigate the applicability of the EPID method to different linear accelerator, EPID and treatment planning system (TPS) combinations. Methods: Combination of delivery and planning systems were three Varian linacs including one Pinnacle and two Eclipse TPS and, two ELEKTA linacs including one Pinnacle and one Monaco TPS. All Varian linacs had the same EPID structure and similarly for the ELEKTA linacs. Initially, dose response of the EPIDs was investigated by acquiring integrated pixel value (IPV) of the central area of 10 cm2 images versus MUs, 5-400 MU. Then, the EPID to dose conversion was investigated for different system combinations. Square field size images, 2, 3, 4, 6, 10, 15, 20, 25 cm2 acquired by all systems were converted to dose at isocenter of a virtual flat phantom then the dose was compared to the corresponding TPS dose. Results: All EPIDs showed a relatively linear behavior versus MU except at low MUs which showed irregularities probably due to initial inaccuracies of irradiation. Furthermore, for all the EPID models, the model predicted TPS dose with a mean dose difference percentage of 1.3. However the model showed a few inaccuracies for ELEKTA EPID images at field sizes larger than 20 cm2. Conclusion: The EPIDs demonstrated similar behavior versus MU and the model was relatively accurate for all the systems. Therefore, the model could be employed as a global dosimetric method to audit clinical trials. Funding has been provided from Department of Radiation Oncology, TROG Cancer Research and the University of Newcastle. Narges Miri is a recipient of a University of Newcastle postgraduate scholarship.},
doi = {10.1118/1.4956380},
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}
}