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Title: SU-F-T-467: A Cross-Checking Approach for Dosimetric Verification of Beam- Matched Elekta Linear Accelerators

Abstract

Purpose: To verify the similarity of the dosimetric characteristics between two Elekta linear accelerators (linacs) in order to treat patients interchangeably on these two machines without re-planning. Methods: To investigate the viability of matching the 6 MV flattened beam on an existing linac (Elekta Synergy with Agility head) with a recently installed new linca (Elekta Versa HD), percent depth doses (PDD), flatness and symmetry output factors were compared for both machines. To validate the beam matching among machines, we carried out two approaches to cross-check the dosimetrical equivalence: 1) the prior treatment plans were re-computed based on the newly built Versa HD treatment planning system (TPS) model without changing the beam control points; 2) The same plans were delivered on both machines and the radiation dose measurements on a MapCheck2 were compared with TPS calculations. Three VMAT plans (Head and neck, lung, and prostate) were used in the study. Results: The difference between the PDDs for 10×10 cm{sup 2} field at all depths was less than 0.8%. The difference of flatness and symmetry for 30×30 cm{sup 2} field was less than 0.8%, and the measured output factors varies by less than 1% for each field size ranging from 2×2 cm2more » to 40×40 cm{sup 2}. For the same plans, the maximum difference of the two calculated dose distributions is 2% of prescription. For the QA measurements, the gamma index passing rates were above 99% for 3%/3mm criteria with 10% threshold for all three clinical plans. Conclusion: A beam modality matching between two Elekta linacs is demonstrated with a cross-checking approach.« less

Authors:
; ; ; ; ; ;  [1]
  1. University Hospitals Case Medical Center, Dept of Radiation Oncology, Cleveland, OH (United States)
Publication Date:
OSTI Identifier:
22649057
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; 61 RADIATION PROTECTION AND DOSIMETRY; 43 PARTICLE ACCELERATORS; BEAMS; DEPTH DOSE DISTRIBUTIONS; HEAD; LINEAR ACCELERATORS; PLANNING; RADIATION DOSES

Citation Formats

Zheng, Y, Yuan, J, Geis, P, Colussi, V, Machtay, M, Ellis, R, and Wessels, B. SU-F-T-467: A Cross-Checking Approach for Dosimetric Verification of Beam- Matched Elekta Linear Accelerators. United States: N. p., 2016. Web. doi:10.1118/1.4956652.
Zheng, Y, Yuan, J, Geis, P, Colussi, V, Machtay, M, Ellis, R, & Wessels, B. SU-F-T-467: A Cross-Checking Approach for Dosimetric Verification of Beam- Matched Elekta Linear Accelerators. United States. doi:10.1118/1.4956652.
Zheng, Y, Yuan, J, Geis, P, Colussi, V, Machtay, M, Ellis, R, and Wessels, B. Wed . "SU-F-T-467: A Cross-Checking Approach for Dosimetric Verification of Beam- Matched Elekta Linear Accelerators". United States. doi:10.1118/1.4956652.
@article{osti_22649057,
title = {SU-F-T-467: A Cross-Checking Approach for Dosimetric Verification of Beam- Matched Elekta Linear Accelerators},
author = {Zheng, Y and Yuan, J and Geis, P and Colussi, V and Machtay, M and Ellis, R and Wessels, B},
abstractNote = {Purpose: To verify the similarity of the dosimetric characteristics between two Elekta linear accelerators (linacs) in order to treat patients interchangeably on these two machines without re-planning. Methods: To investigate the viability of matching the 6 MV flattened beam on an existing linac (Elekta Synergy with Agility head) with a recently installed new linca (Elekta Versa HD), percent depth doses (PDD), flatness and symmetry output factors were compared for both machines. To validate the beam matching among machines, we carried out two approaches to cross-check the dosimetrical equivalence: 1) the prior treatment plans were re-computed based on the newly built Versa HD treatment planning system (TPS) model without changing the beam control points; 2) The same plans were delivered on both machines and the radiation dose measurements on a MapCheck2 were compared with TPS calculations. Three VMAT plans (Head and neck, lung, and prostate) were used in the study. Results: The difference between the PDDs for 10×10 cm{sup 2} field at all depths was less than 0.8%. The difference of flatness and symmetry for 30×30 cm{sup 2} field was less than 0.8%, and the measured output factors varies by less than 1% for each field size ranging from 2×2 cm2 to 40×40 cm{sup 2}. For the same plans, the maximum difference of the two calculated dose distributions is 2% of prescription. For the QA measurements, the gamma index passing rates were above 99% for 3%/3mm criteria with 10% threshold for all three clinical plans. Conclusion: A beam modality matching between two Elekta linacs is demonstrated with a cross-checking approach.},
doi = {10.1118/1.4956652},
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}
}