Beam energy metrics for the acceptance and quality assurance of Halcyon linear accelerator.

Autor: Gao S; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA., Chetvertkov MA; GenesisCareUS, Madison Heights, MI, USA., Cai B; Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA., Dwivedi A; Radiation Oncology, Rutgers CINJ/Robert Wood, Johnson University Hospital, New Brunswick, NJ, USA., Mihailidis D; Radiation Oncology, University of Pennsylvania, Philadelphia, PA, USA., Ray X; Radiation Medicine and Applied Science, University of California San Diego, Moores Cancer Center, La Jolla, CA, USA., Netherton T; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA., Court LE; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA., Simon WE; Sun Nuclear Corporation, Melbourne, FL, USA., Balter PA; Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Jazyk: angličtina
Zdroj: Journal of applied clinical medical physics [J Appl Clin Med Phys] 2021 Jul; Vol. 22 (7), pp. 121-127. Date of Electronic Publication: 2021 May 27.
DOI: 10.1002/acm2.13281
Abstrakt: Purpose: Establish and compare two metrics for monitoring beam energy changes in the Halcyon platform and evaluate the accuracy of these metrics across multiple Halcyon linacs.
Method: The first energy metric is derived from the diagonal normalized flatness (F DN ), which is defined as the ratio of the average measurements at a fixed off-axis equal distance along the open profiles in two diagonals to the measurement at the central axis with an ionization chamber array (ICA). The second energy metric comes from the area ratio (AR) of the quad wedge (QW) profiles measured with the QW on the top of the ICA. Beam energy is changed by adjusting the magnetron current in a non-clinical Halcyon. With D 10cm measured in water at each beam energy, the relationships between F DN or AR energy metrics to D 10cm in water is established with linear regression across six energy settings. The coefficients from these regressions allow D 10cm (F DN ) calculation from F DN using open profiles and D 10cm (QW) calculation from AR using QW profiles.
Results: Five Halcyon linacs from five institutions were used to evaluate the accuracy of the D 10cm (F DN ) and the D 10cm (QW) energy metrics by comparing to the D 10cm values computed from the treatment planning system (TPS) and D 10cm measured in water. For the five linacs, the D 10cm (F DN ) reported by the ICA based on F DN from open profiles agreed with that calculated by TPS within -0.29 ± 0.23% and 0.61% maximum discrepancy; the D 10cm (QW) reported by the QW profiles agreed with that calculated by TPS within -0.82 ± 1.27% and -2.43% maximum discrepancy.
Conclusion: The F DN -based energy metric D 10cm (F DN ) can be used for acceptance testing of beam energy, and also for the verification of energy in periodic quality assurance (QA) processes.
(© 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)
Databáze: MEDLINE
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