Commissioning of optical surface imaging systems for cranial frameless stereotactic radiosurgery.

Autor: Zhang L; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Vijayan S; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Huang S; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Song Y; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Bergen, NJ, USA., Li T; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Commack, NY, USA., Li X; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Nassau, NY, USA., Hipp E; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Monmouth, NJ, USA., Chan MF; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Baskin Ridge, NJ, USA., Kuo HC; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Norwalk, CT, USA., Tang X; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Westchester, NY, USA., Tang G; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Lim SB; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Lovelock DM; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Ballangrud A; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA., Li G; Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Jazyk: angličtina
Zdroj: Journal of applied clinical medical physics [J Appl Clin Med Phys] 2021 May; Vol. 22 (5), pp. 182-190. Date of Electronic Publication: 2021 Mar 29.
DOI: 10.1002/acm2.13240
Abstrakt: Purpose: This study aimed to evaluate and compare different system calibration methods from a large cohort of systems to establish a commissioning procedure for surface-guided frameless cranial stereotactic radiosurgery (SRS) with intrafractional motion monitoring and gating. Using optical surface imaging (OSI) to guide non-coplanar SRS treatments, the determination of OSI couch-angle dependency, baseline drift, and gated-delivered-dose equivalency are essential.
Methods: Eleven trained physicists evaluated 17 OSI systems at nine clinical centers within our institution. Three calibration methods were examined, including 1-level (2D), 2-level plate (3D) calibration for both surface image reconstruction and isocenter determination, and cube phantom calibration to assess OSI-megavoltage (MV) isocenter concordance. After each calibration, a couch-angle dependency error was measured as the maximum registration error within the couch rotation range. A head phantom was immobilized on the treatment couch and the isocenter was set in the middle of the brain, marked with the room lasers. An on-site reference image was acquired at couch zero, the facial region of interest (ROI) was defined, and static verification images were captured every 10° for 0°-90° and 360°-270°. The baseline drift was assessed with real-time monitoring of the motionless phantom over 20 min. The gated-delivered-dose equivalency was assessed using the electron portal imaging device and gamma test (1%/1mm) in reference to non-gated delivery.
Results: The maximum couch-angle dependency error occurs in longitudinal and lateral directions and is reduced significantly (P < 0.05) from 1-level (1.3 ± 0.4 mm) to 2-level (0.8 ± 0.3 mm) calibration. The MV cube calibration does not further reduce the couch-angle dependency error (0.8 ± 0.2 mm) on average. The baseline drift error plateaus at 0.3 ± 0.1 mm after 10 min. The gated-delivered-dose equivalency has a >98% gamma-test passing rate.
Conclusion: A commissioning method is recommended using the 3D plate calibration, which is verified by radiation isocenter and validated with couch-angle dependency, baseline drift, and gated-delivered-dose equivalency tests. This method characterizes OSI uncertainties, ensuring motion-monitoring accuracy for SRS treatments.
(© 2021 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)
Databáze: MEDLINE
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