Physics·Biology·Technique
Performance Evaluation of a CyberKnife VSI™ System
Xile Zhang, Ruijie Yang, Jun Li, Lu Liu, Junjie Wang
Published 2018-10-15
Cite as Chin J Radiat Oncol, 2018, 27(10): 925-929. DOI: 10.3760/cma.j.issn.1004-4221.2018.10.011
Abstract
ObjectiveTo evaluate the accuracy and reliability of the CyberKnife VSI system for stereotactic radiotherapy.
MethodsFirst, the mechanical accuracy of the robotic manipulator system, the repeatability of the Iris variable aperture collimator system, the couch position accuracy of the patient positioning system, the tacking precision of the target locating system and the dosimetric beam characteristics of the linac system for each subsystem of CyberKnife VSI system were tested. Finally, the total beam delivery precision of the CyberKnife VSI system was evaluated.
ResultsThe mean positioning deviations of the mechanical arm movement of the robotic manipulator system were less than 0.1 mm, and the maximum positioning deviation of single note was ≤ 0.29 mm. The repeatability of the aperture sizes for the Iris variable aperture collimator system was ≤ 0.28 mm. The couch position accuracy of the patient positioning system was<0.2 mm and the tracking precision of the target locating system was less than 0.5°. The linac beam-laser beam axes coincidence between the Iris and fixed collimators was better than 0.4 mm. The 6-MV beam parameters, such as beam quality and profile, were found within the acceptance limits. The deviations of output reproducibility, linearity and constancy versus linac orientation were less than 1.0%. The transmission factors of two types of collimators were lower than 0.4%. End-to-end test demonstrated that the maximum deviation of the total delivery precision of CyberKnife VSI system was 0.87 mm.
ConclusionThe CyberKnife VSI system is accurate and reliable for stereotactic radiotherapy.
Key words:
CyberKnife VSI system; Performance evaluation; Iris variable aperture collimator system; Stereotactic radiotherapy
Contributor Information
Xile Zhang
Department of Radiation Oncology, Peking University Third Hospital, Beijing 100191, China
Ruijie Yang
Jun Li
Lu Liu
Junjie Wang
