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  • [J Appl Clin Med Phys.] Assessment of the accuracy and stability of frameless gamma knife radiosurgery.

    서울의대 / 정현태*

  • 출처
    J Appl Clin Med Phys.
  • 등재일
    2018 Jun 3. doi: 10.1002/acm2.12365. [Epub ahead o
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    Abstract
    The aim of this study was to assess the accuracy and stability of frameless gamma knife radiosurgery (GKRS). The accuracies of the radiation isocenter and patient couch movement were evaluated by film dosimetry with a half-year cycle. Radiation isocenter assessment with a diode detector and cone-beam computed tomography (CBCT) image accuracy tests were performed daily with a vendor-provided tool for one and a half years after installation. CBCT image quality was examined twice a month with a phantom. The accuracy of image coregistration using CBCT images was studied using magnetic resonance (MR) and computed tomography (CT) images of another phantom. The overall positional accuracy was measured in whole procedure tests using film dosimetry with an anthropomorphic phantom. The positional errors of the radiation isocenter at the center and at an extreme position were both less than 0.1 mm. The three-dimensional deviation of the CBCT coordinate system was stable for one and a half years (mean 0.04 ± 0.02 mm). Image coregistration revealed a difference of 0.2 ± 0.1 mm between CT and CBCT images and a deviation of 0.4 ± 0.2 mm between MR and CBCT images. The whole procedure test of the positional accuracy of the mask-based irradiation revealed an accuracy of 0.5 ± 0.6 mm. The radiation isocenter accuracy, patient couch movement accuracy, and Gamma Knife Icon CBCT accuracy were all approximately 0.1 mm and were stable for one and a half years. The coordinate system assigned to MR images through coregistration was more accurate than the system defined by fiducial markers. Possible patient motion during irradiation should be considered when evaluating the overall accuracy of frameless GKRS.

     


    Author information

    Chung HT1, Park WY2, Kim TH3, Kim YK3, Chun KJ4.
    1
    Department of Neurosurgery, Seoul National University College of Medicine, Seoul, Korea.
    2
    Department of Radiation Oncology, Chungbuk National University College of Medicine, Cheongju, Korea.
    3
    Department of Nuclear Engineering, Hanyang University College of Engineering, Seoul, Korea.
    4
    Department of Accelerator Science, Korea University Sejong Campus, Sejong-ro, Sejong, Korea.

  • 키워드
    frameless radiosurgery; gamma knife; image coregistration; positional accuracy; whole procedure test
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