STUDY OF IRRADIATION ERROR WITH THE CYBERKNIFE II DUE TO HEAD ROTATION DURING TREATMENT

DOI 13 References
  • INOUE Mitsuhiro
    Division of Quality Management with Radiotherapy, Yokohama CyberKnife Center
  • SATO Kengo
    Department of Neurosurgery, Yokohama CyberKnife Center
  • KOIKE Izumi
    Department of Radiology, Yokohama City University Hospital

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Other Title
  • CyberKnife IIにおける治療中の頭部回転に起因する照射誤差の検討

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Abstract

Purpose: CyberKnife II (CK) enables stereotactic radiation therapy with frameless by a unique technology, and achieves an excellent treatment result. CK can recognize with 6D but correct with 3D on the treatment. Therefore CK users make threshold value of rotation with head, and CK will stop automatically when patient move over the threshold value. This study evaluates the irradiation error due to this threshold value. Methods: The tumor distances from TLS’s center were analyzed in 50 patients treated our center. To calculate the displacement distance of the tumor as head rotated based on the data. To re-create of rotating patient condition on the TPS and we evaluated the radiation dose and distribution. Results: The more distance from TLS’s center the tumor has, the more displacement the tumor has. The model rotating 0.7 degree and translating (total movement was less than 1 mm) were almost similar, and they had over 20% dose error in the maximum. The dose error were over 30% with rotating 1.0 degree and over 70% with rotating 2.0 degree in the maximum. Conclusion: CK users should understand that the irradiation error increases according to the head rotation. Therefore we need to pay attention to decide the threshold value of the head rotation.

Journal

  • The Journal of JASTRO

    The Journal of JASTRO 18 (3), 125-133, 2006

    Japanese Society for Therapeutic Radiology and Oncology

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