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Original article
peer-reviewed

Feasibility of Fiducial-Free Prone-Position Treatments with CyberKnife for Lower Lumbosacral Spine Lesions



Abstract

Objective: For spinal CyberKnife (CK) treatments, prone patient position can yield a dosimetric advantage for posterior lesions, but the target can be subject to respiratory motion. We treated 17 lower lumbosacral lesions in prone position using CK fiducial-free XsightTM spine tracking and analyzed motion data in order to establish an adequate margin concept.

Methods: The lumbar spine and pelvis were elevated and stabilized to decouple the target from respiration. The tracking region of interest was centered at the lumbar vertebrae L4/L5. Pairs of X-ray images were taken periodically (1.4 per minute) during treatment. Tracking data from two periods of 6 to 15 minutes per treatment were analyzed to assess the extent of breathing-induced motion.

Results: Stochastic motion in left/right and superior/inferior direction was small, with peak amplitudes of 0.40±0.20 mm and 0.58±0.31 mm. Anterior/posterior spine motion was significantly increased with a peak amplitude of 1.27±0.50 mm, and was positively correlated with a head-down/-up tilt of the spine due to breathing.

Conclusions: Fiducial-free prone treatments of the lower lumbar and sacral spine are feasible using XsightTM spine tracking and proper immobilization. The residual impact of respiratory motion can be compensated with an additional PTV margin of 3 mm.



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Original article
peer-reviewed

Feasibility of Fiducial-Free Prone-Position Treatments with CyberKnife for Lower Lumbosacral Spine Lesions


Author Information

Christoph Fürweger Corresponding Author

Chief Medical Physicist, European CyberKnife Center Munich

Christian G. Drexler

Varian Medical Systems International

Markus Kufeld

Charité Cyberknife Center Berlin

B. Wowra

European Cyberknife Center Munich-Grosshadern


Ethics Statement and Conflict of Interest Disclosures

Human subjects: Consent was obtained by all participants in this study. N/A issued approval N/A. This study was not part of an IRB protocol. Animal subjects: This study did not involve animal subjects or tissue. Conflicts of interest: The authors have declared that no conflicts of interest exist.


Original article
peer-reviewed

Feasibility of Fiducial-Free Prone-Position Treatments with CyberKnife for Lower Lumbosacral Spine Lesions


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Original article
peer-reviewed

Feasibility of Fiducial-Free Prone-Position Treatments with CyberKnife for Lower Lumbosacral Spine Lesions

  • Author Information
    Christoph Fürweger Corresponding Author

    Chief Medical Physicist, European CyberKnife Center Munich

    Christian G. Drexler

    Varian Medical Systems International

    Markus Kufeld

    Charité Cyberknife Center Berlin

    B. Wowra

    European Cyberknife Center Munich-Grosshadern


    Ethics Statement and Conflict of Interest Disclosures

    Human subjects: N/A issued approval N/A. This study was not part of an IRB protocol. Animal subjects: This study did not involve animal subjects or tissue.

    Acknowledgements


    Article Information

    Published: January 23, 2011

    DOI

    10.7759/cureus.21

    Cite this article as:

    Fürweger C, Drexler C G, Kufeld M, et al. (January 23, 2011) Feasibility of Fiducial-Free Prone-Position Treatments with CyberKnife for Lower Lumbosacral Spine Lesions. Cureus 3(1): e21. doi:10.7759/cureus.21

    Publication history

    Published: January 23, 2011

    Copyright

    © Copyright 2011
    Fürweger et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 3.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    License

    This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Objective: For spinal CyberKnife (CK) treatments, prone patient position can yield a dosimetric advantage for posterior lesions, but the target can be subject to respiratory motion. We treated 17 lower lumbosacral lesions in prone position using CK fiducial-free XsightTM spine tracking and analyzed motion data in order to establish an adequate margin concept.

Methods: The lumbar spine and pelvis were elevated and stabilized to decouple the target from respiration. The tracking region of interest was centered at the lumbar vertebrae L4/L5. Pairs of X-ray images were taken periodically (1.4 per minute) during treatment. Tracking data from two periods of 6 to 15 minutes per treatment were analyzed to assess the extent of breathing-induced motion.

Results: Stochastic motion in left/right and superior/inferior direction was small, with peak amplitudes of 0.40±0.20 mm and 0.58±0.31 mm. Anterior/posterior spine motion was significantly increased with a peak amplitude of 1.27±0.50 mm, and was positively correlated with a head-down/-up tilt of the spine due to breathing.

Conclusions: Fiducial-free prone treatments of the lower lumbar and sacral spine are feasible using XsightTM spine tracking and proper immobilization. The residual impact of respiratory motion can be compensated with an additional PTV margin of 3 mm.



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Create a free account to continue reading this article.

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Christoph Fürweger, Ph.D.

Chief Medical Physicist, European CyberKnife Center Munich

For correspondence:
christoph.fuerweger@cyber-knife.net

Christian G. Drexler, M.Sc.

Varian Medical Systems International

Markus Kufeld, M.D.

Charité Cyberknife Center Berlin

B. Wowra, None

European Cyberknife Center Munich-Grosshadern

Christoph Fürweger, Ph.D.

Chief Medical Physicist, European CyberKnife Center Munich

For correspondence:
christoph.fuerweger@cyber-knife.net

Christian G. Drexler, M.Sc.

Varian Medical Systems International

Markus Kufeld, M.D.

Charité Cyberknife Center Berlin

B. Wowra, None

European Cyberknife Center Munich-Grosshadern