Spinal robotic radiosurgery

Abstract

Spinal radiosurgery is a new class of procedures designed for primary or adjuvant treatment of certain spinal disorders [3, 6, 7, 9, 21, 23]. Because such large doses of radiation are administered, spinal radiosurgery, similar to its intracranial predecessor, requires extremely accurate targeting. In contrast, the lack of precision inherent in conventional external beam radiation therapy and the limitations of target immobilization techniques generally preclude large, single-fraction irradiation near radiosensitive structures, such as the spinal cord [5, 10, 23]. The frameless CyberKnife radiosurgery system has overcome these problems by using real-time image guidance, which allows the paraspinous target to be tracked even in the presence of occasional patient movement [12, 24]. Continuous tracking and correction for motion of the spine throughout treatment are prerequisites for spinal radiosurgery, because patients do move after set-up is complete [20]. Until recently, clinicians surgically implanted fiducials into the spine to track the movement of the lesion during treatment [12, 14, 21]. In the first reported use of image-guided robotics to perform spinal radiosurgery, Ryu and coworkers demonstrated the safety and short-term efficacy for a variety of neoplastic and vascular lesions [21]. Surgical implantation of fiducials into adjacent vertebral segments was necessary for tracking the ablated spinal lesion [15]. However, this step introduces the added surgical risks associated with an invasive surgery, lengthens treatment time, and reduces patient comfort. It would be ideal if it were possible to track spinal lesions using bony landmarks (similar to tracking intracranial lesions based on skull anatomy) instead of fiducials. Recently, such a fiducial-free spinal tracking system has been introduced (Xsight-Spine Tracking System, Accuray Incorporated) [16, 20, 22]. © 2010 Springer-Verlag Berlin Heidelberg.