FAQs
FAQs
The following FAQs can also be found at the Accuray website.
How many procedures have been performed using the CyberKnife® Robotic Radiosurgery System?
The CyberKnife System has been used to treat in excess of an estimated 20,000 patients worldwide. Currently more than 50 percent of all CyberKnife procedures in the United States are extracranial.
What intracranial tumors can be treated using the CyberKnife System that cannot be treated using conventional radiosurgery?
The CyberKnife System’s intelligent robotics enables the system to treat tumors that are difficult to reach with more conventional, frame-based systems. The CyberKnife System is the only robotic radiosurgery system that utilizes the skeletal structure of the body as a reference, eliminating the need for the invasive frame used with traditional radiosurgery systems. Additionally, the manipulator enables unlimited beam positions, which provides access to many tumors that are unreachable by other radiosurgery systems. Examples of intracranial tumors treated with the CyberKnife System not reachable by conventional radiosurgery systems include skull base tumors, meningiomas and metastases located in the low posterior fossa, foramen magnum, and upper cervical spine areas.
What areas outside the cranium can be treated using the CyberKnife System?
The CyberKnife System has been cleared by the FDA to treat tumors anywhere in the body where radiation treatment is indicated. Extracranial tumors that have been treated by the CyberKnife System include tumors of the spine, lung, prostate, liver, and pancreas.
Why should clinicians feel confident in the CyberKnife System's image guidance technology as an alternative to localization systems incorporating a conventional stereotactic head frame?
The CyberKnife System uses a combination of image guidance and computer controlled robotics to continuously track, detect and correct for tumor and patient movement throughout the treatment. Because of the extreme precision and accuracy of the CyberKnife System, no head or body frame is required to immobilize the patient for tumor tracking.
During treatment, the CyberKnife correlates live radiographic images with pre-operative CT or MRI scans to determine patient and tumor position repeatedly throughout the course of treatment. With the Synchrony® Respiratory Tracking System, patients can breathe normally throughout their treatment without breath-holding or gating techniques, enabling clinicians to continuously track, detect and correct for tumor and patient movement throughout the treatment.
With the CyberKnife System’s revolutionary Xsight™ Spine Tracking System it is now possible to treat tumors in or near spinal structures without implanting radiographic markers or fiducials.
How does Intensity Modulated Radiation Therapy (IMRT) differ from robotic radiosurgery and the CyberKnife System?
IMRT, Intensity Modulated Radiation Therapy, is a form of radiation therapy incorporating multi-leaf collimators on standard gantry-based linac delivery systems to better "shape" the radiation beams to the lesion volume. IMRT also utilizes inverse treatment planning software to optimize dose distribution. This is generally accepted as an improvement over conventional radiation therapy (XRT) systems; however it is still limited by many of the same constraints as conventional radiation therapy.
IMRT differs from CyberKnife radiosurgery in several fundamental ways:
• Accuracy — IMRT systems register target location only at the beginning of a treatment and cannot localize and compensate for a moving target during the actual treatment. The CyberKnife System combines image guidance and computer controlled robotics to continuously track, detect and correct for tumor and patient movement throughout the treatment, providing greater accuracy when compared to an IMRT system.
• Fractionation — Due to the large error margin and need to minimize damage to the surrounding healthy tissue, IMRT cannot deliver high doses of radiation (8-25 Gy per fraction). As a result, a higher number of treatment fractions (20-30 sessions) are delivered at a lower radiation dose (typically 2 Gy per fraction). Because the CyberKnife System is able to target and treat lesions more precisely, radiation doses can be increased and the number of fractions reduced to five or less.
• Flexibility — Compared to gantry-based IMRT, IGRT (Image Guided Radiation Therapy) and conventional radiosurgery systems, the CyberKnife System allows for greater flexibility. It offers non-isocentric delivery for improved conformality and offers both homogeneous and heterogeneous dose distribution options during treatment planning and delivery. The manipulator can be positioned in almost any orientation, providing maximum treatment delivery options compared to the constrained geometry of the gantry-based systems. The flexibility of the CyberKnife System helps the clinician to easily execute complex treatment plans, including those for non-symmetrical, complex-shaped lesions in difficult-to-reach locations. Less maneuverable systems make it difficult to achieve the same level of conformality and accuracy.
What is the average treatment time for the CyberKnife system?
The treatment time per session ranges from 30 to 90 minutes (including patient setup, beam-on and beam-off time) depending on the dose delivered and the complexity of the tumor shape. Physicians may elect to treat a patient with a single or a hypofractionated dose. Hypofractionated doses are typically performed over two to five fractions (or sessions).
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