Latest CyberKnife version uses fiducial tracking to treat tumours outside of the head

Sunnyvale 12 February 2002Stanford University Medical Center has treated its first 50 patients using the new CyberKnife Stereotactic Radiosurgery System with Dynamic Tracking Software (DTS). Stanford University Medical Center (SUMC) is the first site to conduct patient treatments using the newest CyberKnife system, developed by Accuray, specialised in advanced Image-Guided Radiosurgery. The new CyberKnife began operation in late 2001, with physicians treating an average of 5 to 6 patients a week.


SUMC has treated over 300 patients with its original prototype CyberKnife during the past several years and recently purchased the newest generation CyberKnife as part of a major upgrade to its radiosurgery programme. To date, over 2000 patients have been treated with the technology at multiple sites worldwide. Patients with lesions in the brain, spine, pancreas, liver, and lung have been treated.

The robotic, non-invasive CyberKnife system uses large doses of accurately targeted radiation fired from multiple directions to destroy tumours and other lesions while minimising damage to surrounding healthy tissue. CyberKnife with DTS is the first robotic system to receive FDA clearance to provide radiosurgery treatment of lesions anywhere in the body when radiation is indicated.

Steven Chang, M.D., Assistant Professor of Neurosurgery at SUMC, commented: "The new system allows us to maintain the highest level of patient care and has a new fiducial tracking feature for treating lesions outside of the head. As one of the most-experienced, leading CyberKnife centres in the world, Stanford also provides training for doctors and medical personnel from other CyberKnife centres acquiring the technology."

Among the new capabilities offered by the DTS system are greater accuracy and fiducial tracking, where small fiducials are implanted in the tumour to allow tracking of tumour position and compensation for changes due to patient movement during treatment delivery. For targets in the head, bony landmarks of the skull are used to track the tumour. Dr. Chang continued: "Treatment time is also faster with the new DTS software. We are currently averaging 25 patients a month with the system."

Thierry Thaure, Senior Vice President of Sales and Marketing at Accuray, added: "We are pleased with the launch of the DTS product and many of our existing sites are upgrading to the DTS software so they can bring the benefits of radiosurgery to areas outside of the head."

The impact however has been the greatest for patients like Tyler Holt, a 14 year-old boy suffering from neurofibromatosis, a genetic disorder where tumours develop along nerves throughout the body. There is no known cure. Typically, the tumours are surgically removed as they arise and Tyler has already undergone 10 open surgeries in his young life. He was recently diagnosed with a new tumour in his spinal cord near the area controlling speech. Doctors told him the location would make open surgery high risk. The CyberKnife was an ideal solution for him.

Dr. Chang, the treating neurosurgeon, stated: "Tyler's case illustrates the power of the technology. Conventional radiosurgical devices cannot treat outside of the head, so patients like Tyler would not have this non-invasive treatment option without the CyberKnife." Tyler was treated twice with the CyberKnife in December 2001 on an outpatient basis without anaesthesia. Instead of facing open surgery and recovery time in the hospital, he was able to return home immediately following treatment and resume normal activities.

The unique CyberKnife technology was developed in co-operation with Stanford University and was cleared by the FDA in August 2001 to provide radiosurgery for lesions anywhere in the body when radiation treatment is indicated. CyberKnife with Dynamic Tracking Software is the latest generation system which offers proprietary 6D skull and fiducial tracking features. Targets outside of the head are tracked in six dimensions through the use of small fiducials which are percutaneously implanted near the tumour and serve as reference points for tumour location.

During radiosurgical treatment, a proprietary image-guidance system tracks the position of the fiducials, and thus the tumour. Information about tumour position is communicated to the robotic arm, which can re-position the radiation-generating linear accelerator to compensate for changes in patient position. The CyberKnife is the only radiosurgical system in the world that precisely corrects for patient movement during actual treatment. The level of accuracy achievable by the system allows higher doses of radiation to be used, which provides the potential for greater tumour-killing efficacy and greater likelihood of cure.

More news about the CyberKnife technology is available in the following VMW August 2001 articles:

Leslie Versweyveld

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