CyberKnife to ablate brain tumours in infants and children using non-invasive radiosurgery

Sunnyvale 05 June 2002Physicians at the University of Texas (UT) Southwestern Medical Center in Dallas have used Accuray's CyberKnife Stereotactic Radiosurgery System to treat infants with brain tumours for the first time in the United States. The benefits of radiosurgery, which involves delivery of high doses of accurately targeted radiation to non-invasively ablate tumours, have not been available to infants and very young children in the past because of limitations of existing commercially available radiosurgical systems.

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The CyberKnife is an FDA-cleared, non-invasive device used for ablation of tumours and other lesions located throughout the body. Multiple beams of radiation are delivered by a robot-mounted linear accelerator and converge upon the tumour, destroying it while minimising exposure to surrounding healthy tissue. The combination of robotics and image-guidance is unique to the CyberKnife and enables application to targets throughout the body.

The CyberKnife has been used successfully for several years for treatment of primarily older paediatric and adult populations. The use of the CyberKnife to address the young paediatric population, infants in particular, was pioneered at UT Southwestern Medical Center in Dallas by Cole Giller, M.D., Ph.D., Associate Professor of Neurological Surgery.

"The CyberKnife offers new hope for families of infants with tumours who often have no other treatment option available to them. Conventional radiotherapy cannot be used to treat brain tumours in young children because of the devastating effects on thinking and memory later on in life. Nor is traditional radiosurgery an option, since traditional radiosurgical devices require that a metal frame be bolted into the patient's skull in order to accurately target the radiation to the tumour. The skulls of infants, however, are thin and fragile so these frames cannot be used", explained Dr. Giller.

"Since the advanced image-guidance system of the CyberKnife allows frameless radiosurgery, it is the ideal tool for the radiosurgical treatment of paediatric brain tumours. We are also hopeful that the hypo-fractionation regimens made possible by the CyberKnife will have a further beneficial role in the treatment of infants with brain tumours", stated Dr. Giller. Hypo-fractionation is the division of the radiation dose into smaller, safer doses over a period of days, typically 2 to 5, and is difficult to perform with frame-based systems.

Two infants and twelve children, ranging in age from 3 to 16 years old, have now been treated by Dr. Giller on the CyberKnife at UT Southwestern Medical Center. "The preliminary results for these young patients are very promising. Of all the patients treated, none have shown any adverse side effects", Dr. Giller added.

John Adler, M.D., Chief Medical Officer at Accuray, stated: "To be able to offer patients a surgical procedure that is non-invasive, painless, and outpatient is tremendous. Because of the elimination of the frame, the CyberKnife opens the field of radiosurgery to new populations of patients for whom the benefits could not be realised in the past. The paediatric population is just one example of a new market this technology can impact."

"The reasons why the CyberKnife is ideal for infants also make it ideal for treating other types of patients such as those with spinal tumours. Frame-based systems have limited radiosurgery to largely the brain, so patients with spinal tumours, like infants, now have a treatment option they did not have before with the CyberKnife", added Dr. Adler.

UT Southwestern focuses on research and treatment in several areas, including Alzheimer's disease, arthritis, bone and joint problems, burns, cancer, diabetes, heart disease, kidney disease, liver disease, neurological disorders, osteoporosis, pain management, and urology. UT Southwestern's 1100-member faculty includes four Nobel laureates, 13 members of the National Academy of Sciences, and 15 members elected to the Institute of Medicine, a national honour reserved for individuals of exceptional distinction and achievement in health sciences research, clinical care, and medical education.

The 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. Over 2000 patients have been treated worldwide. The latest generation CyberKnife system offers proprietary 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. 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 April 2002 article Californian Neurosurgery Centres of Excellence to acquire CyberKnife with DTS for non-invasive tumour ablation.


Leslie Versweyveld

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