CyberKnife®: Stereotactic Radiosurgery

The CyberKnife® Robotic Radiosurgery System.

Photo courtesy of Accuray Inc.

The CyberKnife is a radiosurgery system that destroys tumours or other lesions using beams of radiation, rather than a surgical knife. The radiation is precisely focused, minimizing damage to healthy surrounding tissue.

While other radiosurgery systems are restricted to intracranial treatments, the CyberKnife can deliver radiosurgery to any part of the body.

How it Works

The CyberKnife uses a linear accelerator (linac), mounted on a robotic arm, to produce a high energy “killing beam” of radiation. In contrast to standard stereotactic techniques where a rigid metal frame is bolted to the patient’s skull to restrict movements, the CyberKnife uses two ceiling-mounted x-ray cameras to guide the imaging in “real time” and makes constant adjustments for slight movements. Patients with extracranial tumours or lesions may need to have metallic markers implanted to target the area and guide treatment.

Regulatory Status

The CyberKnife (Accuray Inc.) was licensed by Health Canada in August 2006;[1] however, to date, no CyberKnife units have been installed in Canada. According to the CyberKnife Society, there are more than 80 CyberKnife units operating worldwide, with about 50 in US centres.[2]

Evidence

Randomized controlled trials that compare patient outcomes and costs for CyberKnife treatments to those using other radiosurgery systems have not been published. Most of the available evidence is limited to case studies reporting the use of CyberKnife treatments for various conditions.

Several health technology assessments have reviewed the evidence on the CyberKnife.[3-5] These reports concur that, at present, there is insufficient good quality evidence available to determine the efficacy and safety of the CyberKnife relative to other stereotactic radiosurgery techniques.

Cost

The CyberKnife costs approximately US$4 million, which includes the manufacturer’s guidance during installation and staff training. Additional capital costs include facility construction or renovations to house the CyberKnife and special radiation shielding requirements.

A 2003 economic evaluation compared the costs of CyberKnife, Gamma Knife and Novalis stereotactic radiosurgery for neurological applications, including equipment, staffing and annual unit costs, with estimated patient loads based on modelling for Alberta.[6] A 2006 ECRI assessment outlined additional costs that might be involved, including installation costs, extended warranties, closed-circuit cameras to monitor patients during treatment, and workstations for treatment planning.[5] The estimated life expectancy of the CyberKnife system is 10 years.

References

[1] Medical devices active license listing [database online]. Ottawa: Medical Devices Bureau, Therapeutic Products Directorate, Health Canada; 2006. Available: http://www.mdall.ca/

[2] CyberKnife Society. CyberKnife site locations. Sunnyvale (CA): The Society; 2006. Available: http://www.cksociety.org/PatientInfo/CKSites/cyberknife_locations.asp

[3] Hodgkinson B, Merlin T. CyberKnife®: minimally invasive precision radiosurgery for conditions where radiation treatment is indicated [Horizon scanning prioritising summary v.3 no.3]. Canberra, Australia: Adelaide Health Technology Assessment (AHTA); 2004. Available: http://www.health.gov.au/internet/horizon/publishing.nsf/Content/69B0FEB887C255CACA2571550012ADAA/$File/v3_3.pdf

[4] Efectividad, seguridad y estimacion de costes del sistema de radiocirugia Cyberknife: effectiveness, safety and cost estimation of cyberknife radiosurgery system. Madrid: Unidad de Evaluacion de Tecnologias Sanitarias (UETS); 2005. Report no.: IT01/2005.

[5] Frameless stereotactic radiosurgery (overview). [Target report no. 899]. Plymouth Meeting (PA): ECRI; 2006.

[6] Ohinmaa A. Cost estimation of stereotactic radiosurgery: application to Alberta. Edmonton: Alberta Heritage Foundation for Medical Research (AHFMR); 2003. Available: http://www.ihe.ca/documents/hta/ip14.pdf