UVA School of Medicine

Comparison Gamma Knife to CyberKnife

Gamma Knife versus CyberKnife
Setting the Record Straight

Competition to treat benign and malignant brain lesions, vascular malformations, and functional conditions with stereotactic radiosurgery (SRS) has increased dramatically in recent years. All-in-one systems like the Accuray’s CyberKnife are aggressively positioning themselves as being comparable to the Leksell Gamma Knife® in effectiveness and efficiency.

As one of the earliest and most experienced Gamma Knife centers in the world, we at the University of Virginia wish to address the competing LINAC based technologies such as Cyberknife.

Gamma Knife surgery is the gold standard for the treatment of intracranial pathology.  Its clinical efficacy has been documented across nearly four decades, with more than 400,000 cases treated worldwide providing the data for 2,000+ publications in peer-reviewed medical literature. It is used as the performance standard against which other technologies (such as CyberKnife) are measured.

Perhaps the easiest way to state our case is to compare, point for point, the Gamma Knife with the CyberKnife.

Gamma Knife	CyberKnife
201 source cobalt unit designed exclusively for non-invasive brain surgery, with 100x less radiation to the body than the Cyberknife, thereby decreasing the chance of radiation induced complications.	Single source linear accelerator with robotic arm to compensate for patient movement during treatment;  not exclusively used for intracranial SRS
Radiologic accuracy  better than 0.3mm	1 mm accuracy; dose outside the target area is 2-6x greater than with GK
Rigid immobilization to prevent head movement using a lightweight stereotactic head frame fixed to the outer skull.  Provides exact MR and CT correlation from planning to radiosurgical delivery in 3D.	Non-rigid immobilization reduces head movement by using a thermoplastic face mask that is shrink-wrapped to the table during treatment.  Provides relative MR and CT correlation from planning to treatment delivery in 3D.  The moving target and moving radiation source are inherently less accurate that a fixed target and fixed source.
Treatment delivered during one session	Single or multiple treatments, possibly over a period of days to weeks