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 CyberKnife^® are aggressively positioning themselves as being comparable to the Leksell Gamma Knife^® in effectiveness and efficiency.

As one of the most experienced Gamma Knife treatment teams at one of the most active Gamma Knife centers in the country, we at Wake Forest University Baptist Medical Center feel compelled to set the record straight.

Gamma Knife stereotactic radiosurgery is the gold standard for the treatment of intracranial SRS procedures. Its clinical efficacy has been documented across nearly 4 decades, with more than 350,000 cases treated worldwide providing the data for 2,000+ publications in peer-reviewed medical literature. It is used as the performance metric 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	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 treatment delivery in 3-D.	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 3-D. The CK is inherently less accurate since the positioning is optically guided, not head-frame based.
Treatment delivered during one session	Single or multiple treatments, possibly over a period of days
Target position is confirmed 10 times per second	Target position confirmed once every 10 seconds