Gamma Knife Vs. Linear Accelerator/LINAC (including Cyberknife)

Patients who have been diagnosed with a condition suitable for intracranial radiosurgery are faced with two options: the Gamma Knife, the oldest and most proven technology (over 750,000 patients treated on four different generations of equipment), or a linear accelerator (including Cyberknife).  While both technologies are up to the task, three significant physical differences separate the two technologies in terms of safety and efficacy.

Measured Accuracy

The Gamma Knife Perfexion used at Rocky Mountain Gamma Knife Center measures accuracy in microns, the smallest meaningful measurement for equipment of this type. Even though they are also highly accurate, LINAC’s only approach this figure to an order of magnitude.

Designed exclusively for brain surgery.

Measured radiological accuracy down to 0.15mm*.

Provides exact MR and CT corrilation from planning to treatment delivered in 3D.

Head-frame based positioning is inheriently more accurate than CyberKnife, because it is not optically guided.

Not designed exclusively for brain surgery.

Measured radiological accuracy down to 1.10mm.

Provides relative MR and CT corrilation from planning to treatment delivered in 3D.

CyberKnife is inherently less accurate because head positioning is optically guided.


The most powerful difference between the technologies lies in the enormous tissue-sparing characteristics of the Gamma Knife. While the focal point of the Perfexion’s 192 beams of gamma radiation is intense enough to destroy tumors, each individual beam is only carrying around one-half of a percent of the energy aimed at the target as it passes through normal brain tissue. This is why the Gamma Knife has achieved its universal reputation for the highest level of safety.

As the most accurate of all SRS technologies, insures lowest does to normal brain tissue.

Target area is confirmed 10x / second.

2-6x higher dose to normal brain tissue than with Gamma Knife.**

Target area is confirmed once / 10 seconds.

Session Duration

Lastly, the ability to use a frame attached to the head removes any possibility of patient movement during the treatment, thus maximizing the incredible mechanical accuracy and making possible the “one-time, one-day” treatment the Gamma Knife is famous for. In order to perform the same treatments in a safe manner, LINACS require that the treatments be spread over several sessions/days as well as the use of complex movement tracking hardware and software.

A lightweight stereotactic frame is affixed to the head to provide rigid stabilization for maximum accuracy.

Treatment is delivered in one session.

Non-rigid immobilization reduces head movement by using thermoplastic face mask that is shrink wrapped to the table during treatment.

Single or multiple treatements, possibly over a period of several days.