When radiosurgery is recommended for a tumor or another condition in the brain, patients may encounter different names:
Gamma Knife, CyberKnife, LINAC…
All of these aim to provide treatment by directing radiation beams very precisely at a specific target. However, Gamma Knife has an important difference:
Gamma Knife is a specialized system developed from the outset specifically for the radiosurgery of diseases of the brain and inside the skull.
How does Gamma Knife work?
There is no actual knife or surgical incision with Gamma Knife.
In modern Gamma Knife systems, thin gamma rays emitted from 192 separate Cobalt-60 sources, are directed from different angles toward the point in the brain to be treated.
Individually, the effects of these rays on the normal brain tissue they pass through are limited. However, the high radiation dose needed for treatment is produced in the target area where the rays converge.
You can think of this as many thin beams of light converging at a single point.
This system is specifically designed to treat small, delicate intracranial targets with high accuracy [1,2].
Gamma Knife’s most important advantage: precision
When radiosurgery is performed in the brain, even a few millimeters can matter.
A tumor may be located immediately next to the optic nerve, brainstem, or an important nerve. Therefore, it is necessary not only to deliver an adequate dose to the target but also to preserve the normal brain tissue surrounding the target as much as possible.
One of Gamma Knife’s strongest features is its special stereotactic design that can provide submillimetric geometric precision, meaning precision of less than one millimeter [1].
This high precision is particularly important in:
- -small brain tumors,
- -lesions near critical brain structures,
- -multiple small metastases,
- -treatments targeting a very small nerve area, such as trigeminal neuralgia
.
In a multicenter dose verification study evaluating different radiosurgery systems, Gamma Knife demonstrated one of the lowest deviations among the platforms studied in terms of the difference between the planned dose and the dose actually measured [2].
For this reason, Gamma Knife is one of the systems that has been used worldwide for many years, particularly in intracranial radiosurgery, and has become synonymous with high precision.
So, can other devices not perform radiosurgery?
Of course they can.
Modern LINAC and CyberKnife systems can also perform highly precise radiosurgery treatments.
LINAC devices generate high-energy X-rays and can be used for radiotherapy in both the brain and many different areas of the body.
CyberKnife works on the principle of mounting a small linear accelerator on a robotic arm and can likewise be used in many areas of the body outside the brain.
The fundamental difference with Gamma Knife is that it is not a multipurpose radiotherapy device, but a specialized system developed specifically for intracranial radiosurgery.
The International Stereotactic Radiosurgery Society (ISRS) states that Gamma Knife, CyberKnife, and modern LINAC systems suitable for radiosurgery can be used effectively under appropriate technical conditions [3].
Therefore, it is not correct to say that a treatment will be successful or unsuccessful based solely on the name of the device.
What are the advantages of Gamma Knife?
The prominent advantages of Gamma Knife in intracranial radiosurgery include:
- -It was developed specifically for brain radiosurgery.
- -It can provide submillimetric geometric precision.
- -Very small targets can be treated precisely.
- -It aims to preserve normal brain tissue through the rapid decrease in radiation dose around the target.
- -Multiple brain metastases can be treated in the same session.
- -In addition to tumors, it can also be used for certain vascular and functional conditions, such as AVM and trigeminal neuralgia.
- -With modern Gamma Knife systems, treatment can be performed in a single session or divided into several sessions in appropriate patients.
However, there is a very important point here.
As important as the device: the team using it
It is understandable that patients may sometimes focus all their attention on the brand of the device.
However, the device alone does not determine the results of radiosurgery.
In radiosurgery treatment, MRI images must first be evaluated correctly. The boundaries of the target to be treated must be accurately outlined, an appropriate dose must be selected, critical brain structures must be protected, and the treatment plan must be tailored to the patient.
Each of these requires experience.
Therefore, one of the important questions for a patient should not only be:
“Which device is being used?”
but also,
“How long and how often has this team been performing this treatment?”
.
International radiosurgery guidelines also emphasize that, for modern radiosurgery to be performed safely, not only technology but also substantial expertise, experience, and appropriate quality-control infrastructure are needed [3].
A center’s use of Gamma Knife for many years provides an important accumulation of experience for treatment decisions, having encountered different tumors, different anatomic locations, and different clinical situations in a large number of patients.
Because good radiosurgery treatment is not just about hitting the target.
Knowing which patient should be treated, which patient should undergo surgery, which patient is better served by follow-up alone, and which dose should be used is also an important part of radiosurgery.
Conclusion
Unlike other radiosurgery systems, Gamma Knife is a specialized system developed specifically for the radiosurgery of diseases of the brain and inside the skull, with very high geometric precision.
This precision can provide an important advantage, especially in treating small targets or targets near critical brain structures.
However, successful radiosurgery treatments can also be performed today with modern LINAC and CyberKnife systems.
Therefore, the most important issue for a patient is not merely the name of the device.
What truly matters is selecting the right treatment for the right patient and having that treatment performed by a team with many years of experience in radiosurgery.
When Gamma Knife’s technological precision is combined with the clinical experience of an experienced radiosurgery team, this method becomes an extremely powerful option for treating intracranial diseases.
References
1. Elekta. Leksell Gamma Knife stereotactic radiosurgery. Technical information on the intracranial radiosurgery-specific design and submillimetric geometric precision of Gamma Knife systems.
2. Dimitriadis A, et al. Multi-institutional dosimetric delivery assessment of intracranial stereotactic radiosurgery on different treatment platforms. Radiother Oncol. 2020. PMID: 32445860.
3. Grishchuk D, Dimitriadis A, Sahgal A, et al. ISRS Technical Guidelines for Stereotactic Radiosurgery: Treatment of Small Brain Metastases (≤1 cm in Diameter). Pract Radiat Oncol. 2023;13(3):183–194. doi:10.1016/j.prro.2022.10.013.
4. Dharnipragada R, Dusenbery K, Watanabe Y, Ferreira C, Chen CC. Comparison of Gamma Knife and Linear Accelerator radiosurgery of brain metastasis resection cavity: a systematic review and proportional meta-analysis. Clin Exp Metastasis. 2024;41(1):1–8.