What is radiosurgery?
Radiosurgery, also called stereotactic radiosurgery, is a very precise form of therapeutic
radiology. Even though it is called surgery, radiosurgery does not involve actual
surgery. Instead, very focused beams of radiation (gamma rays, X-rays, or protons)
are used to treat cancerous tissues without a surgical incision or opening.
Radiosurgery is called "surgery" because it is a 1-session radiation therapy treatment
that creates a similar result as an actual surgical procedure.
How does radiosurgery work?
Radiosurgery works in the same manner as other types of therapeutic radiology. It
distorts or destroys the DNA of tumor cells, causing them to be unable to reproduce
and grow. The tumor will shrink in size over time. For blood vessel lesions, like
an arteriovenous malformation (AVM), the blood vessels eventually close off after
What are the types of radiosurgery?
There are three types of radiosurgery. Each type uses different equipment and radiation
sources. Radiosurgery types include:
Cobalt60 systems (Gamma Knife). Cobalt60 systems use cobalt as a source for gamma rays. This type of system is commonly
referred to as the Gamma Knife. The Gamma Knife is not really a knife at all. It uses
beams of highly-focused gamma rays to treat small- to medium-size lesions, usually
in the brain. Many beams of gamma radiation join to focus on the lesion under treatment,
providing a very intense dose of radiation in a safe manner.
The Gamma Knife is used primarily to treat small and medium lesions in and around
the brain, like brain tumors, arteriovenous malformations (abnormal connections between
arteries and veins), as well as functional problems, like trigeminal neuralgia.
During Gamma Knife treatment, the equipment remains stationary (does not move).
Gamma Knife treatment generally involves these steps:
Head frame placement. In order to keep the head from moving during treatment, a box-shaped frame is attached
to the head. Pins designed specifically for this purpose fasten the head frame to
the skull. The head frame also is a guide to focus the gamma ray beams to the exact
location of the lesion being treated.
Tumor location imaging. Once the head frame is in place, the exact location of the lesion to be treated will
be determined using computed tomography (CT scan) or magnetic resonance imaging (MRI).
Radiation dose planning. After the CT or MRI scan has been completed, the radiation therapy team will determine
the treatment plan. The results of the imaging scan, along with other information,
will be used by a medical physicist to determine the best treatment.
Radiation treatment. After being positioned for the treatment, a type of helmet with many hundreds of holes
in it is placed over the head frame. These holes help to focus the radiation beams
on the target. Treatment will last a few minutes up to a few hours. This depends on
the type and location of the area being treated. Generally, only 1 treatment session
is required for a lesion.
Linear accelerator (LINAC) systems. Linear accelerator (LINAC) systems use high-energy X-rays to treat large tumors or
other lesions outside of the brain. Some common types of LINAC systems include CyberKnife,
X-Knife, Novalis, and Peacock.
In addition to not using radioactive material to produce the radiation, LINAC systems
also differ from the Gamma Knife in that the machinery moves around the patient during
treatment. For this reason, LINAC systems are able to treat larger tumors and larger
affected areas than the Gamma Knife. Areas other than the brain can be treated with
a LINAC system.
Linear accelerator systems may also be used for external beam radiation therapy.
Treatment steps with a LINAC system are generally the same or similar to the treatment
steps used for the Gamma Knife.
Proton beam therapy. Proton beam therapy is a type of particle beam radiation therapy. Rather than using
rays of radiation, like gamma rays or X-rays, particle beam therapy uses particles,
like protons or neutrons. Proton beam therapy is the most widely-used type of particle
Proton beam therapy is useful in treating tumors or lesions that are small and/or
have an irregular shape. The radiation dose can be more closely controlled with these
systems. The proton beam can be controlled to allow it to deposit its energy almost
completely in the tumor or lesion being treated. Other forms of radiation lose energy
as they enter body tissues on their way to the tissue under treatment.
Because the depth of the proton beam can be controlled so precisely, less damage happens
to normal tissues surrounding the area under treatment.
Proton beam therapy may be used for radiosurgery procedures or for fractionated radiotherapy
(several smaller doses of radiation over a certain period of time).
There are only a few facilities in North America that provide proton beam therapy.