Sometimes, surgery is not possible to treat a disease due to the location of the problem or the poor health of the patient. Brain tumors, blood vessel issues, and some nervous system conditions are very difficult to address with a scalpel. Stereotactic radiosurgery may be used to treat some of these problems.
Stereotactic radiosurgery is not true surgery because no cutting is involved. Instead, it is an advanced method of radiation therapy that delivers very strong doses of radiation to very small areas, killing a small group of cells very effectively. Stereotactic radiosurgery on areas of the body other than the brain may be referred to as stereotactic body therapy.
Why Is Stereotactic Radiosurgery Performed?
Stereotactic radiosurgery (SRS) is a type of radiation therapy that is very precise and very powerful. Instead of many doses of radiation therapy to treat a problem area, SRS usually consists of a single treatment of a very high dose of radiation in a very focused location. Sometimes, it may consist of a few treatments. Radiation therapy uses radiation to damage the DNA of tumor or other cells so they no longer reproduce and cause the tissue to die.
SRS was originally developed to treat small, deep brain tumors. Now it may be used for a wider array of problems in the brain as well as in the body. Problem areas that are hard to reach, close to vital organs, or may move within the body are treated with this method. Examples of problems that can be addressed with SRS include:
- deep brain tumors or residual tumor cells after surgery
- pituitary tumors
- cancers of the eye
- arteriovenous malformations (tangled blood vessels that leak and disrupt normal flow)
- neurological problems, such as trigeminal neuralgia
- tumors in the lung, liver, abdomen, spine, prostate, head and neck
- Parkinson’s disease
SRS may also be used to treat very elderly patients or patients who are too sick to undergo surgery. Sometimes, after surgery has been performed to remove a cancerous tumor, SRS is used to kill any remaining tumor cells that may have been missed by conventional surgery.
How Is Stereotactic Radiosurgery Done?
The three main kinds of treatments in stereotactic radiosurgery that use different equipment are:
- Gamma Knife: Close to 200 beams of highly focused gamma radiation are aimed at a target region (i.e. tumor). This is used mostly for small to medium-sized brain and/or head and neck abnormalities.
- linear accelerator (LINAC) machines: High energy X-rays are used to target large tumors. This is sometimes called CyberKnife technology
- proton beam or heavy charged particle radiosurgery: This is used for smaller tumors throughout the body.
These methods all require a lot of imaging with computed tomography (CT) scans, magnetic resonance imaging (MRI), and other methods. This is so doctors know exactly where your tumor is and how large it is.
You need to stay completely still for these methods to work. You may be strapped down to be immobile or have a special face mask or a frame attached to your scalp to keep you from moving during the therapy.
You will lie down on a table that slides into a machine. The machines used during the treatment may spin you around to change the angle of the radiation beams. Doctors and nurses will be watching the entire time on camera. You can speak to them through a microphone in the machine if you have any problems. Some of the professionals who may be caring for you will be a radiation oncologist, a medical radiation physicist, a radiologist, a dosimetrist, a radiation therapist, and/or a radiation therapy nurse.
Treatment usually takes between 30 minutes to one hour. Often only one session is needed, but there may be additional treatments as needed. SRS results will be seen over time.
How Do I Prepare for Stereotactic Radiosurgery?
You will have one or more imaging scans, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI). A contrast agent may be injected to help doctors understand the size and location of the tumor or other structure they need to treat. A lot of planning will go into structuring your treatment.
Tell your doctors about any medications you may be taking. Any devices or implants such as a pacemaker, artificial heart valve, implanted pumps, or stents need to be reported to your care team.
Do not eat after midnight the day of your treatment. Do not wear hair products like hair spray or mousse. Do not wear jewelry or makeup. Any eyeglasses, contact lenses, and dentures need to be removed before treatment.
An intravenous (IV) line will be started to give fluids, medications, and contrast agents into your bloodstream.
What Are the Risks of Stereotactic Radiosurgery?
Side effects may include:
- skin problems (red, swollen, peeling, or blistering)
- hair loss in treatment area
- difficulty swallowing
- nausea and vomiting
- swelling, especially in the brain
In the long term, there can be changes to the brain, the spinal cord, and the lungs. There is a slight risk of cancer from radiation treatments.
What Can Be Expected in the Long Term?
Long-term outlook really depends on the exact condition being treated. Radiation damages the DNA of the cells in the area being targeted. It may take weeks or months for those cells to stop reproducing and to die off. You will continue to have CT scans and MRI scans to look at the size of the tumor and the area that was treated.