Stereotactic radiosurgery - CyberKnife
Stereotactic radiosurgery (SRS) is a form of radiation therapy that focuses high-power energy on a small area of the body. Despite its name, radiosurgery is a treatment, not a surgical procedure. Incisions (cuts) are not made on your body.
More than one system is used to perform radiosurgery. This article is about radiosurgery using CyberKnife.
During treatment you lie on a table, which slides into a machine that delivers radiation:
- A robotic arm controlled by a computer moves around you. It focuses radiation exactly on the area being treated.
- You are not put to sleep. The treatment does not cause pain.
The nurses and doctors can see you on cameras. They can hear you and talk with you on microphones.
Each treatment takes about 30 minutes to 2 hours. Some patients receive more than one treatment session, but usually no more than five sessions.
Stereotactic radiotherapy; SRT; Stereotactic body radiotherapy; SBRT; Fractionated stereotactic radiotherapy; SRS
Why the Procedure Is Performed
SRS targets and treats an abnormal area without damaging nearby healthy tissue. SRS is more likely to be recommended for patients who are too high risk for surgery. This may be due to age or other health problems. Or it may be because the area to be treated is too close to important structures inside the body.
CyberKnife is often used to slow the growth of small, deep brain tumors that are hard to remove during surgery that involves incisions.
Tumors of the brain and nervous system that can be treated using CyberKnife include:
- Cancer that has spread (metastisized) to the brain from another part of the body
- A slow-growing tumor of the nerve that connects the ear to the brain (acoustic neuroma
- Pituitary tumors
- Spinal cord tumors
Other cancers that can be treated include:
- A type of skin cancer (melanoma) that involves the eye
Other medical problems treated with CyberKnife are:
SRS may damage tissue around the area being treated. As compared to other types of radiation therapy, CyberKnife treatment is much less likely to damage nearby healthy tissue.
Brain swelling may occur in people who receive treatment to the brain. Swelling usually goes away without treatment. But some people may need medicines to control this swelling. In rare cases, surgery with incisions (open surgery) is needed to treat the brain swelling caused by the radiation.
Before the Procedure
Before the treatment, you will have MRI
scans. These images help your doctor determine the specific treatment area.
The day before your procedure:
- Do not use any hair creams or hair spray if CyberKnife surgery involves your brain.
- Do not eat or drink anything after midnight unless told otherwise by your doctor.
The day of your procedure:
- Wear comfortable clothing.
- Bring your regular prescription medicines with you to the hospital.
- Do not wear jewelry, makeup, nail polish, or a wig or hairpiece.
- You will be asked to remove contact lenses, eyeglasses, and dentures.
- You will change into a hospital gown.
- An intravenous (lV) line will be placed into your arm to deliver contrast material, medicines, and fluids.
After the Procedure
Often, you can go home about 1 hour after the treatment. Arrange ahead of time for someone to drive you home. You can go back to your regular activities the next day if there are no complications such as swelling. If you have complications, you may need to stay in the hospital overnight for monitoring.
The effects of CyberKnife treatment may take weeks or months to be seen. Prognosis depends on the condition being treated. Your health care provider will likely monitor your progress using imaging tests such as MRI and CT scans.
Chang EF, Quigg M, Oh MC, et al. Epilepsy Radiosurgery Study Group. Predictors of efficacy after stereotactic radiosurgery for medial temporal lobe epilepsy. Neurology. 2010;74:165-172.
Suh JH. Stereotactic radiosurgery for the management of brain metastases. N Engl J Med. 2010;362:1119-1127.
Welling DB, Packer MD. Stereotactic radiation treatment of benign tumors of the cranial basae. In: Flint PW, Haughey BH, Lund VJ, et al., eds. Cummings Otolaryngology: Head & Neck Surgery. 5th ed. Philadelphia, PA: Elsevier Mosby; 2010:chap 179.
Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.