SRS targets and treats an abnormal area of the body. Using many tiny beams, radiation is tightly focused on the cancer, which minimizes damage to nearby healthy tissue.

During treatment:

• You won't need to be put to sleep. The treatment does not cause pain.
• You lie on a table that 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.
• The health care providers are in another room. They can see you on cameras and hear you and talk with you on microphones.
• You may be given a small vest to wear during treatment, this allows the machine to better focus on the cancer and track your breathing.

Each treatment takes about 30 minutes to 2 hours. You may receive more than one treatment session, but usually no more than five sessions.

SRS is more likely to be recommended for people who are too high risk for conventional surgery. This may be due to age or other health problems. SRS may be recommended because the area to be treated is too close to vital structures inside the body.

CyberKnife is often used to slow the growth of or completely destroy small, deep brain tumors that are hard to remove using conventional surgery.

Tumors of the brain and nervous system that can be treated using CyberKnife include:

• Cancer that has spread (metastasized) 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:

• Breast
• Kidney
• Liver
• Lung
• Pancreas
• Prostate
• A type of skin cancer (melanoma) that involves the eye

Other medical problems treated with CyberKnife are:

• Blood vessel problems such as arteriovenous malformations
• Parkinson disease
• Severe tremors (shaking)
• Some types of epilepsy
• Trigeminal neuralgia (severe nerve pain of the face)

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 and tumor breakdown (called necrosis) 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.

For cancers near the ribs and chest wall, sometimes pain may develop or even a rib fracture months after treatment.

For some cancers near the top of the lung, nerves in the arm be damaged by the radiation in rare cases.

Before the treatment, you will have MRI or CT scans or both. You may also have a PET scan. These images help your radiation doctor (usually a radiation oncologist) determine the specific treatment area.

The day before your procedure:

• Do not use any hair cream or hair spray if CyberKnife surgery involves your brain.
• Do not eat or drink anything after midnight unless told otherwise by your radiation doctor.

The day of your procedure:

• Wear comfortable clothes.
• 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.

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.

Follow instructions for how to care for yourself at home.

The effects of CyberKnife treatment may take weeks or months to be seen. The prognosis depends on the condition being treated. Your provider will likely monitor your progress using imaging tests such as MRI and CT scans. PET scans and blood tests.

Stereotactic radiotherapy; SRT; Stereotactic body radiotherapy; SBRT; Fractionated stereotactic radiotherapy; SRS; CyberKnife; CyberKnife radiosurgery; Non-invasive neurosurgery; Brain tumor - CyberKnife; Brain cancer - CyberKnife; Brain metastases - CyberKnife; Parkinson - CyberKnife; Epilepsy - CyberKnife; Tremor - CyberKnife

Gregoire V, Lee N, Hamoir M, Yu Y. Radiation therapy and management of the cervical lymph nodes and malignant skull base tumors. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 117.

Linskey ME, Kuo JV. General and historical considerations of radiotherapy and radiosurgery. In: Winn HR, ed. Youmans and Winn Neurological Surgery. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 290.

Zeman EM, Schreiber EC, Tepper JE. Basics of radiation therapy. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 27.

Updated by: David Herold, MD, Radiation Oncologist in Jupiter, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.