Stereotactic radiosurgery (SRS) is a type of radiation therapy used in the treatment of tumors, cancers, and other conditions. It uses precise beams to attack the DNA of affected cells in particular areas of the body, limiting the area that is exposed to radiation so that healthy cells can be avoided. With their DNA damaged, the diseased cells are unable to reproduce, and they shrink over time. Despite its name, stereotactic radiosurgery is nonsurgical: radiation beams are delivered from outside of the body, and no incisions are required. SRS can be done on the brain (cranial radiosurgery), the spine (spinal radiosurgery), and other areas of the body (stereotactic body radiation therapy, or SBRT).
SRS can be used alone or as a supplement to other treatments. Because it minimizes damage to healthy tissue, it is preferred over less specific radiation therapies when possible, such as conventional external beam radiation (EBRT), especially in sensitive regions like the brain. Whereas conventional EBRT would target the whole brain, cranial SRS could be performed with greater specificity, making it suitable for smaller tumors and those in difficult-to-reach locations.
In determining your treatment plan, your doctors will also need to consider the urgency of your condition. Radiation therapies take time before they are effective. Depending on what is being treated, it may be weeks (arteriovenous malformations, or tangled blood vessels), months (cancerous, or malignant, tumors), or even years (non-cancerous, or benign, tumors) before you experience the benefits from SRS. For situations that require more immediate care, open surgery may be the first option. SRS might then be performed to eliminate any remaining diseased cells.
SRS machines typically differ based on the type of beams they deliver. Two common brands of machines include the Gamma Knife and CyberKnife.
- Gamma Knife machines are usually used to deliver gamma rays to small brain tumors and other brain lesions, although they can also target the neck and head. Gamma Knife radiosurgery requires that you wear a large head frame during treatment. Treatment is completed in a single session, and multiple areas can be targeted in one sitting.
- CyberKnife radiosurgery can deliver X-rays to any part of the body, using a robotic arm, which allows this technique to accommodate for tumor or patient movement, such as breathing. You will receive your treatment lying down while the system moves around you. Treatment may occur in single or multiple sessions.
Cranial and spinal radiosurgery are usually completed in a single treatment session, while SBRT tends to require multiple. Each session can last anywhere from a few minutes to a few hours depending on the type of treatment and the target location. You may return home the same day that you receive your treatment and resume normal activities within 2-3 days.