Overview

Stereotactic radiosurgery (SRS) is a type of radiotherapy. When it's performed on the body rather than the brain, this procedure is sometimes called stereotactic body radiotherapy (SBRT) or stereotactic ablative radiotherapy (SABR).

The procedure uses many precisely focused radiation beams to treat tumors and other problems all over the body. SBRT is used to treat tumors in the lungs, spine, liver, neck, lymph node or other soft tissues.

Because there's no incision, SBRT isn't a traditional type of surgery. Instead, SBRT uses 3D imaging to target high doses of radiation to the affected area. This means there's very little damage to the surrounding healthy tissue. Like other forms of radiation, stereotactic radiosurgery works by damaging the DNA of the targeted cells. Then, the affected cells can't reproduce, which causes tumors to shrink.

Body radiotherapy usually involves between one to five sessions.

Types of stereotactic radiosurgery

Doctors use two types of technology to deliver radiation during stereotactic radiosurgery.

• Linear accelerator (LINAC) machines use X-rays (photons) to treat cancerous and noncancerous abnormalities in the brain and other parts of the body. LINAC machines are also known by the brand name of the manufacturer, such as CyberKnife and TrueBeam. These machines can perform SRS in a single session or over two to five sessions for larger tumors (fractionated stereotactic radiotherapy).
• Proton beam (charged particle) is the newest type of stereotactic radiotherapy and is available in only a few research centers in the U.S., although the number of centers offering proton beam therapy has greatly increased in the last few years. It can use fractionated stereotactic radiotherapy to treat body tumors over several sessions. Proton beam SBRT may be used to treat tumors in parts of the body that have previously received radiation therapy, or those that are near critical organs.

How it works

All types of stereotactic radiosurgery and radiotherapy work in a similar manner.

The specialized equipment focuses beams of radiation on a tumor or other target. Each beam has very little effect on the tissue it passes through, but a targeted dose of radiation is delivered to the site where all the beams intersect.

The high dose of radiation delivered to the affected area causes tumors to shrink and blood vessels to close off over time following treatment, robbing the tumor of its blood supply.

The precision of stereotactic radiosurgery means there's minimal damage to the healthy surrounding tissues. In most cases, radiotherapy has a lower risk of side effects compared with other types of traditional surgery or radiation therapy.