Stereotactic body radiotherapy (SBRT) is a type of radiation therapy that uses many beams of energy. The beams are carefully targeted to focus on growths of cells, which are called tumors, anywhere in the body.

SBRT is used to treat tumors in the lungs, spine, liver, neck, lymph nodes or other soft tissues.

SBRT is sometimes called stereotactic ablative radiotherapy (SABR). When used on the brain, it is often called stereotactic radiosurgery (SRS).

SBRT uses 3D or 4D imaging and highly focused radiation beams to send high doses of radiation to the area to be treated. This results in the least amount of damage to the healthy tissues around the area.

Like other forms of radiation therapy, stereotactic body radiotherapy works by hurting the DNA inside the tumor cells. The damage from the radiation stops the cells from making more tumor cells. This causes tumors to shrink.

Stereotactic body radiotherapy usually takes 1 to 5 sessions.

Types of stereotactic body radiotherapy

Types of SBRT include:

• Linear accelerator, also known as LINAC. LINAC machines use X-rays, also known as photons, to treat tumors.
• Proton beam, also called charged particle. This newer type of stereotactic radiotherapy uses protons to treat tumors over several sessions. Proton beam radiotherapy might be used to treat tumors in parts of the body that have already had radiation therapy. Or they can treat tumors that are near vital organs.

Why it's done

Stereotactic body radiotherapy is used to treat growths of cells, which are called tumors. SBRT is used to treat tumors in the lungs, spine, liver, neck, lymph nodes, soft tissues and other parts of the body. SBRT is used to treat cancerous tumors and tumors that aren't cancerous, which are called benign tumors.

Risks

Stereotactic body radiotherapy treatment has a risk of side effects and complications.

Early side effects

Side effects that happen soon after treatment are usually short term. They can include:

• Fatigue. Extreme tiredness can occur for the first few days after SBRT.
• Swelling. Swelling at or near the treatment site can cause symptoms such as a short-term increase in pain. A health care provider might prescribe medicines to prevent or treat these symptoms.
• Nausea or vomiting. Treatment for a tumor near the bowel or liver might cause these symptoms for a short time.
• Skin changes. Skin in the treatment area can become irritated, itchy or dry.

Late side effects

Rarely, some people get side effects months or even years after treatment. These might include:

• Weakened bones that can break.
• Changes in the bowel or bladder.
• Changes in the lungs.
• Changes in the spinal cord.
• Swollen arms and legs, also known as lymphedema.
• A new cancer.

How you prepare

Preparation for stereotactic body radiotherapy varies depending on the condition and body area being treated.

Food and medications

• You might be asked not to eat or drink anything 2 to 3 hours before the procedure.
• Talk to your health care provider about whether you can take your regular medicines the night before or morning of the procedure.

Clothing and personal items

Wear comfortable, loose clothing.

You might be asked not to wear:

• Jewelry.
• Eyeglasses.
• Contact lenses.
• Makeup.
• Nail polish.
• Dentures.
• Wigs or hairpieces.

Medical devices

Tell your health care team if you have medical devices inside your body. These might include a pacemaker, artificial heart valve, aneurysm clips, neurostimulators or stents.

What you can expect

Stereotactic body radiotherapy is usually an outpatient procedure. This means you likely won't need to stay in the hospital after treatment.

Each treatment takes up to an hour. It's usually not necessary to have a family member or friend come with you to treatment. Ask a member of your health care team if you'll need to have someone with you.

All types of stereotactic body radiotherapy work in a similar way. The machine focuses beams of radiation on the target. Each beam does little damage to the tissues it passes through. The spot where all the beams meet gets a high dose of radiation.

The high dose of radiation causes tumors to shrink. Over time, the radiation causes blood vessels to close, robbing tumors of their blood supply.

Before the procedure

Your health care team takes several steps before stereotactic body radiotherapy. Steps might include:

• Positioning. To target treatment exactly, the person getting treated must remain completely still. Your health care team will find the best position for your body. Often this involves using custom devices to hold you in place and keep you comfortable.
• Marking. Markers help target treatment. Often, tattoos on the skin keep the area marked for repeated treatments. Sometimes it's necessary to place a small metal marker, known as a fiducial marker, in or near the tumor. The fiducial marker is about the size of a grain of rice.
• Imaging. Once you're in place, imaging scans get information about your tumor, including location, size and shape. A scan also can show how the tumor moves while you breathe. Sometimes, the information gathered might show that you might need to hold your breath for 10 to 30 seconds at a time during treatment to keep the tumor still.
• Planning. Using the imaging scans and specialized software, your health care team plans the best approach to treatment.

During the procedure

Children might receive medicine to put them in a sleep-like state during the procedure. Adults typically don't need this medicine. If you feel very nervous about your treatment, you might receive medicine to help you relax.

SBRT isn't painful. You'll be able to talk to a member of your health care team during the procedure.

After the procedure

After the procedure, you can expect the following:

• If you have symptoms such as a temporary increase in pain or nausea, ask for medicines to treat them.
• You'll be able to eat and drink after the procedure.
• Usually, you can go home the same day.
• You can usually get back to regular activities within a day or two.

Results

The effects of stereotactic body radiotherapy treatment happen over time. Stereotactic body radiotherapy might result in the following:

• Tumors that aren't cancerous, which are called benign tumors, might take 18 months to 2 years to shrink. The main goal of treatment for benign tumors is to keep the tumor from growing.
• Cancerous tumors might shrink faster, maybe within a few months.

You may have follow-up exams and tests to monitor your progress after stereotactic body radiotherapy.