Stereotactic Body Radiation Therapy (SBRT)

What is SBRT?

Stereotactic body radiation therapy (SBRT) is a type of cancer treatment that precisely delivers radiation to tumors. This helps spare the surrounding normal tissue.

You may also hear it called stereotactic ablative radiotherapy (SABR), or, more commonly, by the brand name of the machine used.

There are two different types of SBRT technology used for radiation treatment:

Linear accelerator (LINAC) – uses X-rays to treat tumors in the body and brain. Treatment with LINAC machines typically consists of 1-5 sessions. You might hear them called CyberKnife or TrueBeam, which are brand names.

This is the type of machine used at the San Antonio Cancer Center.

Proton beam – is a less common technology but can be used close to critical organs or on parts of the body that have previously had radiation therapy. Treatment typically takes several sessions.


How does it work?

In general, radiation therapy stops cancer cells from being able to reproduce. The cancer cells then die, and the tumor shrinks. SBRT is an external type of radiation that directs radiation beams with incredible precision at a tumor. The beams don’t harm the tissue they pass through on their way to the tumor, but when all the beams intersect on the tumor, they deliver a targeted dose of radiation. The radiation shrinks the tumor and cuts off its blood supply.

It’s used to treat tumors in the:

  • Abdomen
  • Brain
  • Liver
  • Lungs
  • Lymph nodes
  • Neck
  • Pancreas
  • Prostate
  • Spine
  • Other soft tissues

It may also be a treatment option for tumors that can’t be treated with other types of radiation.


Prior to your procedure, you’ll have a simulation appointment that will be like a dress rehearsal for the procedure. You may use a special bed, mask, or other molds or casts to support or protect you during the procedure.

You may have a CT scan, MRI, or X-rays to show precisely where your tumor is. Your doctor may also mark your skin or place small, gold markers near the tumor to help focus the radiation beams.

The night before the procedure, you’ll be instructed not to eat or drink after midnight.

During the procedure:

  1. You may be given medication for anxiety, if needed.
  2. If you had a special bed fitted for your procedure or a mask to protect your face and neck, you’ll use those during treatment.
  3. Your radiologist will use a CT scanner to see your tumor. Then, the SBRT machine will be used to deliver the radiation beams to the tumor.
  4. You’ll probably go home the same day and will be able to return to normal activities in a day or two.

The treatment will take less than an hour and is painless. Depending on where your tumor is located and how large it is, you may need 1-5 sessions.

After your procedure, it’s essential to:

  • Avoid the sun
  • Eat healthy foods
  • Rest
  • Take care of your skin at the site of the radiation. Ask about lotions to help with discomfort or itchiness.

Cancerous tumors tend to shrink quickly after treatment, but non-cancerous tumors may take as long as two years to shrink.

Side Effects

SBRT has fewer side effects than other types of radiation therapy or surgery. After your procedure, you may experience side effects like:

  • Fatigue
  • Itchiness at the site of the radiation
  • Nausea or vomiting (tumors near the bowel or liver)
  • Redness on the site of the radiation
  • Swelling at the location of the radiation
  • Others, depending on the location of the tumor

It’s possible, but rare, to have side effects months after treatment. When it happens, symptoms vary by body site but can include:

  • Brittle, weakened bones
  • Bowel changes
  • Lung changes
  • Lymphedema (swollen arms and legs)
  • Secondary cancer
  • Spinal cord changes
Quick Facts
  • Precise radiation therapy decreases side effects

  • Used to treat many different types of cancer

  • Fewer treatments needed than other therapies