External Beam Radiation Therapy (EBRT)


What is External Beam Radiation Therapy (EBRT)?

EBRT is the most common radiation treatment for cancer. It’s called external because machines outside the body aim high-energy x-rays (or beams) at cancer tumors. EBRT is used to treat a wide range of cancers, including brain, spine, lung, breast, prostate, bladder, liver and bone cancer.

EBRT can be used alone or in combination with other therapies to shrink tumors, prevent cancer cells from growing after surgery, relieve symptoms and help keep cancer from returning. Advanced technologies allow Mercy cancer specialists to precisely target tumors while sparing healthy tissues.

Types of EBRT 

Mercy offers advanced EBRT treatments and many of the latest-generation technologies to provide highly targeted and effective radiation therapy. Our specialists use several types of EBRT, depending on the tumor size and location, nearby organs and whether other cancer treatments are needed.

TomoTherapy delivers radiation on a machine that rotates around the body in an arc, using built-in imaging to target tumors from many angles.

IGRT uses detailed CT or MRI images taken before each radiation session to narrowly target treatment areas.

IMRT varies the intensity of radiation beams so that stronger doses reach specific tumor areas.

SRS and SBRT deliver precise, high-dose radiation in just a few sessions (up to five).

3D CRT uses image guidance to shape radiation beams to the contours of cancer tumors.

Proton therapy uses high-energy proton beams to deliver radiation with sub-millimeter precision, minimizing side effects.

EBRT:  What to Expect

EBRT is usually done on an outpatient basis in sessions that last just 15-30 minutes. Your overall treatment length (in weeks) depends on your cancer type, stage, and the form of EBRT you’re receiving. Treatments are painless and are carefully planned to minimize effects on healthy tissues and organs.


During planning sessions, your Mercy treatment team determines the type and dose of EBRT that’s right for you. You’ll have a CT scan to help pinpoint the treatment area. During a simulation session, your team identifies the best place to deliver radiation, and you may receive temporary markings on your body.


During treatment, you’ll be positioned on a table and asked to lie still. Depending on your cancer type, a breathing coordinator will help you breathe normally or hold your breath. Your radiation therapist will go into a control room to start treatment but will continue monitoring you. You can still communicate with the team if needed, so let them know if you feel uncomfortable. Receiving radiation takes only a few minutes, and you may hear the machine make noises during treatment.


After EBRT treatment, your Mercy cancer specialist may order imaging, bloodwork or other tests to check your progress and modify treatment if needed.

EBRT Side Effects & Risks

The most common side effects of EBRT are fatigue and skin changes at the treatment site, such as dryness, itching, peeling or blistering. Side effects usually go away a few months after treatment, but it’s possible they’ll become severe or won’t improve. Depending on the area of the body treated, other side effects may include:

  • Diarrhea
  • Hair loss at the treatment site
  • Inflammation or tenderness at the site
  • Mouth problems
  • Nausea and vomiting
  • Sexual changes
  • Swallowing difficulty
  • Urinary changes

Late side effects can appear months or years after treatment and vary by the area treated and radiation dose. These side effects may include infertility, joint problems, lymphedema, mouth problems and (rarely) new primary cancers. Talk with your Mercy cancer treatment team about potential side effects from EBRT and ways to manage them.

Deep Inspiration Breath-Hold

Learn how holding a deep breath during radiation therapy can help protect your heart.

Coordinated Radiation Oncology Care

At Mercy, your oncologist will plan, prescribe and supervise your care. But it’s our team approach that allows us to provide exceptional service and compassionate cancer care. Other team members may include physician assistants, registered radiation therapists, nurses, medical physicists, dosimetrists and other support professionals.

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