Radiation therapy for prostate cancer – External beam radiation therapy

During external beam radiation therapy for prostate cancer (EBRT), radiation is delivered from an outside source that targets the prostate gland.

It is a painless procedure that is similar to getting a typical x-ray.

Men usually receive radiation therapy for prostate cancer 5 days a week for 7 to 9 weeks.

The set-up time each day often takes longer than the actual treatment, which should only take a few minutes.

Testing first

The first step is a series of tests that are used to pinpoint the areas that need to be treated. This helps to minimize damage to healthy tissues. These tests may include:

  • MRIs
  • CT scans
  • X-rays of the pelvis

Once these areas are located, your man may receive small ink spots on his skin so the technicians will know where to aim the treatment.  Don’t worry.  They are barely noticeable.

CT-scan guided radiation therapy


Some medical centers now do a CT scan every day for the first week or two to get a baseline of how much a man’s prostate gland moves in position from day to day. Then the CT scan is used at set intervals to help ensure accuracy.

This is a good question to ask about prior to radiation therapy for prostate cancer.


There are three commonly used techniques

Three-dimensional conformal radiation therapy for prostate cancer:

  • Computers determine the exact location of the prostate and where high-energy x-rays will be delivered
  • May involve the use of a plastic body mold (like a body cast), which helps a man stay in one position
  • Appears to be as effective as standard EBRT with lower side effects

Intensity modulated radiation therapy:

  • A computer-guided machine moves a man around as radiation is delivered from different angles
  • Amount delivered can be increased or decreased, depending upon the area of delivery
  • Used routinely in many major hospitals and cancer centers

Newer machines have built-in imaging scanners, a technological advancement called image-guided radiation therapy.  This allows pictures to be taken of the prostate so that positioning adjustments can be made prior to receiving radiation.

Another type of intensity modulated radiation therapy for localized prostate cancer is called:

  • Stereotactic radiotherapy (when multiple treatments are given)
  • Or stereotactic radiosurgery (when only one treatment is provided)

A man’s head is held in place by a metal frame or cage. It is also used to treat cancer that has spread to the brain.

Conformal proton beam radiation therapy:

  • Uses proton beams that, unlike x-rays, do not release energy before and after they reach the desired area of the prostate
  • It is believed that this may cause less damage to healthy tissues.

Is it really better than traditional radiation?  Read more.

Potential side effects

After radiation therapy for prostate cancer, some men may experience bowel problems, such as:

  • Diarrhea
  • Blood in stool
  • Loose stools
  • Rectal pain
  • Blood in urine
  • Frequent urination
  • Burning while urinating

There is also a chance of urinary incontinence and impotence after radiation therapy for prostate cancer. These problems may develop over time. Other factors may influence the development of these side effects, including:

  • Age
  • Previous urinary or erectile problems

Changes over time

You should know that after several years:

  • The impotence rate for radiation for prostate cancer is similar to that of surgery
  • Incontinence may be less common, but the risk increases each year for a few years

Your loved one may feel tired, especially toward the end of radiation therapy for prostate cancer. This tiredness may last for several months after treatment has ended.  Some men say that exercising helps with fatigue, but always check with the doctor.


Rarely, men may develop scarring or narrowing of the tube that carries urine from the bladder out of a man’s body (called a urethral stricture), which can cause urination problems that require treatment to reopen the urethra.


Internal radiation therapy
Return to treatments


The American Cancer Society. Prostate Cancer. http://www.cancer.org. Accessed March 17, 2015.

US TOO International, Inc. Pathways for new prostate cancer patients. http://www.ustoo.com. Accessed September 1, 2008.

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