Radiation for Prostate Cancer

Radiation therapy may be a treatment option for certain men with prostate cancer.

Aside from surgery to remove the prostate, it is the only way to eliminate prostate cancer.  The San Antonio Cancer Center is an entire facility dedicated to radiation therapy for cancer treatment.  Although we treat many types of cancers, we specialize in radiation for prostate cancer.

Types of Radiation Therapy for Prostate Cancer

The San Antonio Cancer Center uses the most advanced and precise methods of radiation therapy for prostate cancer.

External Beam Radiation Therapy (EBRT) – EBRT uses beams of radiation from a machine outside the body to treat the prostate. It’s used to try to cure early-stage cancers or relieve symptoms such as bone pain if cancer has spread to a specific area in a bone.

Intensity-modulated radiation therapy (IMRT) – IMRT is an advanced type of EBRT. It uses a computer-driven machine that rotates around the patient to deliver targeted radiation. By modulating the intensity (changing the strength) of the radiation beam, your therapy team is able to limit exposure to nearby healthy tissue. It also helps deliver higher doses of radiation directly to the cancer.

Image-guided radiation therapy (IGRT) – IGRT is an enhancement to IMRT that incorporates imaging techniques before each treatment session. There are different forms of IGRT. Cone Beam CT can visualize any soft tissue and On-Board Imaging can visualize bone. At our center, all IMRT treatments incorporate the use of the IGRT technology.

Linear Accelerator at San Antonio Cancer Center

Linear Accelerator at San Antonio Cancer Center

To treat prostate cancer, we utilize 4D Imaging with Cone Beam CT – Before each treatment, your radiation therapist will scan the treatment area with a Cone Beam CT scanner. This allows your treatment team to see the bladder, prostate, and rectum immediately before your treatment.

Superimposing these images with the treatment plan allows for the most precise targeting. Even small movements of your internal organs can cause treatment to be less accurate. This is why we make sure any necessary adjustments are made before treatment.

Note: Not all IMRT/Prostate Cancer Treatment facilities use these advanced imaging techniques. Some treatment centers may use older technology and metallic implants. This type of imaging does not show soft-tissue like the prostate, bladder, or rectum.

The use of implants is more invasive and may be less precise due to settling or movement of the implants over time. It can also cause treatment delays due to a waiting period between inserting the implants and treatment.

Meet Your Radiation Therapy Team

Your radiation therapy team is a group of healthcare providers.  Their goal is to make your treatment as effective and comfortable as possible. This team includes:

Radiation Oncologist – Dr. Selva is a radiation oncologist and medical director at the San Antonio Cancer Center. He treats more prostate cancer patients than any radiation oncologist in the city.  This incredible expertise helps you get the best results. As the radiation oncologist, he will:

  • Lead the radiation therapy team
  • Create your customized radiation therapy regimen, which includes the amount of radiation and how the treatment will be delivered.
  • Closely monitor your progress throughout treatment.
  • Direct any care needed if you experience side effects from radiation therapy.

Radiation Physicist – The radiation physicist makes sure the machine that delivers radiation is working properly.  The machine is a linear accelerator. It moves around you to deliver precise doses of radiation.

Radiation Nurse – The radiation nurse will assist you through your treatment process and interact with the rest of your radiation team.

Radiation Therapist – The radiation therapist works with you during each treatment. He or she will make sure you have the proper position for treatment.  They will also operate the linear accelerator to deliver the radiation.

Dosimetrist –  The dosimetrist is a professional that calculates the proper radiation doses

The Patient – You are the most important part of the team.  You help ensure success by asking questions, voicing concerns, and arriving at each appointment on time. It’s also important to speak up if you’re experiencing any pain or side effects from radiation.  Your team may be able to help.

The Treatment Process

The treatment process usually begins with your urologist.  Your urologist may recommend that you consider radiation therapy for prostate cancer.  If so, an appointment with Dr. Michael Selva, Radiation Oncologist is the next step.

Dr. Selva also sees many second-opinion patients from other practices.  He also visits with patients looking for an alternative treatment facility.


At your first visit, you’ll meet with the radiation oncologist, Dr. Michael Selva.  Dr. Selva will review your medical history, pathology reports, and conduct a physical exam.  He takes plenty of time (usually an hour and a half) to answer your questions.

If you are ready to move forward with treatment, our team will help you set an appointment for simulation.

Simulation (Positioning)

At this appointment, your medical team determines the exact position you should be in for treatment. To help maintain your position during treatment, we create a custom mold of your body. You will use this mold to rest in each time you receive treatment. Prostate cancer patients will have a mold that holds the torso in the proper position.

For further precision, your team uses positioning lasers and marks on your body. These marks need to be consistent, so your team will make tiny tattoo dots on your skin. Patients need three, freckle-sized marks. These marks will be laser aligned before each treatment.
Once your treatment position is complete, the medical team will conduct a CT scan. This helps gather even more data to create your personal treatment plan.

The simulation/positioning appointment typically takes an hour to complete.

CT Scan at San Antonio Cancer Center

Monitoring CT Scan

Treatment Planning

Using all the information gathered thus far, your radiation therapy team will design the best IMRT treatment plan for you. This process usually takes 3-4 days.

Plan Verification

When your treatment plan is ready, the team performs a simulated treatment on a “phantom” patient. After that, you’ll return for a final planning appointment. At this appointment, the team will verify the treatment plan matches your anatomy. They will also fine tune your position if necessary.

Treatment Delivery

Treatment can start as soon as your plan is complete. Our team will work with you to select a regular treatment time that fits your schedule.

Treatment visits usually take a total of 30 minutes. Most of this time is undressing, dressing, and positioning.

The actual delivery of radiation takes only a few moments. The number of treatment sessions required varies based on the type of cancer you have and your plan.

For prostate cancer patients, treatments are usually given once a day, 5 days a week, for 9 weeks. This is a total of 45 treatments.

Patients who have had their prostate removed usually have 8 weeks of treatment. This is a total of 40 treatments.

Monitoring & Follow-Up Care

Once a week, you’ll meet with your nurse and Dr. Selva. They check your weight, vital signs, and symptoms. They will also guide you through any difficulties you may encounter.

When you complete your entire treatment plan, you will meet with Dr. Selva. He will review the treatment’s effectiveness and discuss your long-term prognosis.

After these visits, patients usually return to their urologist for routine cancer monitoring.

On Treatment Day

Before You Arrive

For the best results, you should have a full bladder for your treatment. We recommend you drink 20 oz. of water approximately 30 minutes before your treatment time. Your radiation therapy team will provide you with a 20 oz. water bottle to take home.

When You Arrive

Before each treatment, you will first change into a hospital gown or robe. We recommend you wear clothes that are easy to take on and off.

Before Treatment

Once you’re in the treatment room, you will lie on the treatment table. The radiation therapist will make sure your position is correct. They will do this by lining up the marks on your skin made during your simulation appointment.


The radiation treatment will only take 1 to 5 minutes. You will be in the treatment room approximately 15 minutes total. The radiation process is painless; like getting an x-ray. You will not see or smell the radiation, but you will hear noise coming from the machine.

The therapist will exit the room before treatment begins. They will control the machine from another area nearby the treatment room. Your therapist can see you, hear you, and talk to you through an intercom system. You may breathe normally, but it’s important to hold still so the treatment is precise.

If you feel sick or uncomfortable tell your therapist right away. The therapist can pause treatment at any time.

The machine is large and makes noise as it moves around your body. This allows treatment of the prostate from different angles. It can be intimidating at first. If you have concerns or questions about anything that happens in the treatment room, talk to your radiation therapist.

Diet Recommendations

We recommend you stay away from caffeine and alcohol before your treatment. Treatment is best with a full bladder, and both can cause increased passing of urine.

Possible Side Effects of Radiation Treatment

There are possible side effects associated with radiation therapy. Some people may not experience any side effects.  Others may experience mild or bothersome side effects.

Some side effects may only last a short period of time, and others may last longer or forever. Side effects may occur at the time of treatment or could develop months after treatment.

Most side effects are manageable by your radiation team and last only a short time. Before starting treatment, your doctor will discuss possible side effects and their duration.

Because we use advanced targeting technology, the probability of side effects is lower.

Possible side effects include:

Bowel Issues – Because radiation treatment is so close to the rectum, it could cause irritation. This irritation could cause soreness, blood in your stool, or rectal leakage. Most of the time these issues are temporary, but in rare cases, normal bowel function does not return. Because patients use a rectal balloon during each treatment, the likelihood of rectal issues is lower.

Urinary Issues – Radiation can cause irritation to the bladder. This can cause urinary frequency, urgency, and a burning sensation. If these problems occur, they generally go away after time.

Fatigue – You may feel more tired than usual during and after your IMRT treatment. It’s important to get plenty of rest and have a regular sleep schedule.  Drinking water and eating a healthy diet is also important.  Following these recommendations can improve your energy level.

Keeping your activity level up will result in less fatigue and feeling better.

Keeping your activity level up will result in less fatigue and you will feel better overall.


Does Dr. Selva see second opinion patients considering radiation for prostate cancer?

Yes, Dr. Selva sees patients for second opinions for radiation therapy. It’s important to feel comfortable with your radiation oncologist and their team.

Will radiation therapy make me radioactive or dangerous to other people?

No, radiation therapy will not make you radioactive.  Radiation therapy in no way will limit your contact with other people including hugging, kissing, and intercourse.

Can I have sex during or after IMRT treatment?

Yes, however, treatment may temporarily lower your desire to have sex.

How long does each treatment take from the time I arrive to the time I leave?

Our goal is to have you in and out within 30 minutes.

Why do I need so many daily treatments?

Delivering small amounts of radiation over time can help prevent bothersome side effects. Delivering more radiation over a shorter time could cause damage to nearby tissue.

Quick Facts
  • Common treatment for prostate cancer

  • Uses radiation to kill cancer cells

Radiation for Prostate Cancer Doctors
Michael Selva, MD