Intensity-Modulated Radiation Therapy to the Prostate

This information will help you prepare for intensity-modulated radiation therapy to the prostate, including what to expect before, during, and after your treatment.

Prostate cancer is the most common cancer in men in the United States. Tests used to find early prostate cancer are:

  • A PSA blood test
  • A digital rectal exam
  • An ultrasound of the prostate
  • A prostate biopsy

Early prostate cancer can be cured with surgery or radiation. There are 2 types of radiation therapy used to treat prostate cancer. These can be used alone or in combination. Your doctor will recommend what is best for you:

  • External beam radiation: the radiation comes from a machine and is directed as a beam to the area to be treated.
  • Internal radiation: the source of radiation is put inside the body.

Intensity-modulated radiation therapy (IMRT) uses a computer to plan and give the external beam radiation treatment. It is more targeted than standard external beam therapy. The radiation machine moves around the body so the beams can be aimed from many angles. In addition, the shape of the beam changes while the treatment is being given. This modulates or varies the intensity of the beam. The cancer gets a high dose of radiation and the nearby normal tissues get a very low dose.

You may also receive hormonal therapy if:

  • You have a large prostate gland
  • The cancer is aggressive

The hormonal therapy will decrease the amount of male hormone in the body. That will shrink the gland and stop the cancer from growing. A smaller prostate will allow us to use a smaller beam of radiation. This may mean fewer side effects. If you have an aggressive type of cancer, lowering your hormone level may help to make treatment more effective. In this case, the therapy is usually given during radiation. It may be continued after your treatment is done. If you will get hormonal therapy, your doctor or nurse will give you more information about it.

Before you begin treatment, you will go through simulation and treatment planning. These are done to ensure that:

  • The treatment site is mapped out.
  • You get the right dose of radiation.
  • The dose to nearby tissue is small.

Your simulation will take 2 to 4 hours. Both male and female therapists will do your simulation.

Preparing for Your Simulation

Gold seed placement

One to 2 weeks before your simulation, your doctor may request that you have 3 gold seeds placed in your prostate. These can be seen on x-ray and can help improve the accuracy of the radiation therapy. The gold seeds are put in by a urologist. His or her nurse will call you to review the procedure. If you are having combination therapy with radioactive seed implant and IMRT, the gold seeds will be placed during the implant procedure. If you had a prostatectomy, you will not need the gold seeds.

Bowel preparation

During your simulation, your bowel must be empty of stool. You will need to do a bowel preparation the day before your simulation.

You will need to purchase the following supplies before your simulation:

  • One 5 mg tablet of bisacodyl (Dulcolax®). These are usually sold as a box of 10 tablets.
  • One-gallon (128 ounces) bottle of NuLYTELY® bowel preparation with flavor packs (cherry, lemon-lime, orange, and pineapple). Your doctor will give you a prescription for this.

If you take medication for diabetes, ask your doctor for instructions on the bowel preparation.

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The Day Before Your Simulation

  • Take your usual medications.
  • Eat breakfast as usual, but try to finish your breakfast by 10:00 am.
  • After breakfast start a clear liquid diet as described below.
Food Category You May Have You May NOT Have


  • Clear broth or bouillon
  • Clear consommé

Any other soups

Sweets and Desserts

  • Gelatin
  • Flavored ices
  • Honey, sugar, sugar substitutes
  • Hard candy

Any other sweets or desserts


  • Water
  • Clear fruit juices, such as apple, cranberry, or white grape, Kool-Aid®
  • Gatorade®
  • Black coffee or tea (in limited amounts, no more than 2 cups)
  • Juice with pulp or nectars
  • Carbonated drinks or soda, such as ginger ale, 7-Up®, Sprite®, seltzer, cola
  • Alcoholic beverages
  • Milk or cream
  • Diet liquids

Prepare your NuLYTELY® bowel preparation solution

On the morning of the day before your procedure, add lukewarm drinking water to the NuLYTELY®, filling it to the top of the line on the bottle. Add a flavor pack, if you choose. Use only a flavor pack that came with the NuLYTELY®. With the cap on, shake the bottle until the powder is dissolved. The mixture will be clear, even if you used a flavor pack. Place the bottle in the refrigerator to chill the solution, as patients have told us it tastes better cold. Do not mix the NuLYTELY® earlier than the morning before your procedure.

Drink only half (64 ounces) of the NuLYTELY® . Throw out the other half.

At 1:00 pm on the day before your procedure, take 1 bisacodyl tablet by mouth with a glass of water.

At 3:00 pm on the day before your procedure, start drinking the NuLYTELY® .  Drink an 8-ounce glass of the solution every 15 minutes, until you finish 64 ounces of the solution. Then, continue drinking clear liquids.

NuLYTELY® will cause frequent bowel movements, so be sure to be near a bathroom when you start drinking it. To help prevent irritation, you can apply petroleum jelly (Vaseline®) or A&D® ointment to the skin around to your anus after every bowel movement.

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The Day of Your Simulation

  • Continue following the clear liquid diet. After your simulation, you can resume your regular diet.
  • Take your usual medications. If you take medications for diabetes, ask the doctor who prescribes it what to do the day of your simulation.
  • During the simulation, you will stay in one position for a long time. If you think this will be hard for you, take acetaminophen (Tylenol®) or your usual pain medication 1 hour before your appointment. Some people experience anxiety during the procedure. If you think you will feel anxious, ask your doctor about medication that may be helpful.

During Your simulation

When you arrive for your appointment, your radiation therapist will greet you and take a photograph of your face. This picture will be used to identify you throughout your treatment.

Your therapist will then explain the procedure to you. If you have not already signed a consent form, your doctor will review it with you, and ask for your signature. Your therapists will not begin the simulation without your permission.

You will get undressed and change into a gown. You can keep your shoes on.

You will need to drink about 1 cup of barium liquid. This helps us see your small intestine on the x-rays that will be taken later. You may be asked to drink 2 cups of water before the simulation begins. This is to fill your bladder. You may need to have a catheter placed into your bladder during the procedure. The catheter will be removed before you go home.

Your therapist will walk you to the machine and help you lie on the table. Although the table will have a sheet on it, it is hard and has no cushion. If you haven’t taken pain medication and think you may need it, tell your therapists before your simulation begins. Also, the room is usually cool. If you feel uncomfortable at any time, let your therapists know.

Throughout your simulation, you will feel the table move to different positions. The lights in the room will turn on and off and you will see red laser lights on each wall. Your therapists use these laser lights as a guide when they position you on the table. Do not look directly into the red beam because it may hurt your eyes.

Although your therapists will walk in and out of the room during your simulation, there will always be someone who can see and hear you. You will hear your therapists speaking to each other as they work. They will explain what they are doing, but please do not speak once they begin because it may change your position. However, if you are uncomfortable or need assistance, tell your therapists. To help pass the time, your therapists can play a CD for you. You can bring one of your own from home, if you wish.

Positioning (mold)

While you are lying on the table, a mold will be made of your lower body. Your therapists will place a warm, wet sheet of plastic over your lower hips and thigh areas. They will press on it to shape it to fit around your body. As the mold cools, it hardens. This procedure takes about 15 minutes.

During your simulation, and every day of your treatment, this mold will be placed over you. It will be attached to the table on which you are lying. It helps ensure that you are in the correct position each time you receive your treatment.

X-ray images

X-ray images will be taken of the area to be treated. If you had gold seeds placed, they will be seen on these. The images are taken on a specialized computed tomography (CT) scan machine or in the Department of Radiology. These CT scans are not used to diagnose your cancer. They are used to map out your treatment plan.

Before the CT scan is taken, a small rubber catheter will be inserted into your rectum. Air will be injected into the catheter to help us see your rectum on the scans.

You will hear the machines as they are turned on and off. Even if the noise seems loud, your therapists will be able to hear you if you need to speak with them.

The x-ray images take about 45 minutes.

Skin markings (tattoos)

Your therapists will draw on your skin with a felt marker. Then, they will make about 6 permanent skin markings, called tattoos, with a sterile needle and a drop of ink. The sensation of getting a tattoo feels like a pinprick. The tattoo marks are no bigger than the head of a pin. You can wash the felt markings off after your simulation. The tattoos are permanent and will not wash off. If you’re concerned about receiving tattoos as part of your radiation treatment, talk with your doctor.

After the tattoos are made, your therapists will take several photographs of you in your simulation position. The photographs and tattoo marks will be used to position you correctly on the table each day of your treatment.

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After Your Simulation

Treatment planning

At the end of your simulation, we will schedule you for your set-up procedure. This is the final appointment before your treatment begins. You will begin your treatment within several days after your set-up procedure.

During the time between your simulation and your set-up procedure, your radiation oncologist will work with a team to plan your treatment. They will use the images taken during your simulation to plan the angles and shapes of your radiation beams. They will also determine the dose of radiation that you will receive. These details are carefully planned and checked. This process takes 2 to 3 weeks.

Your treatment plan is based on your body shape and size at the time of your simulation. Try to keep your weight within 5 to 10 pounds of your usual weight to ensure that the plan remains accurate.

Treatment scheduling

At the end of your simulation, your therapist will ask you what time of day you would like to have your treatments. We will try to give you the time you like. However, we need a 2-hour window because the time you prefer may not be open. We will move you to that time slot once it opens up. Please know that we will do our best to give you the appointment time you want as soon as we can.

Radiation treatments are given daily, Monday through Friday, for 8 to 10 weeks. You will be in the department about 60 to 90 minutes each day. If additional time is needed due to unforeseen circumstances, your radiation oncologist will tell you. Make sure you come to every appointment because treatment may not be as effective if you skip or miss appointments. If you need to change your schedule for any reason, please speak with your therapists.

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Set-up Procedure

Before your first treatment, you will have a set-up procedure. This procedure usually takes about 1 hour. If pain or anxiety medication was helpful during your simulation, you may want to take it before this procedure.

When you come for your set-up procedure, you will be shown the dressing room and asked to change into a gown. Your therapists will bring you to the room where you will receive your treatment each day. They will position you on the table. You will lie exactly as you did the day of your simulation.

X-rays of each of the radiation beams (beam films) will be taken to make sure that your position is correct and that the area being treated is exactly what your radiation oncologist wants. Sometimes adjustments are made at this time. If you had gold seeds placed, these can be seen on the x-rays and will help us position you correctly. The beam films will be repeated throughout your treatment. They are used to make sure you are in the right position and are getting treated in the right place. They are not used to see how your tumor responds to the treatment.

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During Your Treatment

You will be in the treatment room for 15 to 30 minutes. Most of the time will be spent positioning you. The actual treatment takes 5 to 10 minutes.

After you check in at the reception desk, have a seat in the waiting room. When they are ready for you, your therapists will ask you to undress from the waist down and change into a gown. You can keep your shoes on during the treatment.

Some people will need to have a full bladder for their treatment. If your doctor tells you this is needed, your therapist will tell you how much water to drink and when to begin drinking it.

Your therapists will position you as you were on the day of your set-up procedure. Your mold will be placed over you during this procedure and each of your treatments.

Once you are properly positioned, your therapists will leave the room, close the door, and begin the treatment. If you had gold seeds placed, x-rays will be taken daily. Your radiation oncologist may use these to make adjustments to your treatment.

With IMRT, the beams are shaped by many small leaves of tungsten (a type of metal) sitting at the opening of the treatment machine. The computer will move the leaves into different positions to block the radiation. The radiation that passes through the opening between the leaves creates the beam that is directed toward your body. The leaves move while the beam is passing through. This varies the intensity of the beam and ensures that you receive the exact doses prescribed by your radiation oncologist. You will not see or feel the radiation, although you may hear the machine as it moves around you and is turned on and off.

Although you are alone during your treatment, your therapists can see you on a monitor and hear you through an intercom at all times. Breathe normally during your treatment, but do not move. If you are very uncomfortable and need help, speak to your therapists. They can turn off the machine and come in to see you at any time, if necessary.

Weekly visits during treatment

Your radiation oncologist and radiation nurse will see you each week to evaluate your response to treatment. This visit will be before or after your treatments each ________________. You should plan on being in the department about 1 extra hour on those days. During these visits, you should ask questions and discuss any concerns you have. If you need to speak with your radiation oncologist or radiation nurse any time in between these weekly visits, ask the support staff or therapists to contact them when you come in for treatment.

You may take a daily multivitamin during treatment if you want. It should not exceed the recommended daily amount of any vitamin or mineral. Do not take any other vitamins or nutritional or herbal supplements unless your doctor approves them.

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Side Effects

Some people develop side effects from treatment. The type and severity of side effects varies from person to person. Below are the most common side effects of radiation therapy to the prostate. You may have all, some, or none of these.

Urinary changes

Your prostate gland may swell and the lining of your bladder may become irritated during treatment. About 2 weeks after starting treatment you may have:

  • Difficulty starting to urinate
  • Increased frequency of urination
  • Frequent need to urinate at night
  • Sudden urge to urinate
  • Burning with urination

Below are guidelines to help you manage these symptoms.

  • Drink 6 to 8 glasses of water throughout the day.
  • Decrease your intake of liquids after 8:00 pm.
  • Avoid foods and beverages that may irritate the bladder. Examples are:
    • Caffeine
    • Alcohol
    • Spices
    • Tobacco
  • Tell your doctor or nurse know if you have any urinary changes. Medication can be prescribed to help.

Bowel Changes

The wall of the rectum may become irritated. About 2 weeks after starting treatment you may have:

  • More frequent and softer bowel movements
  • Worsening of hemorrhoidal symptoms
  • Rectal discomfort
  • Mucous discharge
  • A small amount of rectal bleeding
  • Increased gas
  • An increased urge to have a bowel movement

These symptoms are usually mild. When you begin treatment, there are no restrictions on your diet. If you develop any of these symptoms, talk with your nurse about how you can modify your diet to reduce them. If you are still uncomfortable, let your doctor or nurse know. Medication can be prescribed to help.

Sexual health

  • There is nothing radioactive inside your body. You cannot pass radiation to anyone else, so there is no need to avoid close contact with other people.
  • You can be sexually active during your treatment unless your doctor gives you other instructions.
  • If you are fertile, you must use birth control during treatment. We do not know what short- or long-term effects the treatment will have on sperm. Sperm could be changed and cause birth defects. It is generally recommended that you not conceive a child for 2 years after treatment is completed. If you want to conceive a child in the future, you will need to arrange for sperm banking. If you have banked sperm, you can use it when you are ready to have a child. Please discuss this thoroughly with your doctor before you begin your treatment.
  • You may have concerns about the effects of cancer on your sexuality. The American Cancer Society publishes an excellent resource called Sexuality for the Man With Cancer. Call 1-800-227-2345 to get a copy or go to:
  • MSK has a Male Sexual and Reproductive Medicine Program to help men address the impact of their disease and treatment on sexual health. You can meet with a specialist before, during, or after your treatment. Call 646-888-6024 to make an appointment.
  • Some men have a burning sensation during ejaculation. In most men, it goes away 1 to 2 months after treatment is done.
  • Some men develop sexual changes after treatment is done. You may have:
    • Erectile dysfunction (difficultly or inability to have or maintain an erection)
    • A change in the sensation of orgasm
    • A change in the amount or consistency of your ejaculation

These sexual changes may occur many months or even years after treatment. There are treatments for erectile dysfunction. We can give you a referral to a doctor who treats these problems, if you wish.

Skin reactions

During treatment, you will probably not notice any changes in your skin in the area being treated. However, you may lose some or all of the hair in your pubic area. The hair will usually grow back 2 to 4 months after treatment is done; however, the color and texture may be different. Below are guidelines to care for your skin in the area being treated.

  • Bathe or shower daily with warm water and a mild soap.
  • Do not use any moisturizers, lotions, or creams in the treated area unless your doctor or nurse tells you to.

Emotional health

The diagnosis and treatment of cancer can be a very stressful and overwhelming event. You may feel depressed, anxious, confused, afraid, or angry. You may have strong feelings about any permanent changes. These changes can have an impact on your emotional well-being. Help is available for you at any time. If you would like counseling, your nurse can give you a referral to see a social worker, psychiatrist, or counselor.

Also, you may find it comforting to speak with a cancer survivor or caregiver who has been through a similar treatment. Through our Patient-to-Patient Support Program, you have the chance to speak with former patients and caregivers. To learn more about this program, call 212-639-5980.

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After You Complete Treatment

At the end of treatment, you will be told how often to see your doctors for follow-up visits. Keeping your follow-up appointments will help us identify any late effects of treatment.

Radiation can cause permanent side effects in the bladder and bowel. Many people are not aware of these changes and do not have any symptoms. However, some people will develop symptoms 4 months or more after treatment. These may be similar to the ones you had during treatment. However, there is a very small chance that you may develop others. These are very rare. They include:

  • Narrowing of the opening out of the bladder
  • Loss of urinary control
  • Blood in the urine
  • Rectal bleeding

These symptoms may come and go over time. They can also be persistent and chronic. Even if you do not develop any late side effects, remember that the tissues in your bladder and rectum have been affected by the treatment. Call your radiation oncologist if you:

  • Have any new urinary or bladder symptoms
  • Need to have a colonoscopy
  • Need any type of rectal procedure

Write down any questions and concerns you have before your visits. Bring this and a list of all your medications. If you are running low on any medication, let your doctor know before you run out. You can also call your doctor or nurse any time between follow-up visits if you have any questions or develop any problems.

You may have questions about diet or supplements after treatment. You can start taking other vitamins 1 month after your treatment is done. If you would like to speak with a dietitian about your diet or supplements, please ask your nurse to arrange this.

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If you have any questions or concerns, talk with a member of your healthcare team. You can reach them Monday through Friday from 9:00 am to 5:00 pm at ____________________. After 5:00 pm, during the weekend, and on holidays, please call____________________. If there’s no number listed, or you’re not sure, call 212-639-2000.
Intensity-Modulated Radiation Therapy to the Prostate
©2015 Memorial Sloan Kettering Cancer Center - Generated on November 25, 2015