Prostate radiation treatment is an outpatient procedure that feels similar to getting an X-ray. You won’t feel the radiation itself, but the preparation, daily routine, and side effects that build over the weeks of treatment are worth understanding before you start. Here’s what the process looks like from start to finish.
Types of Prostate Radiation
There are three main approaches, and which one your team recommends will shape the length and rhythm of your treatment.
External beam radiation (EBRT) is the most common. A machine directs focused beams at the prostate from outside the body. The standard version, called intensity-modulated radiation therapy (IMRT), typically runs five days a week for four to seven and a half weeks. A newer, shorter-course option called stereotactic body radiation therapy (SBRT) delivers higher doses per session and finishes in just five visits spread over one to two weeks. A large trial published through Harvard Health found SBRT to be as effective as the longer schedules.
Brachytherapy places radioactive material directly inside the prostate. In the permanent (low-dose-rate) version, tiny radioactive seeds are implanted and left in place. In the temporary (high-dose-rate) version, a stronger source is inserted for just 5 to 20 minutes per session, typically over one or two treatments across a few days. Some treatment plans combine brachytherapy with a shorter course of external beam radiation.
The Planning Phase Before Treatment Starts
Before any radiation is delivered, you’ll go through a planning session called a simulation. This appointment takes longer than a regular treatment visit because the team needs to map the exact size, shape, and position of your prostate so the radiation can be aimed precisely.
You’ll lie on a table while a CT scan (and sometimes an MRI) captures detailed images. The team will create a custom mold or use body positioning devices so you can be placed in the identical position every day. Small tattoo dots, about the size of a freckle, are often marked on your skin to help with daily alignment.
Many centers also place fiducial markers before simulation. These are tiny gold seeds, usually three, implanted into the prostate in a triangular arrangement under ultrasound guidance. They show up clearly on imaging and help the team verify the prostate’s exact position at every session, which matters because the gland can shift slightly day to day based on bladder and bowel fullness. The implantation procedure is done under local anesthesia, either through the rectum or through the skin between the scrotum and rectum. It’s generally well tolerated, though brief discomfort, minor bleeding, or soreness can occur.
Your doctor may also recommend a hydrogel spacer (often called SpaceOAR). This is a gel injected between the prostate and the rectum that pushes the rectal wall farther from the radiation field, reducing the dose your rectum receives. The injection solidifies in about 10 seconds and holds its shape for roughly three months before the body gradually absorbs it over the following three months. It’s placed in a single procedure before treatment begins.
What a Daily Session Feels Like
Each external beam session lasts less than an hour, but the actual radiation delivery takes only a few minutes. Most of the appointment is setup: changing into a gown, getting positioned on the table, and running imaging checks to confirm alignment. For SBRT, sessions run about 20 to 30 minutes total because the higher-precision targeting requires more detailed verification imaging.
You lie still on a flat table while the machine rotates around you. There’s no pain, no heat, and no sensation from the beam. You can breathe normally. The room will be quiet except for the hum of the machine, and therapists will watch you on a camera from the next room.
Before each session, you’ll need to follow two preparation steps. First, try to have a bowel movement within an hour of your appointment. An empty rectum keeps the prostate in a more consistent position and reduces the amount of bowel tissue in the radiation path. If you’re having trouble with regularity, your care team can adjust your prep routine. Second, you’ll need a comfortably full bladder. A full bladder pushes small intestine up and away from the treatment area while also helping stabilize the prostate’s position. Your team will give you specific instructions on how much water to drink and when to drink it before each visit.
When Side Effects Typically Appear
The first week or two of treatment usually feels uneventful. Side effects most often begin around the second or third week as the cumulative radiation dose builds. They tend to peak near the end of treatment and can linger for several weeks afterward. Most resolve within one to two months of finishing.
Urinary changes are among the most common. You may notice a more frequent or urgent need to urinate, a weaker stream, or mild burning during urination. These symptoms typically start three to five weeks into treatment and clear up within two to eight weeks after the final session. Drinking plenty of water (aim for about 64 ounces a day) helps keep the urinary tract flushed.
Bowel changes can include looser stools, more frequent bowel movements, or a feeling of urgency. These tend to follow a similar timeline, building in the later weeks of treatment and fading afterward.
Fatigue is gradual. You may feel more tired than usual as treatment progresses, though most people can maintain their normal routines with some adjustments. The tiredness typically lifts in the weeks after treatment wraps up.
Eating to Reduce Gut Symptoms
Small dietary adjustments during treatment can make a meaningful difference in how your bowels handle the radiation. The goal is to keep digestion moving smoothly without producing excess gas or irritation.
- Eat regularly. Skipping meals can slow your digestive system and worsen symptoms.
- Limit fatty and fried foods. Fat slows digestion, giving food more time to ferment and produce gas. Cut back on red meat, pork, and deep-fried items.
- Reduce sugar and artificial sweeteners. Sorbitol, mannitol, and xylitol in particular can increase gas and loose stools.
- Skip carbonated drinks. They introduce extra gas into your digestive tract.
- Go easy on fiber if you’re not used to it. Add one or two fibrous foods per day at most, and avoid products with inulin or chicory root fiber additives.
- Try lactose-free dairy if milk products cause bloating or stomach upset.
Staying Active During Treatment
Current guidelines encourage staying as physically active as you can during radiation. Exercise can help manage fatigue, maintain muscle strength, and support your mood through the weeks of daily appointments. Walking, light resistance training, and gentle stretching are all reasonable options for most people. If you have bone metastases, you should minimize load on affected areas. One activity to avoid: swimming pools are generally discouraged during radiation because chlorine and bacteria can irritate the skin in the treated area.
Tracking Your PSA After Treatment
Once radiation is complete, your PSA level becomes the primary way your medical team monitors how well the treatment worked. Unlike surgery, where PSA drops to near zero within weeks, radiation produces a slow, gradual decline. Your PSA will be checked periodically, typically every few months in the first year or two.
The lowest point your PSA reaches is called the nadir. For men who receive radiation combined with hormone therapy, the median time to reach the nadir is about five months, and roughly 83% achieve a PSA of 0.1 or below by six months. Reaching that milestone within the first year is associated with better long-term outcomes.
A PSA “bounce,” a small temporary rise followed by another decline, is fairly common after radiation and doesn’t necessarily mean the cancer is returning. The standard definition of a true relapse after radiation is a PSA rise of 2.0 or more above your lowest post-treatment value. Your team will look at the overall trend over multiple readings rather than reacting to a single number.