Preparing for prostate radiation therapy involves several steps that begin weeks before your first treatment session and continue as a daily routine throughout the course of treatment. Some preparation is medical, handled by your care team, while other parts are entirely in your hands: what you eat, how much water you drink, and how you condition your body for recovery. Here’s what to expect at each stage.
Pre-Treatment Procedures Your Team Will Schedule
Before radiation can begin, your care team needs to ensure the radiation beam hits the prostate with precision every single day. Two common procedures make this possible: fiducial marker placement and, in some cases, a rectal spacer injection.
Fiducial markers are tiny gold seeds (usually three) implanted directly into the prostate. They show up clearly on imaging scans and act as reference points so the radiation machine can lock onto the exact position of your prostate before each session. The placement is typically done under local anesthesia through a needle guided by ultrasound, similar to a prostate biopsy. You may experience mild soreness or brief bleeding afterward. If you take blood thinners or medications containing aspirin or ibuprofen, you’ll need to stop them 2 to 7 days before the procedure, depending on the specific medication. Talk to the doctor who prescribed those medications to set up a safe plan for pausing and restarting them.
A rectal spacer, often a hydrogel material, is another option your radiation oncologist may recommend. It’s injected between the prostate and the rectum under ultrasound guidance, creating a physical cushion of space that pushes the rectum farther from the radiation field. This reduces the dose of radiation the rectal wall absorbs, which translates directly into fewer bowel side effects during and after treatment. The spacer gradually dissolves on its own over several months. Not every patient needs one, so your team will discuss whether it makes sense for your specific treatment plan.
The Simulation Session
A few weeks before treatment starts, you’ll have a simulation appointment. This is not a treatment session. It’s a detailed planning session where your team maps out exactly how radiation will be delivered.
You’ll lie on a treatment table while a custom immobilization mold is made around your lower body. This mold holds you in the same position for every future session, which is critical for accuracy. Once it hardens, the team places small tattoo dots (about the size of a freckle) on your skin to mark reference points. These permanent marks help the therapists align you precisely each day.
Next comes imaging. You’ll have a CT scan, and often an MRI as well, while lying in the mold. The MRI portion takes roughly 25 minutes. These scans give your radiation oncologist a detailed 3D picture of your prostate, the surrounding organs, and the fiducial markers. After the simulation, your team spends anywhere from a few days to a few weeks designing a personalized treatment plan, calculating the exact angles and doses of radiation. You won’t need to do anything during this waiting period.
Hormone Therapy Before Radiation
If you have high-risk prostate cancer, your oncologist will likely start you on hormone therapy (androgen deprivation therapy) before radiation begins. This treatment lowers testosterone levels to shrink the tumor, making the radiation more effective. Multiple clinical trials have shown that combining hormone therapy with radiation improves survival compared to radiation alone.
The timing matters. Research from the National Cancer Database found that starting hormone therapy 8 to 11 weeks before the first radiation session was associated with the best overall survival outcomes, compared to starting it closer to the radiation start date. Your oncologist will determine whether hormone therapy applies to your situation and when to begin it. Common side effects include hot flashes, fatigue, and reduced libido, so knowing these are coming can help you plan accordingly.
What to Eat (and Avoid)
Diet plays a surprisingly important role in prostate radiation therapy. The goal is to minimize gas and keep your bowel as consistent as possible from day to day. When the rectum is distended with gas, it shifts position slightly, which can push it closer to the radiation field and increase side effects. A consistent, predictable bowel also means the prostate stays in a more stable position for accurate targeting.
The most studied dietary approach is reducing foods high in fermentable carbohydrates, sometimes called FODMAPs. These are short-chain carbohydrates that are poorly absorbed and highly fermentable, meaning they produce a lot of gas in the colon. Your radiation team may give you a specific food list broken down by category: dairy products, grains, fruits, vegetables, nuts, legumes, honey and syrups, sweeteners, and beverages. Each category will include items to avoid and lower-gas alternatives you can swap in.
In general, reducing lactose, cutting back on insoluble fiber, and avoiding known gas-producing foods like beans, onions, garlic, and certain fruits will help. Some programs also recommend a mild fiber supplement like psyllium to keep bowel movements regular without creating excess gas. Start following the dietary guidelines at least a few days before your simulation scan, since the same bowel conditions you want during treatment should also be present during planning.
Daily Bladder Preparation
For each treatment session, you’ll need to arrive with a comfortably full bladder. A full bladder pushes the small intestine up and away from the radiation field, reducing the dose those tissues receive. It also helps keep the prostate in a consistent position day to day.
The specific instructions vary by clinic, but a common protocol works like this: empty your bladder completely, then drink a set amount of water (typically 300 to 500 ml, roughly 10 to 17 ounces) and wait 30 to 60 minutes before your session. The key is consistency. Drinking the same amount and waiting the same length of time each day produces a similar bladder volume, which keeps your internal anatomy in the same configuration the treatment plan was designed around. If your bladder is too full or too empty when you arrive, the therapists may ask you to wait or try again, so building this routine into your daily schedule early helps avoid delays.
Strengthening Your Pelvic Floor
Radiation to the prostate can weaken the muscles that control urine flow, sometimes leading to leakage or urgency during or after treatment. Pelvic floor exercises, commonly called Kegels, can help you maintain better urinary control if you start them before treatment begins.
To find the right muscles, try stopping your urine stream midflow. The muscles you squeeze to do that are your pelvic floor muscles. Once you’ve identified them, practice contracting and holding for a few seconds, then releasing. Repeat this 10 to 15 times, several times a day. The goal is to build strength and awareness in these muscles so they’re better prepared to handle the stress radiation places on the area. Starting a few weeks before your first session gives you a meaningful head start.
What Treatment Days Look Like
The length and frequency of your radiation schedule depends on the type of treatment your oncologist recommends. A newer approach called stereotactic body radiation therapy (SBRT) delivers high doses in just five sessions over one to two weeks. Each session takes about 20 to 30 minutes, and the experience feels similar to getting an X-ray: you lie still on the table while the machine moves around you. You won’t feel the radiation itself.
Conventional radiation therapy uses smaller daily doses spread over a longer period, typically five days a week for several weeks. Each daily session is shorter, often 10 to 15 minutes of actual beam time, though setup and imaging verification add to the total appointment length. Whichever approach you’re receiving, the daily routine of bladder filling, dietary management, and arriving on schedule stays the same throughout.
Plan for the time commitment by arranging transportation, adjusting work schedules, and keeping your mornings or appointment times as free from competing obligations as possible. Fatigue tends to build gradually over the course of treatment, so front-loading any physically demanding tasks or errands in the early weeks is a practical strategy.