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Pelvic radiation: What to expect

When it comes to treatment day, you might be anxious or not sure what to expect. We’re here to help!

Before the procedure

If radiation is a part of your treatment plan, you will probably start off with a visit to your radiation oncologist. They will explain the details of what you’ll be receiving, and what to expect. During this appointment, you should have an opportunity to ask any questions that you have about the treatment.


After your meeting with the radiation oncologist, you will probably schedule an appointment for your simulation. The purpose of the simulation is to map out an accurate and effective radiation plan so everything goes smoothly day of treatment.

When you arrive at your simulation, the technicians will start by performing a scan. This helps the radiation oncologist decide where to aim the radiation beams and how much radiation to deliver to each area. 

First, they will ask you to lie down on the machine, and help you find a good and comfortable position. For pelvic radiation, you will probably lie on your back, with your legs in a “frog position,” or on your stomach.

The technicians may use molds or other devices to help keep your body still, or help keep specific body parts outside the field of radiation. These will be the same molds you use during the real thing.

In some places, you might be offered to have a vaginal dilator in place during each session. This is done to help move the vaginal wall away from the field of radiation. If you’re comfortable with this, you can ask for this adjustment. The simulation will also need to be done with the dilator in place.

After you’re positioned correctly, you will receive a few small tattoos on your abdomen. Yes, real tattoos! These small dots help the technician position you correctly in future sessions. 

After getting the tattoos, you will lie still on the machine while pictures are taken. This helps your radiation oncologist plan your treatment. At the end of your simulation, you should be given a schedule for your radiation treatments.

Treatment day

Your appointment will be fairly similar to the simulation. Many patients are asked to come to treatment with a full bladder. This helps protect your small intestines from receiving radiation damage. If that’s the case for you, make sure to drink plenty of fluids before your treatment — but not so many that you’re uncomfortable!

If you want to have a vaginal dilator for your treatment, this will also be placed.

You will lie down on the machine. You’ll need to be completely still for a while, so make sure to let the technician know if you are uncomfortable. The treatment should only take about 10 to 15 minutes.

During this time, the machine will rotate several times around your body, delivering the radiation treatment. You will not be able to see or feel the beams entering your body. It won’t hurt at all!

The technicians operating the machine will be in another room, but they should be able to see and hear you clearly. So don’t be afraid to speak up if you have any concerns during treatment.

After treatment has finished, you can go home and get ready to come back the next day.

After the procedure

If you’re having long course radiation, you will receive treatment for 5 to 6 weeks. If you’re having short course radiation, you’ll only be treated for 5 days.

You will probably meet with your radiation oncologist at least once during your treatment, just to check on how things are going. Be sure to ask any questions you have about treatment, and report any side effects you’re experiencing. Side effects usually start anywhere from a couple days to severeal weeks into treatment — and they will probably continue for a few weeks after treatment has finished.

When you are done with your radiation course, you will be given a follow up appointment to check in with your radiologist a few weeks later.

Want to learn more about what to expect on treatment day? 

Check out this article by Memorial Sloan Kettering.

Diagnosed: July 2019

Stage: II

Type: Rectal cancer

After receiving the news at my colonoscopy that I was cancer-arse (rectal cancer), my first meeting was with the surgeon. He told me I would need chemotherapy and radiation, followed by two surgeries. After hearing that, I went home, immediately hopped on Amazon, and ordered a head wrap in preparation for chemotherapy.

Once I met with my Oncologist, who had ordered and reviewed additional tests to resolve a staging discrepancy between T3 and T2, he decided that the type of chemotherapy he would prescribe for me is one that does not cause hair loss. I am now in search of a dress to match my head wrap, so it can have a useful purpose in my wardrobe. I learned from that to ask questions, including ones to which I think I already know the answer, and to stay in the moment as treatment evolved, resisting the urge to get ahead of things. 

The chemo medication I was prescribed was a pill form, Capecitabine (Xeloda). It arrived by mail in a rather terrifying looking bag with special handling instructions:

Upon removal, they were much more innocent looking pretty pink pills of precious poison. For my treatment plan, I took 1800mg twice daily, 12 hours apart concurrent with radiation for 42 days. Choosing a routine that works for one’s individual schedule is important, so doses are not missed. I worked long days, so I took my first dose right away in the morning at 6am and then went to radiation immediately afterwards, taking the second dose at 6pm right before my second job. 

The only challenge to this was that I was unable to have food until after radiation. It was probably due to this food delay that I experienced some nausea with the morning dose of chemotherapy. It was not severe, so I managed it by distraction, breathing exercises, and eating a cracker right after radiation. The other side effects I experienced were diarrhea and fatigue. The diarrhea improved over the course of treatment and may have been partially or even mostly caused by the cancer itself.  Fatigue was the most challenging side-effect for me. Both the chemo drug and radiation caused fatigue. I was unable to take time off work and just kept putting one foot in front of the other each day, resting when I could. Radiation fatigue has weakness in addition to tiredness, which I definitely experienced (I recall the moment I realized that manufacturers were not, in fact, putting lids on more tightly than they used to). If you do experience side effects to chemotherapy, there are medications to treat some side effects that you could discuss with your prescriber. Otherwise, know that side effects from chemotherapy resolve after treatment has ended and you will feel better.

Want to learn more about radiation?

Join one of our COLONTOWN Facebook groups:

  • In Rectalburgh, we discuss all things related to rectal cancer — including long and short course radiation treatment.
  • Corner Cupboard is the place to discuss treatment side effects and management.

Want to join? Fill out the registration form here.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: April 28, 2022