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Simulation for Radiation Therapy

October 29, 2021

What is a “simulation” or “treatment planning session” for radiation treatment?

If your doctor has recommended radiation therapy, they will likely schedule an appointment for a simulation, or a treatment planning session. Simulation is the process of positioning your body in a way that is comfortable and that can be reproduced for each radiation treatment. Radiation therapy precisely and accurately targets tumors, so a simulation is necessary for delivering customized radiation treatment for each patient.

How do I prepare for simulation?

Your doctor may have you prepare for simulation in a special way, depending on the area of your body being treated. This may involve drinking water to fill your bladder, or having an IV started for contrast during your scan. Your nurse will review any preparation instructions with you prior to this appointment.

You can likely eat and drink as normally the day of your simulation, if no preparation is required. Some patients will be asked to change into an exam gown. Consider wearing clothes that are easy to change in and out of.

Please arrive on time.

How long will the simulation take?

Typically, a simulation appointment will take between 30 minutes to 1 hour. Since each patient is unique, each simulation is customized and may vary. If you have pain while lying in one position for a long period of time, you may want to discuss managing your pain with your nurse or doctor before simulation.

What happens during simulation?

At the time of simulation, you will confirm your name, date of birth, and site of treatment for safety reasons. You will then be directed into a room with a CT scanner by a radiation therapist. Radiation therapists are specially trained to prepare and treat patients with radiation. Your therapist will help position your body in a way that is reproducible for each treatment and allows your doctor to target the tumor while avoiding normal structures. Sometimes, we will make a mold or a mask that helps you stay in the correct position during treatment. Then, the therapist will place marks on your skin using a marker or small tattoo, which helps us to align you in the correct position for treatment. These marks must stay on your body until treatments start, so we typically cover them with a waterproof sticker.

Once your marks are drawn, the therapists will walk out of the room to obtain a CT scan of the part of your body where your doctor will give radiation. They will be able to see and hear you at all times, and they will let you know what is happening. This CT scan is used to customize your treatment.

If you are pregnant, or think you could be pregnant, please tell your doctor, nurse, or our staff prior to your simulation. You should not have a CT scan if there is a chance you are pregnant.

What happens next?

When you leave the simulation, you will be scheduled for your next appointment.

After simulation, your CT scan is sent to your doctor and the planning team to customize your radiation treatment. Radiation planning and customization is a detailed process, which often takes 1-2 weeks to complete. When your doctor approves the plan for your radiation treatment, there are special checks done to ensure the machines are giving the radiation as planned by the computer. This is for your safety.

For more information, please view my “What to Expect: Radiation Therapy Simulation Appointment” video.