CT simulation is a process used by the radiation therapy team to determine the exact location, shape, and size of the tumor to be treated. This is done in a separate room that contains a treatment table and special imaging equipment.
During simulation, you will lie on the treatment table. The radiation therapist will position you in the precise way you will ultimately be treated and then watch you through a window while a CT scanner takes images of the treatment site. You must lie still during simulation so the exact area to be treated can be pinpointed.
The radiation therapist may use special pads, body molds or other devices to help hold your body comfortably in the proper position.
After your radiation oncologist locates the exact area to be treated, your skin may be marked with several small tattoos, each the size of a freckle. These tiny, permanent dots will be used to make sure you are accurately positioned at each treatment session.
A CT simulation for radiation therapy follows your initial consultation in our Radiation Therapy Department. CT simulation includes a CT scan of the area of your body to be treated with radiation. The CT images acquired during your scan will be reconstructed and used to design the best and most precise treatment plan for you. The simulation portion of your radiation therapy regiment ensures that your treatments will target the area of concern, while missing surrounding critical structures.
What to expect?
You will begin the simulation by having a CT scan of the area of your body to be treated with radiation therapy. We will ensure that you are as comfortable as possible for your scan, as the goal is to position you the same way every day during your treatment regimen. The very center of the treatment area will be defined and marked as a reference point to be used during your treatment. We may need to use permanent ink to create a very small tattoo in this area. This will be discussed with you before simulation and only takes a couple of seconds.
The second half of simulation involves the creation of an immobilization device that will be utilized over the duration of your treatment to keep you in the same position each and every time you are treated. A mask may be used for treatments near the head, and a “cradle” or “mold” may be cast around the area of interest if it is located on the torso or body . Marks will be made on the mask or mold to serve as reference points that help our radiation therapists place you in the correct and exact position every day, ensuring your treatments are as accurate and precise as possible.
How to prepare?
Your radiation oncologist will give you specific instructions on how to prepare for your CT simulation during your initial consult. Simulation can sometimes be scheduled the next day, depending on availability.
What happens after simulation?
The images obtained during your CT simulation will be used to plan your treatments. Depending on the type of treatment you will receive and the various tasks associated with it, you will begin radiation therapy 1-10 days after initial simulation.