Open Accessibility Menu

Simulation (Treatment Planning)

Simulation is a process carried out by the radiation therapist under the supervision of the radiation oncologist. It is a mock-up procedure of a patient treatment. Inside the simulation room is a CT scanner specifically designed for the radiation therapy department. Simulation is the beginning step of starting your radiation therapy treatment.

How Is Simulation Performed?

The main goal of simulation is to assure that you will be in the same exact position every day for your radiation therapy treatments. To help achieve this, various immobilization devices can be used and/or made. These devices differ depending on the area of the body in which you are being treated.

The first step in the CT simulation is to make sure you are straight; there are lasers is the room that help the radiation therapist straighten you. To assure that you are straight, the radiation therapist does a quick image on the CT scanner called a scout that shows how straight you are. The radiation therapist may come in to move you a bit if you are not completely straight, but your main goal is just to hold still.

After you are in a reproducible position and straightened, a CT scan of the area to be treated will be done. Once the scan is complete the radiation oncologist will come into the CT room and look at the scan. At this point the radiation oncologist will mark the exact area on the CT scan that he or she wants to treat. Once this is done the lasers in the room will move to that point, and the radiation therapist will make marks on your skin with a Sharpie® marker. After all the marks are made you will get a few permanent tiny tattoos. These tattoos are given to ensure that there is a permanent record of your treatment, and to enable you to be positioned in exactly the same way each day for treatment.

Different Types of Immobilization That May Be Used

Wingboard – A wingboard may be used to position both arms above your head. This is commonly used with patients with lung and esophageal cancer. Having your arms above your head allows for a better treatment plan to be designed.

Vac Lok™ – A Vac Lok™ is like a bean bag and consists of a cushion and vacuum compression pump. The patient is placed in the treatment position on a partially inflated cushion. The Vac Lok bag is molded around the area to be immobilized and then deflated so that it becomes rigid. Vac Lok bags are typically used to keep extremities (legs as well as arms) immobilized so that you are in the same position every day.

Aquaplast (thermoplastic) Mask – These masks become pliable when placed in a warm oven. When pliable the mask can be molded around the patient’s head and neck area. The masks are perforated and allow for normal breathing. When your treatment requires a mask, the treatment marks are made right on the mask so there is no need for marks to be made on your face.

Breast Board – A breast board is used to position the arms and shoulders away from the chest and at the same time elevate the patient on an adjustable-angle board for positioning and daily reproducibility. A wingboard is typically attached to the breast board. We have two types of breast boards in our department: with one breast board, patients lie on their back face up; with the other breast board, the patients lie on their stomach face down. Your physician will work with you to determine what breast board is right for you.

Procedures That May Be Done as Part of Your Simulation

These procedures are typically done only during the time of simulation and are not repeated during the course of your radiation therapy treatment.

Contrast Agents – When performing a CT scan, contrast media may be used to help differentiate anatomic structures or highlight an abnormality. Contrast can be administered via three methods: intravenously (IV), orally or rectally. The most common methods of administering contrast during CT simulation are orally and intravenously.

Rectal Catheterization – A rectal catheter is a hollow, flexible, soft rubber tube which is inserted into the rectum. A special contrast medium is injected into the rectum through this catheter. The contrast medium outlines the rectum and makes it easier to visualize on the CT scan.

After Simulation Is Complete

Once your simulation is complete, the radiation therapist will either give you an appointment card with your starting date of treatment or let you know that we will be calling you within a week or two to schedule your first appointment. Treatment planning varies depending on the type of treatment you are having, so it may take anywhere from three days to a couple of weeks to plan your treatment.

Latest News