What is simulation?
Before actual radiation therapy begins, a radiation therapist, under the supervision of a radiation oncologist, plans the details of the patient’s therapy. This step is called simulation. It is important that patients are treated in exactly the same way each time so the correct amount of radiation is delivered to a precise area. Simulation is the treatment-planning step that customizes each individual’s treatment.
The simulation procedure is performed in a room with special fluoroscopic X-ray equipment (that produces an X-ray movie) or CT scanner. These simulate the action of actual treatment machine, but without radiation. The therapist will use molds, masks, or blocks to make sure your alignment is correct and to help you lie still. Harmless laser light beams also help us accurately position our patients.
Measuring body contours allows us to use computerized treatment planning. Radiation beams are often directed from several different directions to optimize treatment.
Once all measurements are taken, we usually mark the skin to identify the precise area to be treated. Sometimes we use tiny permanent tattoos (small dots the size of a freckle). A contrast medium, taken by mouth or given intravenously, is sometimes needed to improve the contrast of a scan. Your radiation oncologist will discuss this or any other necessary procedures with you at the time of simulation.
The simulation procedure typically takes 30 minutes to about an hour. During this time, you will need to lie flat and still on a somewhat hard table.
The information we collect from the simulation is sent to radiation dosimetrists and physicists, who, under the supervision of the radiation oncologist, calculate appropriate settings for each individual patient.