Simulation is the first step in planning a course of radiation treatment. Simulation helps define the treatment area or the exact spot in the body where the treatment will be aimed. During simulation the Radiation Therapist will use a special X-ray machine, called a simulator or CT scanner, to set up the treatment area(s) according to the doctor's direction.
Once a treatment area (portal) is determined, the skin over the area is marked with colored ink. This allows the Radiation Therapist to position the patient so the treatment is administered to the same place each time. Since it is important to be in the same position each time a treatment is administered, sometimes body molds, head masks or other devices may be used.
Simulation is important because many cancers are located deep within the body. The Radiation Oncologist must know the exact location of the cancer in relation to a patient’s body surface and surrounding normal tissues. This allows treatment to be focused on cancerous cells while sparing normal cells.