Your CT simulation appointment
To be safe and effective, the beams used in radiation therapy must be aimed precisely at the same target each and every time you receive radiation. Anyone receiving external beam radiation is scheduled for a simulation appointment. The purpose of this appointment is to identify the exact positioning of your body for all future treatments.
Although this appointment simulates a radiation treatment, it is only to determine the best body position for your treatment and to take images that will be used to create a detailed map for future treatments. The mapping of your body during the simulation allows the treatment team to plan your therapy so that the radiation focuses on the tumor and avoids the healthy tissues that surround it.
During this appointment the radiation therapist places you on a simulation machine table. To ensure that your body doesn’t accidentally move during this imaging session or future treatments, the radiation therapist uses immobilization devices such as molds, casts and beanbag-like rests designed to keep you still. You will be asked to lie very still while X-rays or scans are taken to define the treatment area.
Casting. Depending on the part of your body being treated, we may need to create a meshlike plastic cast of your body. The casting process yields an exact mold of the body position you need to maintain during radiation treatments. In all subsequent visits, the radiation therapist will carefully place the cast over your body and secure it to the table.
Tattoos. During the simulation appointment, the radiation therapist also puts small marks (tattoos or dots of colored ink) on your skin to indicate the treatment area. Tattoos are about the size of a freckle and will remain on your skin for the rest of your life. Ink dots will fade over time. The radiation therapist uses these marks each day to ensure that you are positioned correctly.
Once we’ve established the position that will be used for all future treatments, we document the correct position through photographs that are stored in your electronic health record. One or more members of the radiation team will be in the room during the simulation.