|Dr. Joshua Petit and staff work with a
patient on the new TrueBeam STx
To be most effective, radiation therapy must be aimed precisely at the same target or targets each and every time treatment is given. Simulation is the starting point in planning your radiation therapy treatments. This process exactly measures your body and marks your skin to help your team direct the beams of radiation safely and exactly to their intended targets.
During simulation, your radiation oncologist and radiation therapist place you on the simulation machine in the exact position you will be in during the actual treatment. Detailed imaging scans show the tumor and the normal areas around it and are used to exactly map the radiation target.
Your radiation therapist, under your doctor's supervision, then marks the area to be treated directly on your skin or on immobilization devices. Immobilization devices are molds, casts, headrests or other devices that help you remain in the same position during the entire treatment. The radiation therapist marks your skin and/or the immobilization devices either with a bright, temporary paint or a set of small, permanent tattoos.
Your radiation oncologist may request that special blocks or shields be made for you. These blocks or shields are put in the external beam therapy machine before each of your treatments and are used to shape the radiation to your tumor and keep the rays from hitting normal tissue.
Once you have finished with the simulation, your radiation oncologist and other members of the treatment team review the information from simulation along with your previous medical tests to develop a treatment plan. Often, a special treatment planning CT scan is done to help with the simulation and treatment planning. This CT scan is in addition to your diagnostic CT scan. Frequently, sophisticated treatment-planning computer software is used to help design the best possible treatment plan. After reviewing all of this information, your doctor will write a prescription that outlines exactly how much radiation you will receive and to what parts of your body.
Treatments are usually scheduled five days a week, Monday through Friday, and continue for from one to 10 weeks (length of schedule varies by treatments). The number of radiation treatments you will need depends on the size, location and type of cancer you have, the goals of treatment, your general health and other medical treatments you may be receiving.
To Learn More
The American Society for Radiation Oncology provides excellent patient education and a video for learning about radiation therapy treatments.