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Radiation therapy is the use of high energy X-rays to kill cancer cells.
Radiation therapy is used to target tumors in specific locations. By delivering radiation to the tumor’s exact location, doctors hope to shrink its size. Sometimes, radiation takes place before surgery or chemotherapy is given to make the tumor small enough to remove, and other times, radiation takes place without the need for surgery.
Radiation therapy works by destroying or damaging rapidly growing cells, such as cancer cells. It damages cells only in the area of the body where the radiation is given. Unlike chemotherapy, radiation does not cause cell damage throughout the body. It can, however, damage healthy cells in the area being irradiated, but normal cells are better able to repair themselves.
During external beam radiation therapy, radiation beams come out of a machine called a linear accelerator. The beams are aimed at the tumor (either where it is or where it was before surgery and/or chemotherapy). You don’t see it, feel it, or taste it; it is completely invisible.
If your child needs to receive radiation, the radiation field (area) will be measured precisely and marked on your child’s body. This process is called “simulation.” Do not wash off the markings until after the radiation treatments are finished.
Simulation: To be most effective, radiation therapy must be aimed precisely at the same spot every time treatment is given. Simulation is the process of measuring your child’s body and marking the skin to help direct the beams of radiation safely and exactly to the intended locations.
Your radiation oncologist and radiation therapist will place your child on the simulation machine in the exact position that will be used during the actual treatment. Depending on what area of the body is going to be treated, simulation may include an immobilization device to ensure that your child remains in the same position every day during the entire treatment.
Treatment Planning: Once the simulation is finished, the radiation oncologist and other members of the treatment team review the information obtained during simulation along with previous medical tests to develop a treatment plan. The doctor will write a prescription that outlines exactly how much radiation is to be given and where. The complexity of the treatment plan dictates how soon after simulation that treatment will begin. Not all cancers are treated with the same amount of radiation; the duration of treatment is based on the tumor type and sometimes, the age of the child.
First Day: Before the first dose of radiation is given, the Radiation Oncology Unit will take treatment verification films (also called beam films or port films). These verify that the area being treated is in fact the exact area the doctor planned. These films need to be approved by the doctor before the first dose of radiation is given.
Daily Treatments: Every day, the radiation therapists will assure correct position, including use of the immobilization device if that is a part of treatment. Once correct placement is assured, the therapists will leave the room and go to the control area to closely monitor your child on a television screen. There is a microphone in the treatment room so your child can always talk with the therapists. The machine can be stopped at any time if your child is feeling sick or uncomfortable. Each session is painless; you don’t see it, taste it, or smell it. It is just like getting an X-ray. The machine might make noises during treatment that sound like clicking, knocking or whirring; this is normal.
Your child will be on the treatment table for 10-30 minutes; most of this time is spent setting up. Treatments are usually scheduled five days a week, Monday through Friday, and continue for one to 10 weeks depending on the type of cancer being treated.
Weekly Status Checks: Your radiation oncologist and nurse will see your child regularly during treatment to follow progress. Be sure to share any questions or concerns that you or your child may have during these visits or any time during treatment. They will evaluate whether your child is having any side effects and recommend treatments for those side effects (such as medication). As treatment progresses, your doctor may make changes in the schedule or treatment plan depending on response or reaction to the therapy.
Your radiation therapy team may also meet on a regular basis with other healthcare professionals to review your child’s case. This will ensure that treatment is proceeding as planned. During these sessions, all members of the team discuss progress as well as any concerns.
Weekly Port/Beam Films: To make sure the radiation beams are going exactly where they are designed to go throughout the course of treatment, once a week, the therapists will take port or beam films for the radiation oncologist to approve. These are the same type of films that were taken on the first day. Your radiation oncologist must approve these films in order to continue radiation. Your child may be on the table for a few more minutes than usual on the day of port/beam films. These films do not show the tumor’s response to radiation.
The most common side effect, regardless of the area treated, is fatigue. The fatigue your child may experience is usually not very severe, and children can often continue all or some of their normal daily activities. Another side effect is decreased blood counts. If a large enough area is treated, the production of blood cells can be decreased. The radiation oncologist will monitor your child’s blood counts.