n HOW WILL RADIATION THERAPY BE DELIVERED TO MY CHILD? There are several types of radiation therapy. Radiation may be given as external beam radiation therapy (from outside the body), brachytherapy (when radioactive material is placed inside the body near the tumor), or systemically (when radioactive material is taken by mouth or through a vein).
External Beam Radiation Therapy (EBRT) EBRT is radiation treatment delivered to a specific area of the body (such as the leg, chest, or brain). Multiple beams of radiation are produced in the radiation machine and then directed at the tumor. The beams are focused to deliver most of the radiation dose to the cancer cells while sparing the normal surrounding tissue. During EBRT, the machine used to deliver radiation does not touch your child. The treatment usually is painless and similar to the way X rays are taken. Side effects generally are limited to the area of the body being treated. EBRT typically is administered in small daily doses called fractions, Monday through Friday, over a course of several weeks. The length of therapy depends on the number of fractions needed to deliver the total radiation dose. In some cases, the radiation dose may be delivered on a different schedule. Your child’s medical team will discuss the treatment schedule with you.
TYPES OF EBRT Three-Dimensional Conformal Radiation Therapy (3D-CRT) incorporates images from CT scans to make 3D pictures of the tumor and the areas around it. This allows the radiation oncologist and team to make the radiation beams match the shape of the tumor. When the beams are more precise, less normal tissue receives radiation, leading to fewer side effects. Intensity-modulated radiation therapy (IMRT) divides radiation beams into many smaller beams. These beams can vary in intensity, and this enables the radiation oncologist to deliver different doses of radiation to specific areas of tumor and surrounding tissues. The goal of IMRT is to deliver a stronger dose of radiation to the tumor while reducing damage done to healthy surrounding tissues. Image-guided radiation therapy (IGRT) uses imaging technology such as X rays, ultrasounds, and CT scans to direct the delivery of radiation. IGRT is most appropriate for tumors that can move during treatment, such as tumors in the lung or liver. Small markers, called fiducials , are placed in or near the tumor before the planning CT scan to track the tumor’s movement. IGRT uses imaging such as CT scans, X rays, and ultrasounds taken just before daily treatments to check for any changes in the condition of the patient or the tumor. These images are compared with CT scans taken during planning. The radiation is directed at the tumor in the most current images, if there is a difference between the planning images and daily image.
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