Retinoblastoma Patient & Family Handbook

RADIATION Radiation therapy uses high energy x-rays to kill cancer cells and can be effective in treating retinoblastoma. It is used either in combination with other therapies or after other therapies have failed. There are two types of radiation therapy used for retinoblastoma: brachytherapy and external beam radiation therapy. Plaque radiotherapy is a form of brachytherapy that uses a custom designed plaque (that is placed directly around the affected area of the eye. The plaque is a thin piece of metal (usually gold) that has radioactive seeds on one side of it. The side of the plaque with the seeds faces the eye. The radioactive seeds deliver the radiation to the tumor site. The plaque helps protect surrounding tissue from the radiation. It is sewn to the skin that covers the eye while the child is under general anesthesia in the operating room. The plaque remains in place for 3–5 days, depending on the dose of radiation that needs to be delivered, and then is removed while the child is under general anesthesia in the operating room. This form of treatment delivers concentrated radiation therapy only to the tumor without affecting the rest of the eye or the eye socket (bone). The child remains in the hospital during this process. External beam radiation therapy (EBRT) focuses radiation therapy on the cancer cells from a machine outside the body. The radiation dose is calculated by a radiation oncologist who will plan how much radiation therapy is needed and how long it will take. Newer types of radiation therapy are able to target the cancer cells more precisely and spare surrounding tissue. Two types of EBRT radiation therapy include: (1) IMRT (intensity modulated radiation therapy) which allows the doctor to aim the radiation at different angles of the tumor while using different strengths of radiation that is needed, and (2) Proton beam iradiation therapy. With Proton beam therapy, the radiation machine delivers protons (tiny invisible charged particles) directly to the tumor. Depending on the age of the child, anesthesia may be required with each treatment to ensure that the child stays in the correct position which is crucial to the delivery of the radiation to the tumor area.