Levothyroxine is a medication used in this trial to help protect the thyroid gland during radiation therapy. It works by suppressing the production of thyroid-stimulating hormone (TSH), which may help reduce the risk of developing hypothyroidism, a condition where the thyroid does not produce enough hormones. This medication is being tested to see if it can lower the chances of hypothyroidism in patients receiving radiation treatment for medulloblastoma, Hodgkin lymphoma, and non-Hodgkin lymphoma.

Hodgkin Lymphoma – This is a type of cancer that originates in the lymphatic system, which is part of the immune system. It is characterized by the presence of Reed-Sternberg cells, a specific type of abnormal cell. The disease often begins in the lymph nodes and can spread to other parts of the body. Symptoms may include painless swelling of lymph nodes, fever, night sweats, and weight loss. As the disease progresses, it can affect the body’s ability to fight infections.

Non-Hodgkin Lymphoma – This is a diverse group of blood cancers that include any kind of lymphoma except Hodgkin’s lymphomas. It typically starts in the lymph nodes but can also affect other organs. The disease is characterized by the uncontrolled growth of lymphocytes, a type of white blood cell. Symptoms can include swollen lymph nodes, fever, night sweats, and unexplained weight loss. The progression can vary greatly depending on the specific type and stage of the disease.

Medulloblastoma – This is a type of brain cancer that is most common in children. It originates in the cerebellum, the part of the brain that controls balance and coordination. The tumor can spread to other parts of the brain and spinal cord through the cerebrospinal fluid. Symptoms may include headaches, nausea, vomiting, and problems with coordination or balance. As the tumor grows, it can increase pressure within the skull, leading to more severe symptoms.