Radiation Therapy Procedures

One form of radiation therapy for cancer and other diseases is the administration (oral or by injection) of radioactive materials to treat various diseases. The most common of these is oral administration of radioactive iodine, which is used to treat hyperthyroidism or cancer of the thyroid. In another form of therapy, radioactive seeds can be placed into various organs and tissues to treat cancer. And finally, radiation emitted from large machines (linear accelerators or teletherapy units) can be used to treat cancer and other diseases. Before any of these procedures, physicians will take the pregnancy status of the patient into consideration, so in nearly all instances these uses of radiation will not occur when a woman is pregnant. Physicians who believe that delaying the procedure until the child is born would be a significant risk to the mother may decide to proceed and will share with the patient the possible risks of radiation exposure to the unborn child.

Occasionally, radioactive iodine for the treatment of hyperthyroidism or cancer of the thyroid is administered to a woman who may not yet know she is pregnant. In these instances, it is essential that the exposure to the unborn child be determined before any counseling can be provided. It is recommended that this determination be obtained from a health or medical physicist, a nuclear medicine physician, or a radiation oncologist associated with the institution where the procedure took place.  

Since radiation treatment for cancer involves quite high doses of radiation, in the thousands of rem, it is very likely that the unborn child will be affected if radiation therapy is initiated during pregnancy. In this case, if the mother is receiving radiation therapy of the lower abdomen for cancer treatment, the unborn child may not survive. When exposures occur later in gestation, unborn-child sensitivity may be less and the unborn child might survive, but there is still concern about long-term radiation effects.

It is possible that even with radiation therapy to parts of the body other than the abdomen, the unborn child might receive an exposure increasing the risk of biological effects. Again, it is essential that the exposure to the unborn child be determined before any counseling can be provided. It is recommended that this determination be obtained from the health or medical physicist, a nuclear medicine physician, or a radiation oncologist associated with the institution where the procedure is to take place or has occurred.