Intracavitary Radiation The most common use of this method is in gynecologic tumors, such as carcinoma of the uterus . Specially designed hollow applicators are placed into the uterus under general or spinal anesthesia. X-rays are taken in the operating room to determine correct positioning, and once the placement is satisfactory the operation is ended. After you return to your room, a small plastic tube containing the required number of sources of radioactive isotope of a specific strength are inserted into the hollow applicators. The sources and applicators are left in place for 48 to 72 hours, during which time you have to stay in bed. The seeds deliver the dose over the specified time, and once the dose is reached, the applicator and the sources are removed.
The advantage of this method is that a very high dose of radiation can be delivered to the tumor while the rapid fall-off in the dose gives maximum protection to the surrounding structures.
Intraluminal Radiation Therapy This method has limited use with some tumors in hollow organs like the esophagus and biliary tract. In esophageal carcinoma, for example, a specially designed tube is placed into the opening (lumen) of the esophagus. Then under x-ray visualization—fluoroscopy—several small radioactive sources are placed into the tube opposite the tumor. The tumor receives a high dose of radiation while the dose to the surrounding structures is minimized. Intraluminal therapy is often used in combination with external radiation.
