• A permanent implant involves small radioactive seeds such as gold or iodine placed directly into the affected organ. I-125 seeds, for example, are used for prostate cancer. Over several weeks or months, the seeds slowly deliver a specific dose of radiation to the tumor .
• A removable implant is the most common method of interstitial radiation therapy . The operation, usually carried out under general anesthesia, involves placing narrow, hollow stainless steel needles through the tumor. Once the placement seems satisfactory, Teflon tubes are inserted through the needles and the needles are then removed, leaving the tubes in place. The operation is then terminated and you return to your room, where a small ribbon of radioactive seeds will be inserted into the tubes in a procedure called afterloading.
With computerized treatment planning, the specific strength of each seed can be selected, thereby providing the desired dose to the tumor volume over a specific period. Once the dose is reached, the tubes and the seeds are removed. This type of implant is commonly used for tumors of the head and neck or as a boost after external beam radiation of breast cancer after a lumpectomy .
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
