Brachytherapy is an advanced cancer treatment that can be an alternative to or combined with surgery. Radioactive seeds or sources are placed in or near the tumor itself, giving a high radiation dose to the tumor while reducing the radiation exposure in the surrounding healthy tissues. The term "brachy" is Greek for short distance, and Brachytherapy is radiation therapy given at a short distance: localized, precise, and high-tech. Some of the diseases that are now treated with Brachytherapy include prostate, breast, lung, and tongue cancers. Mesothelioma tumors may also be treated with this technique.

There are two methods by which the radioactive sources can be implanted into the patient's body. The first method is intracavitary treatment and involves passing radioactive sources in special containers through body cavities such as the windpipe, uterus or vagina. The second method is called interstitial treatment. In interstitial treatment the radioactive sources, which are the size of a grain of rice, are injected into the tumor directly via thin catheters. These seeds only give off radiation a few millimeters to kill cancer cells. The seeds can be either permanent or temporary. With permanent seeds the radioactivity of the seeds decays with time while the actual seeds permanently stay within the treatment area. With temporary seeds a series of radiation treatments are given through catheters. A computer can control how long a seed remains in each of the catheters, and therefore is able to control the radiation dose to that specific area. The catheters are then easily pulled out, and no radioactive material is left.

Brachytherapy is usually an outpatient procedure where patients do not need to spend the night and takes only about an hour. General anesthesia is used during the procedure. Generally patients undergoing Brachytherapy experience fewer side effects than less localized forms of radiation treatment.