Radioactive Implants

Radioactive implants are devices that are placed directly within cancerous tissue or tumors, in order to deliver radiation therapy intended to kill cancerous cells.

Purpose

With the use of radioactive implants, the tumor is subjected to radioactive activity over a longer period of time, as compared to external beam therapy.

Precautions

The patient is required to remain in his bed or room during the treatment. During the period of greatest radioactivity (24–72 hours), health care providers will limit the amount of time spent with the patient to that required for essential care.

Description

Interstitial radiation therapy places the sources of radiation directly into the tumor and surrounding structures. Most commonly used in tumors of the head, neck, prostate, and breast, it may also be used in combination with external radiation therapy. The implant may be permanent or removable. A permanent implant of radioactive seeds, such as gold or iodine, is placed directly into the organ. Over several weeks or months, the seeds slowly deliver radiation to the tumor. More commonly used is the removable implant that requires an operation under general anesthesia to place narrow, hollow stainless steel needles through the tumor. Teflon tubes are inserted through the needles, and the needles are then removed. After the patient returns to his room, radioactive seeds are inserted into the tubes in a procedure called afterloading. Once the desired dosage is reached, the tubes and seeds are removed.

Intracavity radiation is often used for gynecologic cancers. Under general or spinal anesthesia, hollow applicators are placed directly inside the affected organ. Correct positioning is confirmed by x rays, and once the patient has returned to her room, a small plastic tube containing the radioactive isotope is inserted into the hollow applicator. The treatment is delivered over 48–72 hours, after which time the applicator and radioactive sources are removed. Very high doses of radiation can be delivered to the tumor, while the rapid removal of the radioactive dose limits damage to the surrounding structures.

Abnormal results

Normal cells are subjected to the effects of radiation; any tissue near the radiation site may be damaged or destroyed. Some side effects are acute and temporary, while others develop over time and may be permanent. Skin reactions, such as redness, itching, flaking, or stripping of the top layer, are usually temporary; long-term effects can include scarring, and changes in texture. Radiation recall is a delayed skin side effect in which the area that had been exposed to radiation becomes irritated or blistered after the patient receives certain chemotherapy.

Following treatment for tumors of the head and neck region, the lining of the mouth and throat can become inflamed or irritated, resulting in a condition known as mucositis or stomatitis. Injury to the salivary glands can decrease saliva production, resulting in a condition known as xerostomia, or dry mouth. There also may be alteration in the patient's taste buds, resulting in decrease or loss of taste sensation (hypogeusia or ageusia), or the presence of unpleasant taste, sometimes described as metallic (dysgeusia). Patients may experience nausea and vomiting as a result of the effect of radiation on the brain. Hair loss (alopecia) may result from radiation's effect on hair follicles.

Radiation's effect on the rapidly growing cells of the gastrointestinal tract may result in diarrhea or abdominal cramping. Pelvic radiation can affect the bowel, bladder, or sexual function. Radiation can also affect production of blood cell components in the bone marrow.