Permanent Radioactive Seed Implants: What are They, How do They Work?
What is the radioactive seed implant procedure?
Permanent radioactive seed implants are a form of radiation therapy for prostate cancer. The terms "brachytherapy" or "internal radiation therapy" might also be used to describe this procedure.
During the procedure, radioactive (iodine-125 or I-125) seeds are implanted into the prostate gland using ultrasound guidance. The number of seeds and where they are placed is determined by a computer-generated treatment plan tailored for each patient. About 100 seeds are commonly implanted.
The implants remain in place permanently, and become biologically inert (inactive) after about 10 months. This technique allows a high dose of radiation to be delivered to the prostate with limited damage to surrounding tissues.
Compared to external radiation, which requires 7 to 7 ½ weeks of daily treatments, convenience is a major advantage of this treatment option because it is a single outpatient procedure.
Who is eligible for this procedure?
Permanent implants are relatively low-energy sources, and therefore have limited tissue penetration. A well-done implant will treat the prostate and the surrounding few millimeters of adjacent tissue.
Therefore, the best candidates for this procedure are patients who have a cancer that is contained within or near the prostate. Patients with prostate cancer that is invading nearby structures like the bladder or rectum are not appropriate for this technique.