Prostate Seed Implant
A Patient's Guide
This photo illustrates the size of the prostate seed implants in comparison to a penny.
Prostate Seed Implant (PSI) is a form of internal radiation therapy (brachytherapy) in which radioactive "seeds" (metallic particles about the size of rice) are implanted into the prostate gland. The seeds contain radioactive iodine or palladium which will treat the tumor site over the course of several weeks. PSI requires careful planning, and side effects are possible.
Not all men are appropriate for PSI. Your radiation oncologist will discuss specific criteria with you to see if you are eligible. If PSI is deemed appropriate and warranted for your case, the following procedure will apply.
Ultrasound Volume Study
The PSI process begins with an ultrasound volume study, a 3D planning procedure used to determine very accurate measurements of the patient's prostate gland size and shape. This information is used to determine how many seeds will be needed and exactly where those seeds should be placed for optimal results.
The study is performed in the Radiation Oncology Department approximately one month prior to the actual implantation. Patients lie on a table with their legs supported above them. A probe is then inserted into the rectum to provide the ultrasound image. Detailed instructions in preparation for the volume study will be given to you prior to your appointment.
Seed Implantation
The seed insertion itself is performed in the operating room on an outpatient basis. Patients lie in the same position as they did during the volume study and are then draped, anesthetized and prepped with an anti-bacterial solution. The seeds are inserted with a needle through the area between the scrotum and rectum. The anesthesia ensures a pain-free experience.
This radiograph image depicts the placement of the prostate seed implants.
Doctors follow a specific pattern for needle insertion and take special care to ensure each needle is placed in exactly the right place before depositing the seeds. Seed locations are verified with x-rays of the pelvis at the completion of the procedure.
The seeds themselves have been special-ordered for the surgery based on the results of your ultrasound volume study. Approximately 80-100 seeds will be implanted in this manner throughout the prostate gland. Patients usually go home the same day, though the doctor might recommend staying overnight. In either case, you may be given an oral antibiotic to help prevent infection.
Side Effects
Most patients experience some side effects from PSI. These include slight bleeding beneath the scrotum, blood in the urine and bruising and tenderness between the legs due to the insertion of the seeds. Later side effects may include frequent urination, burning with urination, a sense of urgency to urinate and a weaker urinary stream. These side effects are caused by the radiation emitted from the seeds. Your doctor will provide you with detailed information about side effects and what you can do to lessen them.
Post-Implant Care
In general, PSI requires less recovery time than surgery and fewer trips to the cancer center than external beam radiation therapy. Once the seeds are inserted into the prostate gland, they are not removed. A CAT scan is performed one month after the operation to assure the seeds are distributed throughout the prostate gland, followed by routine follow-up.
How the Radiation Works
Iodine and palladium lose their radioactivity fairly rapidly and emit a relatively low amount of radioactive energy. As a result, the radiation is almost completely absorbed by the tissue very near the seeds. The radiation that is emitted from the body is so low that it is barely detectable. In fact, bodily wastes (urine and stools) are NOT radioactive, and neither are any items the person touches and uses.
Precautions
Even so, there are a few precautions patients are asked to consider. For example, patients are asked not to hold small children on their laps and to avoid prolonged close contact with any women who are or possibly could be pregnant for two months after the implantation. Sexual intercourse should also be avoided for the first four weeks. Your physician will explain all of the precautions to you and provide you with detailed information about the procedure itself along with any special care or potential side effects it may entail.