Low Dose Rate (LDR) Brachytherapy - Seed Implantation

In contrast to external beam radiation treatment that is given on a daily basis, brachytherapy is a type of radiation therapy in which a radioactive source(s) is placed directly into or next to a cancer. Thus, brachytherapy is often referred to as internal radiation.

Radioactive sources used in brachytherapy treatments are most often in the form of small pellets and seeds made from palladium, iodine, cesium or iridium. Once inserted into the cancer, the radiation travels only a matter of millimeters from the source to deliver a lethal dose of radiation to the cancer. The direct placement results in a radiation dose that is very high within the cancer itself while the surrounding healthy organs are spared the effects of radiation. Brachytherapy can be used in the treatment of prostate cancer, breast cancer, gynecologic cancers, some head and neck cancers and occasionally lung cancer.

Low Dose Rate and High Dose Rate Brachytherapy:

The radiation oncologist uses two forms of brachytherapy in the care of cancer patients: low dose rate and high dose rate. The distinction refers to how much radiation the source emits over time. The most common example of low dose rate brachytherapy is a prostate seed implant. Tiny seeds are implanted within the prostate, and a small amount of radiation is delivered to the prostate cancer over a period of months. Because prostate cancer is very slow growing, exposure to radiation over a period of months enhances the destruction of the cancer.

In contrast to low dose rate brachytherapy, high dose rate brachytherapy, known as HDRB, uses a radioactive source to deliver a high dose of radiation in a matter of minutes. HDRB is quickly becoming the preferred option for the treatment of prostate cancer using brachytherapy because of the accuracy and precision of radiation dose delivery, ability to shape the radiation dose to fit the tumor and avoid normal tissue, and fewer urinary, rectal and sexual side effects. Unlike LDRB, HDRB does not have a radiation source that could potentially migration into other organs. For these reasons, the radiation oncologists at the Prostate Cancer Center at Saint Joseph's, currently perform more HDRB procedures than LDRB seed implants.

Seed Implantation

Seed implantation, a type of brachytherapy, is one of the many options used in the treatment of early prostate cancer. The seed implant process is complex. The following is a general overview of what you can expect.

The Pre-Implant Evaluation:

Once a diagnosis of cancer is made by a urologist, all of the treatent options will be discussed. If you are interested in radiation seed implantation, you will be referred to one of our radiation oncologists for consultation.

Since seed implantation is not for everyone, additional tests may be ordered to confirm whether or not you are indeed a candidate. Your radiation oncologist will review all tests results with you in detail.

If seed implantation is recommended, you, your radiation oncologist and your urologist will coordinate plans for the procedure. Occasionally, external beam radiation therapy may be recommended prior to seed implantation. Your radiation oncologist will review the indications for external beam therapy if needed.

Issues to Consider:

• Seed implantation is not for everyone.
• Occasionally, the prostate is too large for a seed implant. Temporary hormonal therapy may be necessary for three to six months to reduce the size of the prostate.
• The prostate may not shrink enough in size while on hormonal therapy. Fortunately, other radiation therapy options, like external beam radiation therapy (EBRT), may be the treatment of choice.

Those who may not be good candidates for seed implantation:

• Patients with severe urinary symptoms at the time of diagnosis may not be ideal candidates because the symptoms can be made worse after implantation.
• Patients with very narrow pelvic bones make seed implantation challenging because the bone structure can prevent optimal seed placement. This phenomenon is known as Pubic Arch Interference.
• Patients who have had a previous transurethral resection of the prostate (TURP) are at increased risk for incontinence when compared to patients who have not had a TURP.

Planning:

First, you will undergo an ultrasound procedure, called a volume study, to assess the size and shape of the prostate gland. The volume study is important as it is used to plan the number and location of the seeds to be implanted throughout the prostate gland. Based on the volume study information, the seeds are ordered from the manufacturer. It may take a week or so to obtain the desired seed strength and number.

The date of the seed implantation procedure is confirmed with the patient, the radiation oncologist, the urologist and the seed manufacturer. The manufacturer ships the seeds the day before the procedure.

Before the Implant:

You will be scheduled for pre-admission testing before the implantation. At that time, you will meet with the anesthesiologist to discuss the best way to deliver anesthesia.

The Implant Procedure:

Pre-operative instructions will be given to you by either the urologist or your radiation oncologist. You are to report to the assigned hospital at the appointed time. Your radiation oncologist, urologist and the ROS physics team perform the implant in the operating room most often under general anesthesia. Ultrasound images of the prostate are obtained while you are asleep. The position and shape of the prostate is confirmed to match the data obtained during the volume study.

Once the position is confirmed, a number of thin needles are placed through the skin and into the prostate gland under ultrasound visualization from a predetermined computer plan. The seeds are inserted into the needles. The needles are then removed, permanently leaving the seeds within the prostate gland. The seeds kill the cancer by releasing radiation over several months. The implant takes about 90 minutes to perform. Most patients go home the same day of the procedure. You will receive discharge instructions from both the urologist and your radiation oncologist.

Follow-up After Implantation:

Approximately two weeks after the implant, you will see your urologist for a follow-up appointment. One month after the implant, you will undergo a limited CT scan of the prostate at radiation oncology office at Saint Joseph's. This important scan is used to identify the number and location of the seeds. Computerized dosimetry is evaluated to assess the actual dose of radiation given to the prostate. Careful life-long follow-up is essential to assess the status of your cancer as well as to evaluate any problems following the seed implant. Follow-up appointments typically alternate between the urologist and your radiation oncologist.

Side Effects:

Most men experience some degree of symptoms for several weeks to months following the implant. The symptoms may include:

• frequent urination
• urgency of urination
• weak urinary stream
• burning with urination
• mild discomfort
• sexual dysfunction

The potential long term effects following the implant may include:

• leaking of urine (incontinence)
• sexual dysfunction (impotency)
• rectal bleeding

Radiation Safety:

You will be given specific radiation safety instructions following the implant. Almost all the radiation is trapped within the prostate gland. You are safe to be around all adults. The items you touch are not radioactive. For the first two months following the implant, you should maintain a distance of six feet from pregnant women. For the first two months following the implant, you should not hold infants on your lap. It is safe for infants to be in the same room with you.

Activity: You may want to avoid strenuous activity for the first few days after the implant. You are encouraged to resume normal activity and diet as soon as you feel ready.

Prostate cancer patients must be actively involved in choosing between several equally effective treatment methods. Patients should be encouraged to research the various options and make their decision taking into account their quality of life concerns along with their work and home life schedules. Although a diagnosis of cancer can be an intimidating experience, the more you are informed about the options available to you, the more equipped you will be to make the decision that is best for you.

We encourage you to contact our Patient Navigator at (678) 843-5665 or renee.sevy@emoryhealthcare.org with any questions regarding LDRB/Seed Implantation at Saint Joseph's. We're here to help.

Information on this page is provided collaboratively by the team at the Prostate Cancer Center at Saint Joseph's and has been medically reviewed by Nancy Wiggers, MD, Radiation Oncologist, 2010. Claims regarding treatment are based on years of clinical experience and industry reported data. The PCC follows American Urological Association and  National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines for the treatment of prostate cancer.

Last Updated: April 22, 2012 (RSH)