Introduction
Brachytherapy, or internal radiation, comes from the Greek word brachy, which means short. Unlike external beam radiation therapy, which delivers a high energy dose of radiation from outside the body, Brachytherapy is a low energy type of radiation therapy in which small radioactive devices are placed in direct contact with the cancerous tissue being treated. These radioactive devices, called seeds or sources, are permanently implanted inside your tumor. This means low energy radiation is deposited directly in the prostate gland to achieve the desired therapeutic effect. This minimizes radiation exposure to healthy surrounding tissue.
On average, 60 to 120 seeds, each smaller than a grain of rice, are placed in a predetermined pattern specific to your prostate gland, and remain there as permanent implants. The low energy isotopes used in these seeds lose their radioactivity quickly. Depending on the isotope used this effective life can occur over one to three months. The seeds will continue to decay so that the level of radiation becomes essentially undetectable. Using computer technology, your doctor will decide during pre-treatment planning the number, placement and type of isotope best suited for your treatment.
Pre-planning
Prior to your implant you will be scheduled for a pre-implant planning study. This usually involves a planning ultrasound study but can involve other imaging techniques such as CT scan. Your prostate gland is measured in small increments and the images are downloaded into a treatment planning computer. This data will be used to customize the implant for you, providing the doctor with the exact size, shape and location of your prostate. Your planning team, which includes a medical physicist and your radiation oncologist, will then be able to determine how many radioactive sources are necessary and where they should be placed.
Implantation
You will need to go on a special diet the day before your implant. You will also be instructed on medications that you will need to take to clean out the lower bowel. You should not eat or drink anything after midnight on the day of your implant. You will be given specific instructions for this preparation prior to your implant.
On the day of the implant, you will be instructed what time to report to the outpatient surgery center. You will be placed under spinal or general anesthesia. After anesthesia has been induced, the ultrasound probe will be inserted into your rectum. The probe will allow your doctors to visualize your prostate gland throughout the implant procedure. Then, needles containing the prostate seeds will be inserted through the skin of the perineum (the area between the scrotum and anus). The seeds are small and are left in place permanently.
Your Urologist and Radiation Oncologist will both participate in your implant. The implant takes approximately one hour. At the end of this procedure your Urologist will often perform a cystoscopy to visualize the bladder and make sure that your urinary tract (the urethra) is clear. A catheter (a small rubber tube inserted through the penis into the bladder to drain urine, usually into a small plastic bag strapped to the leg under the pants) will then be placed. You will be discharged a few hours later and you will be sent home the same day as the implant with the catheter in place. You will be given instructions on how to remove the catheter the next morning.
Possible Side Effects
After your implantation, you should expect slight bleeding, bruising and tenderness at your implantation site, as well as bleeding when you urinate. These side effects should subside after a few days. You may also experience frequent urination, urinary urgency, burning with urination and a weaker urinary stream. Your physicians can prescribe medications to help with these symptoms. In some cases urinary obstruction may develop and the catheter will need to be reinserted.
Seed implantation rarely has any serious impact on bowel function. In the first few weeks after the implant, about 10% of men report having 2 or 3 normal bowel movements a day instead of their usual 1 a day. Some say they have difficulty sensing a bowel movement and will sit when urinating as a precaution. These effects, if they occur, only last a few weeks and then bowel movements return to normal for almost everybody.
If sexual activity is attempted soon after the implant, be prepared for a burning pain lasting for a few minutes after ejaculation and blood in the semen.
There are also some possible long-term side effects. Impotence can result as well as chronic urinary irritation. In rare instances bowel or bladder injury can occur. Your Radiation Oncologist will discuss these potential side effects with you.
Radiation Precautions
After your seeds have been implanted there are certain precautions that you need to take due to the radiation in your body. For at least the first two months after your implant:
- Do not let children sit in your lap
- Avoid prolonged contact with pregnant women closer than 6 feet
- Use a condom during intercourse because you may discharge seeds in your ejaculate
Following the treatment from the Brachytherapy seeds, they will remain in your body. Radiation decays over time and depending on the isotope used this effective life can occur over one to three months. The seeds will continue to decay so that the level of radiation becomes essentially undetectable. Although the seeds are designed to stay in place, after implantation some may be carried out of your body through your urine flow. The loss of these seeds should not raise alarm, but you should follow your doctor’s recommendation on how to retrieve the seeds. Your doctor will explain these and other precautions at the time of your procedure.
Types of Radioactive Seeds
Your Radiation Oncologist will discuss the type of radioactive seeds that will be used for your implant. There are two isotopes commonly used. Either Radioactive Iodine (I-125) or Palladium (Pd-103) will be used. Your doctor will discuss which of these is best suited for treatment of your disease. In addition, we will sometimes use sources that are linked together to insure correct positioning in and around the gland.
Follow-up
You will be given follow-up appointments with both your Urologist and Radiation Oncologist. At your first return visit with the Radiation Oncologist you will likely undergo a CT scan through the implant region. In the next few days following the scan our Medical Physicists will run a post-implant computer plan to make sure that the seeds are properly positioned for the treatment of your cancer.