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.
High Dose Rate (HDR) brachytherapy involves two treatments that place an intense radiation source directly in or around a cancerous tumor for a few seconds at a time. Computer planning and control allows for precise delivery of radiation doses.
HDR therapy offers many advantages over other radiation therapy techniques for prostate cancer. It allows for more intense and pinpointed treatment than external beam radiation therapy alone. HDR also has several advantages over low-dose permanent seed implant brachytherapy techniques. For example, with HDR, the amount of radiation in each of the implanted catheters can be adjusted after the implant procedure resulting in a radiation pattern that can be refined as needed. There is not a risk of seed migration and there is no radiation exposure to other people.
Catheter Placement
Catheter placement is a surgical procedure, for which patients are given a spinal or light general anesthetic. 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. 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. Catheter placement involves using the ultrasound to guide the insertion of 14 to 20, flexible, small-diameter catheters into the prostate through the skin of the perineum (the area between the scrotum and anus). The radiation source will be delivered to the prostate through these catheters. This portion of the procedure takes 30 minutes to one hour.
After the anesthesia wears off, patients may be aware of a plastic template that has been placed next to the perineum to keep the catheters in place after the procedure. Catheter placement takes place in an outpatient surgery center and you will then be transported to the treatment center for the radiation treatment. You will wake up on a special mattress that allows access to the catheters and will stay in bed until the catheters are removed later the same day.
Planning Radiation Treatment
After catheter insertion, the process of planning the radiation treatment begins. A CT scan will be obtained of the prostate. Each of the catheters are identified and their position may be adjusted slightly based on the CT scan. This scan also identifies the exact location of the prostate, the course of the urethra, as well as the position of the bladder and rectum. This information is entered into the computerized treatment planning system. This planning process will determine the appropriate dose of radiation for each catheter, which will allow precise planning of the radiation dose to the prostate.
Delivering HDR Treatment
Once an individual’s treatment plan has been determined, the patient is taken to a special treatment room, where each of the implanted catheters is attached to the HDR machine via connecting cables. The computer-controlled HDR machine transfers a very intense radioactive source through each catheter according to the individual’s treatment plan. This treatment is painless and takes only 10 to 15 minutes. During treatment, you will hear a clicking sound as the intense radiation source is moved through each catheter.
Once the treatment is completed the catheters as well as the template near the perineum will be removed and you will go be discharged to home. The catheter will also be removed from the bladder, but sometimes you may go home with the catheter in place and be instructed on removing the catheter the next morning.
Generally two implants are performed approximately one week apart. As part of the overall treatment plan a course of daily radiation treatments will be delivered. This is usually a series of daily treatments delivered on a Monday through Friday basis for approximately five weeks.
Side Effects
Most men experience frequent urination and blood in their urine the first few days following the implant. Mild tenderness, swelling and bruising of the perineum often occurs. To date, no serious radiation injuries to the rectum and bladder have been observed as a result of this treatment; although there is no guarantee that they may not occur.
Temporary impotency is usually a side effect following the HDR implant. The permanent effect of radiation therapy on potency is extremely difficult to determine. In general, however, an estimated 60 to 70 percent of men who were fully potent prior to treatment will regain potency after treatment. The HDR treatment regimen was not designed with potency preservation in mind, but rather to deliver optimal radiation to the prostate to successfully treat the cancer. Interventions such as the medication Viagra are often successful in treating impotence.
During daily external beam radiation treatment, most patients experience mild to moderate urinary frequency and burning. Medications are available to help relieve this condition. Irritation may also occur in the rectal area resulting in increased intestinal gas and soft bowel movements. Following external beam radiation treatment, any rectal and urinary symptoms typically subside within four to six weeks. Fatigue can also be a side effect of daily radiation. While some may find it necessary to reduce workloads and increase rest periods, most patients continue their regular routine, including work and exercise.
Treatment Follow-up
Regular follow-up appointments with your radiation oncologist and urologist will be recommended. Regular rectal examinations and PSA’s are also essential follow-up steps.
Advantages of HDR Brachytherapy for Prostate Cancer:
- Preservation of organ structure and function
- Few side effects
- Excellent coverage of microscopic extension of cancer
- Knowledge of radiation dose distribution before treatment is given
- Accuracy and precision of tumor-specific radiation dose delivery
- Optimal radiation dose uniformity (avoids hot and cold spots)
- No radiation source (seed) migration into other organs
- No radiation exposure to other people.