Combined High-dose-rate (HDR) Brachytherapy and External Beam Radiation Therapy (EBRT)
Combined HDR brachytherapy and EBRT is used for patients with locally more advanced disease within or around the prostate, those with higher PSA levels or higher pathology (Gleason 8-10) grade. Delivery of EBRT expands the area of treatment beyond the prostate into other regions of the pelvis where microscopic deposits of disease may be present but undetected. Combined HDR and EBRT therapy patients undergo two HDR implants a week apart with two HDR radiation treatments (also called fractions) per implant for a total of four HDR treatments. Approximately 2 weeks later a short (4-5 weeks) course of EBRT (Monday through Friday) is given.
UCLA’s Department of Radiation Oncology’s published results on patients followed for 10 years are among the best reported in the literature. They have shown 90% clinical control of disease and high rates of freedom from PSA progression (a rising PSA) that vary according to the severity of disease.
HDR brachytherapy procedure
- On the day of the actual procedure the patient is taken to the operating room and given spinal anesthesia (numbs the patient from the waist down) as well as some sedation.
- The patient’s legs are place in stirrups and the pelvis is positioned by the physician to access the perineum (the space between the scrotum and anus).
- The physician then uses a template to help direct the treatment tubes called “flexiguides” in and around the prostate. This template has pre-drilled holes arranged in two concentric circles. This circular distribution conforms better to the natural shape of the prostate. The template is held in one hand, while the flexiguides are inserted with the other. Holding the template, rather than having it clamped to the table as in the fixed template technique, allows the physician to tip and angle the template, resulting in more control over where they can place the flexiguides. This is a major advantage as it allows the physician to flare the flexiguides to encompass larger prostates, extracapsular extension, or seminal vesicle involvement.
Below is an example of the standard template that we use for prostate brachytherapy here at UCLA.
Once the flexiguides are in position the template is sutured to the perineum to stabilize the implant.
A camera is used to look into the bladder to ensure appropriate placement of the flexiguides and then a foley catheter is left in the bladder.
After a brief stay in the recovery room the patient has a CT simulation where the placement of the flexiguides is confirmed. Once the images of the implant are obtained the patient waits for the customized treatment plan to be generated.
After the physician approves the treatment plan the patient is moved to the HDR treatment room where the protruding ends of the flexiguides are connected to transfer tubes, which in turn are connected to the HDR machine. Although the patient is alone in the treatment room, he is constantly monitored via a camera and intercom. The patient will hear the afterloader click and a motor running as the radiation source is directed into each of the flexiguides. The Iridium-192 source delivers the radiation dose in about 15 minutes. After the treatment, the source withdraws into the HDR machine. The patient at this point does not have any radiation precautions.
Patients will have an overnight stay and spend the night in the outpatient surgery center. The next morning, the second treatment is given. This second treatment requires much less time because the simulation and treatment planning process does not need to be done again. Just a pre-treatment CT scan is performed to verify that the implant hasn’t moved overnight and then the patient is treated. After the final treatment the implant and foley catheter are removed and we make sure the patient can urinate on his own.