High-Dose Rate Brachytherapy
Brachtherapy is a form of radiation therapy that is delivered from inside the body at the tumor site rather than from an external source such as from a linear accelerator. Brachytherapy delivers a higher radiation dose to the tumor bed, while sparing normal tissue. Many people are familiar with this technology in the form of radioactive seed implant therapy for prostate and gynecological cancers in which several low-dose radioactive sources are used.
How is HDR different?
HDR brachytherapy uses a single, tiny highly radioactive source that is laser welded to the end of a thin, flexible stainless steel cable. With HDR brachytherapy, the radioactive source does not stay inside the body permanently. Rather, this radioactive source travels to the tumor site through a thin, surgically-placed tube or catheter. A sophisticated, computerized device called an afterloader (shown right) houses the source and sends it out into the treatment catheters or applicators. Because of the high radioactivity of the sources used, treatment time is reduced to minutes instead of days. High dose rate treatments are short (usually a few minutes) and result in less discomfort than other types of radiation therapy. And because radioactive materials are not left in your body, you can resume normal activity right away.
What are the uses for HDR?
Among the more common applications of HDR are gynecologic and breast brachytherapy.
Using HDR for gynecologic brachytherapy, eliminates the need for patient hospitalization during treatment. Care is provided in the outpatient setting and is given over 3 to 6 treatments.
Today, more and more women with early-stage breast cancer are able to treat their cancer effectively and preserve their breasts through an option called breast conservation therapy (BCT). This treatment includes the removal of the cancerous tumor, which is called a lumpectomy. The lumpectomy is generally followed by 7 weeks of whole breast external beam radiation therapy. This combination of surgery and radiation works well to prevent local recurrence of the tumor.
Despite the proven success of this approach, some women are turning to a promising alternative: accelerated partial breast radiation. HDR brachytherapy delivers accelerated partial breast radiation therapy, treating the area around a lumpectomy with a highly localized dose of radiation over a period of about 5 days. Physicians deliver a precisely targeted dose to tissues most at risk for recurrence of tumor while limiting the radiation to the lungs and opposite breast.
At Rush-Copley, surgeons and radiation oncologists work together very closely to provide your care using a system called the MammoSite Radiaiton Therapy System. The MammoSite is a small, soft balloon attached to a thin catheter (tube) that is placed inside the lumpectomy cavity (the space left after the tumor is removed) by your surgeon. A tiny radioactive source (seed) is placed within the balloon by a computer-controlled machine operated by your radiation oncologist.
View a demonstration of this procedure
What are the benefits of HDR?
- Improved accuracy and precision of radiation dose delivery
- Knowledge of radiation dose distribution before treatment is given
- Ability to shape the radiation dose to fit the tumor
- Control of adjacent organ doses resulting in fewer side effects
- No radiation exposure to other persons
- The treatment course is days rather than weeks to months (as required for permanent seeds or external beam)
What is the process for a typical HDR treatment?
Step 1: Implant placement
Your physician will place what is called an intracavitary implant: an applicator is inserted into a body cavity to reach the tumor. Intracavitary implants may be placed at the time of surgery (lumpectomy) or may occur post-surgery. All implants are done on an out-patient basis. Local anesthesia and/or conscious sedation is all that is required.
Step 2: Simulation
After the implant has been placed, either CT or special x-ray films are taken by the radiation therapists to determine the exact location of the implant in the body and the relationship to adjacent organs. The therapists' expertise in taking these films assures that the implant and nearby organs are visualized clearly. The physician reviews these films and makes final adjustments to the implant if necessary.
Step 3: Dosimetry
The CT images or films are given to the dosimetrist to enter into the treatment planning computer. The computer does the initial calculation but it is the dosimetrist who "fine tunes" or customizes the radiation doses to conform to the target volume while minimizing the doses to the nearby normal tissues. After the treatment plan has been approved by the physician, the computer transfers the treatment plan instructions to the HDR remote afterloader.
Step 4: Treatment
Before each treatment, the exact location of the implant is verified on our simulator. The patient is then moved into the brachytherapy treatment room. The ends of the applicator or treatment catheters that protrude outside the body are connected to "transfer" tubes which are then connected to the afterloader. The programmed instructions tell the afterloader where to direct the source and how long the source will stay in each dwell position. The patient is alone in the treatment room while the treatment is being given, but the therapists and nurses are continually monitoring the patient through an intercom and closed circuit TV monitors. The time the source spends in the implant is about 10 to 15 minutes. The entire treatment process takes about 30-60 minutes. These time estimates will vary depending on the size and complexity of the implant and on the activity of the source. When the treatment is completed, the radiation source is retracted back into the HDR afterloader. There is no radiation left behind in the patient.
Step 5: Implant Removal
After the treatment(s) have been given, the implant is removed. Intracavitary applicators are simple to remove and the patient goes home soon after removal. Post- implant skin care instructions are given by the nurses before the patient leaves. A date for a follow-up appointment will also be given.
Step 6: Follow-up
It is important that the patient keep us informed as to their recovery, any side effects, etc. We provide a thorough patient follow-up, which is how we assess the efficacy of our HDR treatments.