Brachytherapy (brake-ee-therapy) is the oldest type of radiation treatment and was used well before the development of modern day linear accelerators that are used for external beam radiation therapy. It is used in the management of almost all cancers but most commonly in the treatment of gynecologic, breast, and prostate cancers.
The greatest advantage of brachytherapy is that the treatment is from “inside out” as opposed to “outside in”. This means that instead of radiation traveling through normal tissues that don’t need to be exposed in order to reach a target located in the body brachytherapy allows a small radiation source to be brought directly to and/or near the target. This allows the greatest amount of radiation dose to be concentrated where it is needed most and the intensity of the radiation falls off very quickly thereby minimizing unnecessary radiation dose to your normal tissues.
Here at UCLA we have extensive experience in brachytherapy and in particular High Dose Rate (HDR) brachytherapy. With HDR brachytherapy a single tiny (4.5 mm diameter) radioactive source of Iridium-192 is laser welded to the end of a thin, flexible stainless steel cable and is housed in a device called an afterloader. This computer guided afterloader directs the source into the treatment catheters or applicator that has been placed in the patient by the brachytherapy physicians. The source travels through each catheter in 5 mm steps, called “dwell” positions. The distribution of the radiation dose is determined by the dwell positions the source stops at and the length of time it dwells there. This ability to vary the dwell times is like having an unlimited choice of source strengths. This level of control is possible only with HDR. After the HDR treatment the source retracts into the afterloader. The patient is no longer radioactive. Finally, because the afterloader controls the radiation source, radiation exposure to the physicians, hospital staff and family members is eliminated.
On the left is an example of what a remote afterloader looks like. The middle picture shows what the inside of the afterloader looks like with the cover off. The image on the right shows how a small radiation source is welded onto the end of a cable. The motor in the afterloader pushes and pulls this cable in and out of the treatment channels.
Recently we’ve acquired the most technologically advanced HDR remote afterloader called the Flexitron. We are currently one of only a few centers in the United States to have this afterloader.