HIGH DOSE RATE BRACHYTHERAPY
FOR INTERNAL RADIATION
High Dose Rate (HDR) brachytherapy is a specialized type of internal radiation treatment that utilizes a single high activity radiation source that is computer controlled. This single source, or "smart seed", is able to deliver highly precise brachytherapy treatments in a convenient outpatient manner.
As with most brachytherapy procedures, an applicator is first inserted into the body directly into or very close to the tumor. The applicator is then connected to the HDR machine via a transfer tube. The HDR machine is a robot like, computer-controlled afterloader that houses the single highly radioactive Iridium-192 source.
The source is small (1mm x 3mm) and is laser welded to the end of a thin flexible stainless steel cable.
During the 5 - 15 minute HDR brachytherapy treatment, the source travels out of the afterloader into the applicator. It moves thru the applicator in 5mm steps, called dwell positions. The distribution of radiation and dose is determined by which dwell positions the source stops at, and the length of time it dwells there. This ability to vary the dwell positions and dwell times enables the radiation oncologist to optimize the radiation delivery to the tumor and minimize the dose to the normal tissues.
High dose rate brachytherapy is used for cancers of the breast, prostate, lung, head + neck, GI tract, gynecologic cancers, and soft tissue sarcomas.