BRACHYTHERAPY

High-Dose Rate Brachytherapy

Brachytherapy is a method by which a radioactive source is placed in the part of the body that is to be treated and a high dose of radiation is given to a very limited area. The advantage of brachytherapy over external beam irradiation is that the dose is concentrated in a small area. The volume of tissue that is treated is limited, and the surrounding normal tissue receives a lower dose of radiation than it would if external beam irradiation was used instead. Brachytherapy can either be given with conventional low-dose sources, where the treatment takes place over several days in the hospital, or it can be given on an outpatient basis using a high-dose-rate (HDR) brachytherapy machine.

There is a long track record for use of low-dose-rate brachytherapy for a variety of tumors such as head and neck cancer, breast cancer, gynecologic cancer, and prostate cancer. HDR brachytherapy has also been used in these situations, but there is less experience with use of HDR brachytherapy compared with low-dose-rate brachytherapy. In some situations, however, HDR brachytherapy is as effective as low-dose-rate brachytherapy and has a very low risk of radiation injury. In these instances, it may be preferable to the low dose treatment because HDR brachytherapy can be given in 2 or 3 outpatient treatments. The actual treatment delivery lasts about 5 to 10 minutes, while the overall visit to the radiation therapy department lasts 30 minutes to 1 hour, in contrast to a hospitalization that might take several days for low-dose-rate brachytherapy.

An HDR brachytherapy treatment generally involves a short visit to the radiation oncology department, where a device or holder is placed into the area to be treated. Thereafter, the device is connected to an HDR brachytherapy machine, and a small, but intense, radiation source (a radioactive "seed") is loaded into it. A high dose of radiation is given over treatment time that varies somewhere in the range of 5 to 10 minutes, depending on the intensity of the source. The radioactive seed is then withdrawn back into the brachytherapy machine, which then is disconnected from the device that was placed into the tumor.  The device is removed and the patient is discharged from the department to return a week or two later for a second or third treatment, depending on the number of treatments prescribed.

The advantages of HDR brachytherapy compared with low-dose-rate treatment are that it is more convenient and less expensive. An additional advantage is that there is minimal, if any, associated risk of deep vein thrombosis or thrombophlebitis, which may occur if a patient is placed in bed for several days for a procedure such as a low-dose-rate gynecologic implant.