High Dose Rate (HDR) Brachytherapy
High dose rate brachytherapy involves temporarily placing a source of radiation within a tumor or cavity of the body. This radiation source moves within a catheter or applicator, and may be stopped at various intervals. This allows the radiation oncologist to conform the radiation to the tumor, to regulate the amount being emitted at each point, and to diminish any exposure to healthy tissue.

Given on an outpatient basis, HDR brachytherapy is used to treat gynecologic, breast, bronchial, esophageal, biliary, and head/neck cancers. Treatments are generally given in three to ten sessions, lasting 5-20 minutes, once a week. These short courses of high doses maximize the effects of the radiation.

There are four primary forms of brachytherapy used by Radiation Oncology Group: intracavitary, intralumenal, interstitial and surface. The procedure is determined by the type of cancer being treated.

Intracavitary brachytherapy is used to treat gynecologic and oral cancers. An applicator, through which the radiation travels, is inserted into a body cavity. With oral cancers, moulds are fabricated to conform to the contours of the oral cavity.

Bronchial, esophageal and biliary cancers may be treated with intralumenal brachytherapy. This involves the insertion of a thin catheter, through which the radiation will travel to the area being treated.

Interstitial therapy requires the insertion of flexible catheters, placed to surround the tumor. These catheters are attached to the HDR machine for the delivery of radiation. Although these catheters will stay in place for the duration of treatment, the radiation itself will only be present during the actual treatment session. When the session is completed, the radiation is retracted into the HDR afterloader, and the patient is free of radiation. Early stage breast tumors and soft tissue sarcomas are examples of cancers which may be interstitially treated.

Surface brachytherapy consists of applying a mould, with catheters running throughout, to the surface of the body.