Brachytherapy is a method of delivering radiation to tumors by placing radioactive sources in close proximity to the tumor (“intracavitary” brachytherapy) or within the tumor itself (“interstitial brachytherapy).
Derived from the Ancient Greek word brachios meaning “short”, brachytherapy is sometimes referred to as “internal” radiation therapy or an “implant”.
Since a radiation source is placed close to or directly within the tumor, higher radiation doses can be typically delivered than with external beam radiotherapy. Moreover, rapid dose falloff around the sources means that less radiation is delivered to surrounding normal tissues.
How is Brachytherapy Performed?
Brachytherapy is most commonly performed with either high-dose-rate (HDR) or low-dose-rate (LDR) techniques. LDR approaches predominantly for much of the last century and have been used in a wide variety of tumor sites, notably cervical and uterine cancers.
In gynecology patients undergoing LDR brachytherapy, an applicator is placed within the cervix/uterus with the patient under general anesthesia in the Operating Room. Radioactive sources, typically Cesium-137, are later inserted into the applicator (“after-loaded”) once the patient is transferred to a shielded hospital room.
LDR patients are kept at strict bedrest for 1-3 days, with the procedure typically repeated in 1-2 weeks depending on the dose required and site treated.
LDR Brachytherapy, Cervical Cancer
High Dose Rate (HDR) Brachytherapy
More recently, HDR have all but replaced LDR techniques in most tumor sites. Unlike LDR, HDR is an outpatient procedure avoiding the need for general anesthesia and a prolonged hospital stay at bedrest. This is particularly appealing in the elderly and in patients with multiple medical problems.
HDR Brachytherapy uses high activity Iridium-192 sources, allowing treatment to be delivered within minutes as opposed to several days. HDR is performed in a special HDR Suite within the Department of Radiation Oncology. Between treatments, the Iridium source is stored in a shielded device and is delivered under computer control.
An important benefit to HDR brachytherapy is that the source position can be precisely adjusted, allowing the Radiation Oncologist to create customized dose distributions based on the individual patient’s anatomy and tumor.
HDR Brachytherapy is the preferred method of Brachytherapy at UCSD and is used in a wide variety of disease sites including cervical cancer, endometrial (uterine) cancer, and breast cancer. State-of-the-art HDR afterloading and CT-based computerized Treatment Planning systems are used to deliver HDR brachytherapy.
Other Tumor Sites
Brachytherapy is also used in the treatment of brain tumors (Gliasite), ocular tumors (Eye Plaques) and for palliation in obstructive lung and head/neck tumors (endobronchial brachytherapy).
Interested in learning more about Brachytherapy?
Check out the American Brachytherapy Society (ABS) website. It contains additional patient-oriented information, helpful links, and other patient resources