First I'd heard of it!
A typical course of radiation therapy is five days a week (Monday through Friday) for six to seven weeks (usually 35 treatments) on an outpatient basis. Weekend rest breaks allow damaged normal cells to recover. The actual radiation is delivered over two to five minutes; however, each session can last 15 to 30 minutes because of the time required to set up the equipment and position the patient correctly. During this time, the patient receives small amounts of radiation daily to the entire breast and, if necessary, the axillary (underarm) lymph nodes and lymph nodes above the collarbone. Radiation to lymph node areas associated with the breast is usually unnecessary if the lymph nodes are negative. Patients with positive lymph nodes (underarm, above the collar bone, or beneath the breast bone) may or may not need radiation to these lymph node areas, depending on the patient situation and tumor characteristics.
Upon completion of the initial course of radiation, a final, smaller portion of radiation is usually given to the tumor bed (area where the tumor was removed). This final dose is called a "boost or booster dose." There are two methods to deliver booster treatments. The most common method is external delivery (like the initial course) and may last from one to two weeks.
Newer methods of delivering radiation boost are available and are referred to as partial breast irradiation (PBI). PBI targets the radiation to the area of the breast most likely to have a cancer recurrence, the site around the lumpectomy. Three types of PBI treatments are used most commonly:
Multi-catheter brachytherapy (also known as "interstitial brachytherapy")
Balloon catheter brachytherapy (MammoSite® Radiation Therapy System)
Three-dimensional conformal external beam radiation therapy
These methods are all effective and allow the radiation oncologist to deliver a higher total dose of radiation to the area where the tumor was removed.