Radiation Therapy Technique for Breast Radiation

• The first step is the simulation. The patient lies on an Xray table with a fluoroscope and the planned areas of radiation are setup. Xray pictures are obtained to ensure that the radiation field includes all the necessary parts of the breast, chest wall and nodes that need to be included, but avoids hitting areas that should be avoided or limited (e.g. lungs and heart.) Sometime a body cast is set up (alphacradle) or special bocks are designed and cut that will be inserted into the machine to block out areas that need to be protected.
• The radiation treatments are given daily (Monday through Friday) and are designed to treat the entire breast (and sometimes the lymph nodes.) The dose to the breast is generally 4500 to 5000cGy (given at 180 to 200cGy per day) and takes approximately 5 weeks. This amount of radiation is considered a large enough dose that it will sterilize (kill off) any microscopic sized cells that may be spread or exist anywhere in the breast
• After the whole breast has received the dose as described, an extra amount radiation (see booster dose) is often given to the region where the cancer started. This dose is usually 1000 to 1500cGy and if often given with electron beam irradiation (which has a limited depth of penetration.) This extra amount of radiation if though necessary to sterilize a larger volume of cancer cells, based on the possibility that this area of the breast may harbor more cancer cells. The necessity of this booster treatment is related to the size of the original tumor, the type of surgery performed, and the surgical margins on the pathology report. The scientific evidence on the benefit or necessity for booster radiation is somewhat inconclusive.

the areas that are to be treated with radiation are marked on the skin and may include not just the breast but the lymph node areas that surround the breast