Evaluation of Radiation Exposure During Sentinel Lymph Node Biopsy in Breast Cancer: A Retrospective Study

Sentinel node biopsy (SNB) is the standard of care for nodal staging in breast cancer. Currently, radioisotope-guided SNB is the standard technique. We have undertaken this study to analyse radiation exposure during SNB for breast cancer over a significant period of time.

The study was conducted over a period of 41 months and included 183 patients. The radioisotope was usually administered the day preceding the surgery at a dose of 40 MBq (±10%), and a lower dose of 20 MBq (±10%) was given if injected on the day of surgery. The radiation exposure was measured by dosimeters worn by the surgeon and surgical assistant.

The surgical procedures performed were mastectomy and SNB (56 patients), wide local excision and SNB (109 patients), and SNB alone (18 patients). The median time interval between the injection and surgery was 19.3 h, and median duration of surgery 93 min. The annual exposure for the surgeon was 0.125 mSv (range 0.01-0.03 mSv) and for the assistant was 0.265 (range 0.01-0.13 mSv).

Contrary to other studies, we found the radiation exposure in the assistant was higher than that in the surgeon and we think this is because the assistant is positioned closer to the injection site during the procedure. However, the cumulative levels of radiation with SNB were very low and significantly below the permissible limits. The timing of injection, type of breast surgery and duration of procedure did not affect the levels of radiation exposure.