Sentinel Node Navigation Surgery with 99mTc-tin Colloid in Breast Cancer: Radiation Safety Considerations

Abstract

Purpose: The incident at the Fukushima Daiichi nuclear power station in 2011 has again raised concerns with the public regarding radiation exposure, especially so in medical workers and patients undergoing treatment involving the use of radiation. Radioisotopes are currently used during sentinel node navigation surgery (SNNS) in operating rooms without radiation monitoring. To re-evaluate the safety issues, the potential effective dose (Epoten) from 99m Tc-tin (-Sn) colloid in breast cancer surgery was estimated and personal dose equivalents, Hp(10) and Hp(0.07), were measured during SNNS. Materials and methods: Seventeen breast cancer patients were enrolled. One day before SNNS, 99m Tc-Sn colloid was injected around the tumor and radiation exposure rates were measured using survey meters. Personal dose equivalents for the surgical workers were measured. Hp(10) and Hp(0.07) for the body and Hp(0.07) for the hands were recorded using semiconductor detectors and ring-type glass dosimeters. Results: The maximum Epoten was 29 μSv per 74 MBq injection. The maximum Hp(10) for the primary and assisting surgeons, nurse, and anesthetist was 3.7, 1.4, 0.3 and 0.6 μSv per SNNS, respectively. The maximum Hp(0.07) for the hands was 100 μSv. Maximum radiocontamination 20 times higher than background (0.05 μSv/h) was detected in bloody gauze. Conclusion: The workers' radiation dose exposure from SNNS was not high, although radiation management such as a temporary cooling off period may be required.