Radiation safety with breast sentinel node biopsy.

BACKGROUND: Sentinel lymph node biopsy with Technetium 99m sulfur colloid (Tc99m) is an evolving technique that offers the potential for improved staging of breast cancer with decreased morbidity. However, the use of radioactive materials in the operating room generates significant concern about radiation exposure. The purpose of this study was to evaluate radiation exposure to operating room personnel, pathologist, and equipment from specimens during breast sentinel lymph node biopsy.
METHODS: Twenty patients were injected with 0.7 to 1.1 mCi of Tc99m sulfur colloid 1.5 to 3 hours before sentinel lymph node biopsy. A calibrated Geiger counter was used to measure dose rates from the breast injection site before skin incision (n = 20), lumpectomy specimens (n = 8), and sentinel nodes (n = 20) at distances of 3, 30, and 300 cm. This represented exposure to the surgeon's hands, surgeon's torso, and scrub nurse, respectively. Exposure to the pathologist's hands and torso was represented as dose-rate measurements from lumpectomy and nodal specimens. The operative instruments, trash receptacles, suction canisters, pathology slides, and cryostat machines were measured at 3 cm at the conclusion of each procedure. Specimens or equipment emitting radiation doses equal to background levels (0.04 mRem/h) were exempt from special handling and disposal.
RESULTS: The highest exposure rate was to the surgeon's hands from the breast injection site before skin incision (34.25 mRem/h). Exposure to the surgeon's torso measured 1.33 mRem/h, and exposure to the scrub nurse's torso measured 0.15 mRem/h from the injection site. Exposure to the pathologist's hands was 18.62 and 0.06 mRem/h from the lumpectomy specimen and sentinel node, respectively. Exposure to the pathologist's torso measured 0.34 and 0.04 mRem/h from the lumpectomy specimen and sentinel node, respectively. One hundred percent of lumpectomy specimens measured above the exempt level. Thirty-two of 46 (70%) sentinel lymph nodes emitted radiation equal to the exempt background level. Seventeen of 20 trash receptacles (85%) and 4 of 12 (33%) suction canisters measured equal to background levels. All operative instruments, pathology slides, and cryostat machines were equal to background levels.
CONCLUSIONS: Radiation exposure to operating room personnel, pathologists, and operative equipment during a breast sentinel node biopsy using Tc99m is minimal. A primary surgeon can perform 2,190 hours, a scrub nurse 33,333 hours, and a pathologist 14,705 hours of procedural work before surpassing Occupational Safety and Health Administration limits. Operative instruments, pathology slides, and cryostat machines do not require special handling. All lumpectomy specimens should be stored for decontamination until the dose rate equals background levels. Intraoperative dose-rate monitoring allows selective decontamination of nodal specimens, trash receptacles, and suction canisters, which decreases disposal time and cost.