Guidelines for the safe use of radioactive materials during localization and resection of the sentinel lymph node

Background: Several reports have demonstrated accurate prediction of nodal metastasis with radiolocalization and selective resection of the radiolocalized sentinel lymph node (SLN) in patients with breast cancer and melanoma. As reliance on this technique grows, its use by those without experience in radiation safety will increase. Methods: Tissue obtained during radioguided SLN biopsies was examined for residual radioactivity. Specimens with a specific activity greater than the radiologic control level (RCL) of 0.002 mu Ci/g were considered radioactive. Radiation exposure to the surgical team was measured. Results: A total of 24 primary tissue specimens and 318 lymph nodes were obtained during 57 operations (37 for breast cancer, 20 for melanoma). All 24 (100%) of the specimens injected with radiopharmaceutical and 89 of 98 (91%) of the localized nodes were radioactive after surgery. Activity fell below the RCL 71 +/- 3.6 hours in primary tissue specimens, 46 +/- 1.7 hours in nodes from melanoma patients, and 33 +/- 3.5 hours in nodes from breast cancer patients (P =.037). The hands of the surgical team (n = 22 cases) were exposed to 9.4 +/- 3.6 mrem/case. Conclusion: Although low levels of radiation exposure are associated with radiolocalization and resection of the SLN, the presented guidelines ensure conformity to existing regulations and allow timely pathologic analysis.