Radioactive seed localization (RSL) is a new technique for surgical identification of nonpalpable breast lesions. We describe the preparation of the needle with I-125 seeds for ultrasound-guided deposition in breast lesions. In a feasibility study we investigated the minimum activity amount needed for reliable gamma probe identification of the seeds and the levels of exposure to the staff.

METHODS: 11 patients received a seed, which was manually placed in an 18 gauge needle with bone wax occluding the tip, and the radiologist introduced it into the breast tissue guided by ultrasound. The seed was located during the operation with a handheld gamma probe. The activity amount required was studied in a water bath. Radiation exposure to the fingertips of pathologists was measured by a thermoluminescent dosemeter.

RESULTS: All seeds were successfully prepared, positioned in the breast lesion, and easily identified. The surgeon removed the seeds together with the breast lesions, and they were identified by the pathologist. There were no unexpected adverse drug reactions. Water bath studies suggest that 1-3 MBq I-125 was sufficient for precise identification, regardless of the presence of conventional Tc-99m activity from sentinel node injection. The total finger dose exposure to the pathologists for the 8 procedures was below the detection limit of 0.1 mSv.

CONCLUSION: I-125 seeds for ultrasound-guided deployment and surgical identification of breast lesions were successfully prepared and identified for this promising new radioguided surgical technique. The radiation exposure to staff involved is considerably below the permissible limits and almost negligible.