Radioactive Seed Localization With 125I For Nonpalpable Lesions Prior to Breast Lumpectomy and/or Excisional Biopsy

Abstract

The use of radioactive seed localization (RSL) as an alternative to wire localizations (WL) for nonpalpable breast lesions is rapidly gaining acceptance because of its advantages for both the patient and the surgical staff. This paper examines the initial experience with over 1,200 patients seen at a comprehensive cancer center. Radiation safety procedures for radiology, surgery, and pathology were implemented, and radioactive material inventory control was maintained using an intranet-based program. Surgical probes allowed for discrimination between 125I seed photon energies from 99mTc administered for sentinel node testing. A total of 1,127 patients (median age of 57.2 y) underwent RSL procedures with 1,223 seeds implanted. Implanted seed depth ranged from 10.3-107.8 mm. The median length of time from RSL implant to surgical excision was 2 d. The median 125I activity at time of implant was 3.1 MBq (1.9 to 4.6). The median dose rate from patients with a single seed was 9.5 µSv h-1 and 0.5 µSv h-1 at contact and 1 m, respectively. The maximum contact dose rate was 187 µSv h-1 from a superficially placed seed. RSL performed greater than 1 d before surgery is a viable alternative to WL, allowing flexibility in scheduling, minimizing day of surgery procedures, and improving workflow in breast imaging and surgery. RSL has been shown to be a safe and effective procedure for preoperative localization under mammographic and ultrasound guidance, which can be managed with the use of customized radiation protection controls.

Selective Surgical Localization of Axillary Lymph Nodes Containing Metastases in Patients With Breast Cancer

“…Lymphoscintigraphy cameras capture 120-150 keV, thus not detecting the I 125 emission. [12, 13] SLNs were able to be identified in all patients where SLN dissection was attempted. The mean number of SLNs retrieved was 2.4 (range 1-6).…”

“…The seeds are made of titanium and contain I 125 which emits 35 keV of gamma radiation and has a half-life of 60 days. [12, 13] Our institution has limited the number of seeds inserted in a patient to 4 to limit excess radiation exposure – this allows for placement of the seed in axillary nodes even when multiple seeds are needed to localize breast lesions. Standard handheld gamma probes used for SLN detection can be used to localize both the I 125 seed as well as radioisotope-containing SLNs by changing the energy mode.…”

“…Surgeons comfortable using gamma probes to identify radioisotope-containing SLNs should be able to accurately identify the seed-containing node intra-operatively, although precautions must be in place because of the radioactive material similar to those used when I 125 seeds are used to guide segmental mastectomy. [12, 13] Removal of the clipped node is confirmed by intra-operative x-ray which requires a participating pathologist and radiologist. Similar to intra-operative assessment for breast localization, handling and disposing of the I 125 seed must also be performed in concordance with radioactive safety guidelines.…”

Initial Community Hospital Performance of Radioactive Seed Localization for Breast Cancer Patients

“…Since the activity of the I-125 source is so low, the patient is free to conduct all of her normal activities (Dauer et al, 2013). She does not need to restrict her contact with other people.…”

The use of radioactive iodine-125 seed localization in patients with non-palpable breast cancer

“…A gamma probe is used to locate the tumour with the radioactive seed during surgery. 16,17 ROLL and RSL have been compared to WGL in several studies and were both strongly favoured over WGL. 18e25 A lower rate of positive margins was shown in most studies.…”