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Radioactive Seed Localization

Radioactive Seed Localization. Margarita Zuley, MD Associate Professor of Radiology University of Pittsburgh Medical Director Breast Imaging Magee Womens Hosp of UPMC. Thank you to Mike Sheetz University of Pittsburgh RSO . Background.

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Radioactive Seed Localization

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  1. Radioactive Seed Localization Margarita Zuley, MD Associate Professor of Radiology University of Pittsburgh Medical Director Breast Imaging Magee Womens Hosp of UPMC

  2. Thank you to Mike Sheetz University of Pittsburgh RSO

  3. Background • Significantly decayed I-125 seeds used for brachytherapy • Assayed activity approx 200 microcuries • Half-life of I-125 is 60 days • Can be placed into the breast like a biopsy clip easily with ultrasound or mammography guidance

  4. Background Work pioneered by Mayo Clinic Almost no contraindications to placement Used to localize lesion in breast for surgical excision Emit a different frequency energy than Tc-99m and so can be detected in the OR even with a sentinel node injection of Tc-99m

  5. Benefits • Studies indicate reduced incidence of positive margins compared to wire localization • Allows for improved surgical approach and removal of lesion • Reduces scheduling conflicts between surgeon’s and radiologist’s offices

  6. Regulatory Oversight • PA Department of Environmental Protection Bureau of Radiation Protection regulates use of radioactive material (RAM) in medicine • Apply to DEP for a RAM license if not pre-existing • RSL is an off-label use of a device • Radiation Safety Office or Officer must be involved from the very beginning

  7. Coordinated Program • Radiation Safety Office • Oversees protocol of training/ implementation • Develops policies for handling • Develops policies for storage and transfer • Develops policies for lost/ damaged seeds

  8. Training Requirements • Didactic training provided by RSO on RSL policies and procedures • Supervised work experience • Radiologist – minimum of 2 cases • Surgeon – minimum of 1 case • Pathologist or PA – minimum of 1 case • Specific medical staff privilege for radiologists and surgeons • Annual refresher training

  9. Radiation Safety Issues Personnel Exposure Inventory Source Leakage Surveys Security

  10. Radiation Exposure to the Population of the United States Early 1980’s2006 Effective Dose per Individual 360 620 In the U.S. Population (mrem) Early 1980’s2006 Effective Dose per Individual 360 620 In the U.S. Population (mrem) 1980’s2006 Effective Dose per Individual 360 620 in the U.S. Population (mrem) NCRP Report No. 160

  11. Dose Rate from 200 uCi I-125 seed Medical Imaging Doses Radiation Exposure Potential Annual Occupational Exposure Limits: Whole body – 5000 mrem Extremity – 50,000 mrem Mettler et al. Radiology 2008

  12. Radiation Safety • ALARA Philosophy (As Low As Reasonably Achievable) • Radiation Protection Measures • Time (plan in advance) • Distance (reverse action tweezers) • Shielding (lead containers for transport and storage) • Radiation dosimetry not required

  13. Radiation Safety Issues Inventory - Constant tracking of seed with computerized inventory system Source Leakage – Radioactivity is sealed inside titanium wall which is “soft” and can be easily cut Surveys – Radiation monitoring is performed with gamma probe or NaI meter to locate seed Security – Seeds must be kept in secured area or be under supervision of authorized individual

  14. Coordinated Program • Radiologist • Surgeon • Pathologist • Administrators • All clinicians must have initial training by someone skilled in the procedure. • Can have a super user in each specialty that trains peers • Form a team with the RSO to implement the program

  15. Consider seed movement • Order and receipt in Nuclear Medicine • Storage in Breast Imaging • Placed under US or mammo guidance • Surgical removal in OR • Specimen radiography in breast imaging • Seed removed from specimen in pathology • Used seeds stored in breast imaging • RSO picks up spent seeds for disposal

  16. I-125 Seed Ordering • Order seeds separately and place them into needles in radiology • Have to consider sterility • Less expensive • Order prepackaged seeds that are already sterile

  17. I-125 Seed Implant Prescription for implant completed and signed by radiologist prior to implant Seed implanted under radiographic or ultrasonic guidance by authorized radiologist Confirmatory mammogram taken to verify seed placement Survey of room performed to assure seed not dropped or cut

  18. I-125 Seed Implant Seed is positioned at the center of the lesion Seed cannot be repositioned Rare incidence of seed migration Surgery to remove seed must be scheduled within 1 half life (60 days)

  19. Patient Instruction Patient provided written information on radioactive seed localization option from surgeon No special instruction given to patient with respect to radiation exposure to others Emphasis that patient must return for scheduled surgery to remove radioactive seed

  20. Surgical Removal Of I-125 Seed • Identification of surgical patient containing I-125 seed • Handheld gamma probe is scanned across breast • Probe set at 27 keV to detect gamma radiation from I-125

  21. Gamma Probe Spectrum for I-125 and Tc-99m

  22. Surgical Removal Of I-125 Seed Point of greatest activity locates seed and lesion Surgical incision is made over “hot spot” Gamma probe is used to guide the excision of the lesion

  23. Steps After Resection of Lesion Survey specimen with gamma probe to confirm presence of radioactive seed Survey surgical site to confirm absence of radioactive seed Place specimen in plastic container, label with radiation sticker, transport to Breast Care Center for radiograph

  24. Surgical Concerns • Cutting of radioactive seed • No dissection with scissors • Suctioning of seed from surgical site • Misidentification of I-125 seed radiation from Tc-99m sentinel node activity

  25. Pathology Specimen transported from BCC back to OR/Pathology lab Number of seeds in specimen noted on container lid Locate seed(s) in specimen using radiograph and/or gamma probe

  26. Pathology Remove seed using scalpel (no scissor dissection) Place seed into plastic vial with patient RX number using reverse action tweezers, secure cap, and put vial in lead pig

  27. Pathology Scan breast tissue specimen with gamma probe before releasing for sectioning Complete seed removal log sheet Breast Care Center techs will pick-up container with radioactive seed(s) at end of day

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