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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

Radioactive Seed Localization

Margarita Zuley, MD

Associate Professor of Radiology

University of Pittsburgh

Medical Director Breast Imaging

Magee Womens Hosp of UPMC

slide2

Thank you to Mike Sheetz

University of Pittsburgh RSO

background
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
background4
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

benefits
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
regulatory oversight
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
coordinated program
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
training requirements
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
radiation safety issues
Radiation Safety Issues

Personnel Exposure

Inventory

Source Leakage

Surveys

Security

radiation exposure to the population of the united states
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

radiation exposure potential
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

radiation safety
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
radiation safety issues13
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

coordinated program14
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
consider seed movement
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
i 125 seed ordering
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
i 125 seed implant
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

i 125 seed implant18
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)

patient instruction
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

surgical removal of i 125 seed
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
surgical removal of i 125 seed22
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

steps after resection of lesion
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

surgical concerns
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
pathology
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

pathology26
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

pathology27
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