Radioactive Cases in Histology or Autopsy

• Purpose
• Specimen Requirements
• Materials Required
• Procedures
• Waste Disposal

Purpose:

Radioisotopes such as Yttrium-90 and Indium-111 are used for diagnostic studies and cancer treatments. These have short half-lives; 64 hours in the case of Y-90. In very rare instances, the Laboratory of Pathology may receive a tissue sample that is still radioactive after treatment with these or other radiation therapies. In order to preserve the histology and immunoreactivity of the tissue, the sample must be grossed and processed to paraffin while still radioactive or “hot”. To do this safely and in compliance with NIH policy, the procedures for these activities are modified as indicated below. The following must be done in close collaboration with the Radiation Safety Branch (301-496-5774) and Radioactive Waste Management (301-496-4451).

Technical staff or residents must notify the attending pathologist and Health Physicist if there is a case involving potentially radioactive specimens. 

Specimen Requirements:

All routine labeling requirements apply. The tissue specimen must be received fresh or in 10% neutral buffered formalin and labeled as such. In addition, the specimen container(s) must be labeled with: “Caution Radioactive Material (CRM)” labels, the type of radioisotope, and the date it was administered to the patient.

Materials Required:

• CRM labels
• Plexiglas shielding box
• Designated work area for radioactive materials in a locked room (radiation work area)
• Nitrile or similar gloves, plastic apron
• 10% neutral buffered formalin (Scientific Supplies and Solutions #EKI-4499-20L) or equivalent
• Plastic specimen containers
• Back-up tissue processor, not used for routine work.
• All solutions for the tissue processor.  
• Cassettes and cassette cage to place in tissue processor

Procedures:

1. Upon receipt, refrigerate the sample in a locked area; do not leave unattended.
2. Contact the Director of Clinical Operations or the attending pathologist immediately. He/she will contact the Radiation Safety Branch for a radiation physicist to come and test the sample for radioactivity.
3. If the sample is not fixed, leave it that way until the radiation physicist has tested it. The testing, therefore, must occur as soon as possible so that formalin can be added.
4. If the radiation physicist does not detect radioactivity, the tissue sample can be processed as any other formalin fixed sample. Place in formalin, if not already, and give to Histology for routine processing.
5. If the radiation physicist does detect radioactivity, move to a designated working area for radioactivity until subsequent steps are coordinated. Place tissue in formalin if it is not already in formalin.
6. Give the CRIS order to Histology to accession the case and make labeled cassettes as usual. Place a flag in SoftPath to indicate that processing will be delayed due to radioactivity.
7. At the radiation work area, gross in the tissue and place in cassettes as usual. Do this as soon as possible to optimize fixation.
8. Depending upon the amount of radioactivity found, two (2) courses of action are possible:
   1. The tissue can be held in cassettes at the radiation work area until no radioactivity is detected or
   2. The cassettes can be processed immediately to paraffin.
   3. These two (2) options need to be discussed with the pathologist and the radiation physicist. If the tissue mass and isotope do not suggest that radioactivity will be gone in several days, the tissue should be processed immediately to avoid artifact from extended time in fixative (go to step #10).
9. If the option to hold the cassettes is chosen, keep them at the radiation work area until the radiation physicist retests them. If no radiation is found, submit the cassettes for routine processing as usual. If they are radioactive, process them as described below.
10. Transport radioactive samples to the back-up tissue processor in a Plexiglas container that is labeled with CRM labels.
11. Place cassettes in the processor with a specimen basket or similar holding device that will not be needed again until all traces of radiation are gone.
12. Process using the same processing schedule that would be used if the tissue were not radioactive. Put CRM labels on the tissue processor. Put a note on the processor to alert staff not to disturb it.
13. After processing is complete, move cassettes to a clean plastic container. Put this in a Plexiglass container and transport to the radiation work area. The infiltrated tissue is stable at room temperature without embedding.
14. Perform a clean cycle on the processor as usual. Leave the reagents and specimen basket as they are until cleared by the radiation physicist.
15. Call the radiation physicist to retest the tissue cassettes and tissue processor at the designated date.
16. Once cleared, the cassettes can be embedded, sectioned and stained as usual.
17. The processor can be used again. The chemicals can be disposed of in the usual formalin and flammable waste streams. Remove the CRM labels.

Waste Disposal:

Gloves and any non-liquid waste generated when handling the radioactive samples must be discarded in a MPW box that is labeled as radioactive waste. Liquid wastes must be captured in waste bottles labeled with the chemical name (e.g., Formalin), the volume, and the name of the contaminating radioisotope. Consult the NIH waste disposal flip charts. Call Radioactive Waste for pickup (301-496-4451).

The chemicals in the processor can be disposed of in the usual formalin and flammable waste streams once they are cleared by Radiation Safety. If they must be disposed of before then, capture in waste bottles labeled with the chemical name, volume, and the name of the radioisotope. The alcohols and xylene can be mixed together. The formalin and paraffin must be kept separate.

Paraffin trimmings from tissue that has been cleared by the radiation physicist can be discarded in regular trash bins. Microtome blades must be discarded in a sharps container as usual.

Additional information regarding handling of radioactive specimens is as follows:

• There are two principles to be followed when dealing with radioactivity in medical specimens. The first is to determine if exposure poses a medical risk and the second is to minimize exposure to radiation regardless of risk. Adequate communication and education of personnel is extremely helpful to avoid problems and misconceptions when dealing with sentinel node specimens.

• Radioactive specimens emit radiation that may reach the body and deposit energy in cells. The dose that one would receive working near a radioactive source is dependent on three (3) factors: 1) the level of radioactivity emanating from the specimen; 2) the time spent handling the specimen; and 3) the distance from the source. The radiation dose is directly proportional to the level of radioactivity and the amount of time spent near the source. However, the dose falls off rapidly with distance following an inverse square relationship; for example, doubling the distance reduces the exposure rate by a factor of four. The amount of energy deposited is measured in units of millirem. For example, if the dose at the surface of a specimen container is 2.5 millirem/hour, it is necessary to handle the specimen at that short distance for 1 hour to receive a dose to the hands of 2.5 millirem. Areas of the body that are further away from the hands (i.e., the rest of the body) will receive substantially less radiation, in this case less than 0.2 or 0.3 millirem. Note that this assumes 1 hour of handling; for a 15-minute procedure, values would be four times less, and the result would be doses that are extremely small. To provide a reference for this unit, residents of Vermont receive about 10 millirem per month due to background radiation. A chest X-ray results in a skin dose of about 30 millirem.

• Sentinel node specimens and breast excisions that contain radioactivity may be sent directly to pathology. The handling, administration, and disposal of radioactive material should be performed in accordance with institutional policy. All radioactive specimens should be labeled with a sticker indicating the presence of radioactive material. The amount of radioactivity that they contain will vary depending on the procedure. No significant hazard associated with the handling of these specimens has been documented. Data collected at the University of Vermont and Fletcher Allen Health Care indicate the magnitude of radiation exposure is such that no protection is required for the patient or personnel caring for the patient. Data published from Baylor University Medical Center indicate that a pathologist would need to have over 14,000 hours of direct contact with sentinel node specimens before exceeding OSHA Guidelines. Although there is no known danger to a fetus with the levels of radioactivity in sentinel node specimens, it is a general policy to avoid any exposure of an early fetus to radiation. The College of American Pathologists has published recommendations for handling specimens obtained in sentinel node procedures.

• The amount of radioactivity present is constantly decreasing due to radioactive decay. Currently, the material being used has a short half-life and decays to close to background levels in one day. To minimize exposure to radiation and prevent any contamination of the surgical pathology suite with radioactivity, the following precautions are suggested. If clinically appropriate, store the specimen for 24 hours; care should be taken to assure optimal fixation. During this time, activity will decay to almost background levels. Handle the specimen for the shortest time reasonable in the first 24 hours. Wash all areas that might be contaminated.