What You Need to Know About Biodosimetry:
The Basics


What is the difference between radiation biodosimetry and radiation bioassay?


  • Radiation biodosimetry: definition
  • Radiation bioassays measure
    • Whether internal contamination has occurred
    • What isotopes are detected
    • How much internal contamination has occurred
  • Bioassays measure radioactivity directly in biological specimens
    • Examples: blood, urine, feces, sweat
  • Bioassay results can be used to
    • Estimate radiation dose (to the whole body or specific organs) expected to be accumulated in the future over a specified period of time
    • Measure the ongoing effectiveness of treatments for internal contamination
  • Examples of units of measure for radiation exposure from internal contamination
    • After internal contamination: various units are used including, e.g. Committed Effective Dose Equivalent (CEDE)
    • After both external exposure and internal contamination: various units are used including Total Effective Dose Equivalent ( TEDE)

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Why is biodosimetry needed?


  • Since most victims of large mass casualty radiation emergencies would not be wearing personal dosimeters, other methods must be used to estimate the dose they received
  • Biodosimetry helps to
    • Predict the time course and severity of the phases of the Acute Radiation Syndrome
    • Facilitate short term triage, including where the patient should be treated
    • Suggest countermeasure that will be needed to treat ARS, especially acutely
    • Assess the risk of long term consequences from radiation exposure.

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What is physical dosimetry?


  • Actual measurements of radiation exposure made by detection equipment including
    • Personal dosimeters
      • Worn on outside of clothing by workers in an actual or potential radiation environment to track exposure
      • Measure the radiation dose received by the device
      • Knowing the location of the device on the wearer's person helps interpret the significance of the dosimetry reading for the wearer
      • Many different kinds of devices are available
    • Survey meters
      • Measure radiation levels in the environment
      • Can be used to estimate dose that may have been received by workers or victims in the area assessed by the meter
      • Different kinds of devices are used for specific tasks.

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What is dose reconstruction?



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What clinical clues help provide estimates of radiation dose?


  • Evaluate subsyndrome severity scores for the 4 ARS subsyndromes
    • A higher severity score for any of the subsyndromes is generally correlated with higher absorbed dose
    • Subsyndromes
      • hematopoietic subsyndrome
      • cutaneous subsyndrome
      • gastrointestinal subsyndrome
      • neurovascular subsyndrome (a.k.a. Cerebrovascular)
  • A targeted physical exam is also useful.

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How do you use the REMM Dose Estimator for Exposure?


  • The REMM Dose Estimator for Exposure provides information that can help responders assess, triage, and manage victims.
  • Providers should
    • Collect and consider all the physical, clinical and laboratory information and observe how data change over time.
    • Correlate information from victim's history and physical, including signs and symptoms, with specific radiation effects expected at various doses.
    • Use physical dosimetry information if and when it is available.
      • Was the victim wearing a personal radiation dosimeter? This would be unlikely in a terrorist event but likely for an occupational radiation worker.
      • Do incident managers have information about radiation dose in the geographic area where the victim was at the time of the incident?
    • Register the victim in the incident data base using the best biodosimetry and clinical information available.

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What should you do when there are conflicting dose estimates?


  • Initially, use the highest whole body dose estimate to plan treatment.
  • Modify the treatment plan as additional clinical and laboratory data are obtained over time.

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Use of biodosimetry in long term surveillance studies after radiation exposure

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References


See Biodosimetry Reference List