More About Biodosimetry
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?
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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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Three Tables Comparing Biodosimetry Assays
- Cytogenetic aberration assays used for dose assessment (PDF - 64 KB),
adapted from Cytogenetic Dosimetry: Applications in Preparedness for and Response to Radiation Emergencies, Table 1, page 3, (IAEA, PAHO, WHO, September 2011)
- Summary of advantages and disadvantages of existing and developing techniques for assessment of radiation exposure levels,
adapted from High dose radiation effects and tissue injury, Report of the Independent Advisory Group on Ionising Radiation, Table 4.4, page 41 (Health Protections Agency, UK, March 2009) (PDF - 865 KB)
- Comparison of retrospective dosimetry assays (PDF - 97 KB),
adpated from Ainsbury EA, Bakhanova E, Barquinero JF, et al., Review of retrospective dosimetry techniques for external ionising radiation exposure. Table 1, Radiat Prot Dosimetry. 2011;147(4):573-92. Epub 2010 Dec 23. [PubMed Citation]
Notes:
- See Biodosimetry Reference List for additional biodosimetry techniques currently under development.
- Many of these newer biodosimetry techniques could be considered when used by experts as supplemental data for clinical evaluations...
- If performed by experienced, reference laboratories using procedures that have been precisely calibrated for specific conditions
- But most are probably not FDA-certified for clinical use in evaluating radiation exposure
- But most are currently not feasible in large mass casualty events needing high throughput
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