More About Biodosimetry
What is the difference between radiation biodosimetry and radiation bioassay?
- Radiation biodosimetry: basic description
- Bioassays (more specifically radio-bioassays) test whether and how much internal radiation contamination has occurred.
- Radiation bioassays
- Measure radioactivity directly in biological specimens (e.g., blood, urine, feces, sweat, or other materials)
- Results can be used to calculate radiation dose to the whole body or to a specific organ.
- Measure the effectiveness of treatments over time for mitigating internal contamination
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Why is it useful to estimate the dose received from radiation exposure in a radiation event?
- Significant whole- or partial-body radiation can lead to the Acute Radiation Syndrome (ARS) and delayed radiation effects
- ARS severity increases with
- Radiation dose (see below)
- Dose rate: the higher the dose rate, the more severe the damage
- Certain host factors
- Extremes of age (e.g., very old, very young)
- Certain chronic diseases including immunocompromising illnesses
- Combined injury: radiation exposure plus physical trauma and/or burns
- The greater the whole- or partial-body radiation dose
- The earlier the onset of signs and symptoms of ARS
- The more severe the clinical manifestations
- The worse the clinical outcome/prognosis
- Knowing/estimating the whole- or partial-body radiation dose facilitates
- Selection of appropriate prophylactic and therapeutic measures
- Estimation of a person's prognosis, especially useful for resource allocation in mass casualty situations
- Transfer of appropriate patients to facilities with the expertise to manage severe ARS
- In some cases clinical effects of ARS can be anticipated and potentially mitigated.
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What is physical dosimetry?
- 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
- Many different kinds of devices are used
- Computerized 2D or 3D models of radiation levels
- Can be generated from data in actual radiation events or theoretical models of events, including in specific venues
- These 2-D or 3-D models of radiation levels can be overlaid on maps and can track changes over time.
- After a radiation event, theoretical models can provide initial estimates of dose at locations of interest.
- As actual radiation survey data become available after an event, the accuracy of the radiation level maps improves.
- Mapping information can help provide
- Knowing a victim's location in relation to the epicenter of a radiation event can be used to estimate dose. Key considerations include
- Time: How long did the patient spend in the radiation field? The longer an individual spends in a radiation field, the greater the overall whole-body radiation dose.
- Distance: How far and where was the patient located from the epicenter of the radiation event? Radiation plume and footprint maps of the event will show the radiation levels within the impacted geographical area. Sequential maps can show how radiation levels change over time at various distances from the epicenter.
- Shielding: Was the patient protected by any significant shielding, (e.g building walls of wood vs. concrete) that could have attenuated whole body radiation dose?
- Time, Distance, Shielding Illustration
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What clinical clues help provide estimates of radiation dose? 3
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How do you use biodosimetry information generated by 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? 4
- Use the highest whole body dose estimate to plan treatment initially.
- Modify the dose estimate and treatment plan as additional clinical and laboratory data are obtained over time.
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References |
- Alexander GA, et al., BiodosEPR-2006 Meeting: Acute dosimetry consensus committee recommendations on biodosimetry applications in events involving uses of radiation by terrorists and radiation accidents. (PDF - 518 KB) Radiat Meas. 2007 July;42(6-7):972-96.
- Radiation Dosimetry Monograph: "Applications of Dosimetry in Radiation Epidemiology" (Radiation Research, July 2006, Volume 166, Number 1. Special Supplement) (HHS/National Cancer Institute/Division of Cancer Epidemiology and Genetics)
- Fliedner TM, Friesecke I, Beyrer K. Medical Management of Radiation Accidents: Manual on the Acute Radiation Syndrome. (METREPOL) (PDF - 970 KB) (originally published by Oxford: British Institute of Radiology; 2001) Compendium to the main METREPOL document (PDF - 580 KB)
- Lloyd DC, Edwards AA, Moquet JE, Guerrero-Carbajal YC. The role of cytogenetics in early triage of radiation casualties. Appl Radiat Isot 2000 May;52(5):1107-12. [PubMed Citation]
- Introduction to radiation physics and dosimetry (PDF -4.67 MB) (Steven L. Simon, Radiation Epidemiology Course, May 2007, HHS/National Cancer Institute/Division of Cancer Epidemiology and Genetics)
- Waselenko JK, MacVittie TJ, Blakely WF, Pesik N, Wiley AL, Dickerson WE, Tsu H, Confer DL, Coleman CN, Seed T, Lowry P, Armitage JO, Dainiak N; Strategic National Stockpile Radiation Working Group. Medical management of the acute radiation syndrome: recommendations of the Strategic National Stockpile Radiation Working Group. Ann Intern Med. 2004 Jun 15;140(12):1037-51. [PubMed Citation]
- Acute Radiation Syndrome: A Fact Sheet for Physicians (HHS/CDC)
- See Dose Estimators (Biodosimetry Tools) for more references on dicentrics and other biodosimetry assays
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