Dose Reconstruction



Estimate Exposure

Estimate exposure by:

  • Location of patient in relation to epicenter and radioactive fallout maps
  • Duration of time patient was exposed to radiation
  • Shielding between patient and radiation
  • Type of radiation the patient was exposed to


What is Dose Reconstruction?

  • Retrospective evaluation of radiation dose(s) received by identifiable or representative individuals or populations from a particular exposure "situation of concern".
  • Several different types of dose reconstructions are recognized:
    • Dose reconstruction for radiation emergencies — Initial estimates often are required on short notice because the incident is unplanned, occurs without warning, and may require immediate triage and treatment of many victims.
      • This type of dose reconstruction is the primary focus of REMM.
      • Various government agencies will initially sample areas of concern in the environment and use computer programs to create "dose" or "exposure" maps. These maps will be refined over time as more data are obtained, and radiation levels change. (See environmental software programs.)
      • These emergency environmental radiation maps are likely to help provide initial and continuing estimates of dose for individuals who were/are located there and help incident managers plan the response.
      • Biodosimetry tools and bioassays may need to supplement the increasingly detailed estimates of dose/exposure to individuals whose location is described on these regional maps.
      • Depending on the type of emergency, exposure or contamination pathways may be more important.
    • Medical dose reconstruction is a retrospective dose estimation of radiation exposure that was received during a diagnosis of or treatment for a medical condition or disease
    • Occupational dose reconstruction is concerned with estimating past radiation exposures received by individuals as a result or condition of their employment. Workers may have specialized in businesses related to radionuclides or radiation-generating devices (e.g., nuclear plant workers, radiologists) or simply been exposed to radiation fields by their presence at certain events (e.g., atomic veterans). Frequently, individual monitoring data are available.
    • Environmental dose reconstruction is typically a dose reconstruction that is undertaken for members of the public who may have been exposed due to the operation of a specific facility (e.g., the Hanford Site) or to a widespread practice (e.g., atmospheric testing of nuclear weapons) in which radiation or radioactive materials have been released into the environment.

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Uses of Dose Reconstruction

(Adapted from Radiation Dose Reconstruction: Principles and Practices, NCRP Report No. 163, page 21, Bethesda, MD, 2009)

  • Support management of radiation emergencies, such as providing input to decisions on protection of emergency workers and members of the public or medical treatment of exposed/contaminated individuals
  • Provide exposed individuals or populations with information on doses they received
  • Determine the probability that an individual's disease might have been induced by exposure to radiation
  • Investiage dose-response relationships in epidemiologic studies
  • Determine whether individuals whose disease might have been induced by radiation qualify for compensation

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Dose Reconstruction Process

Adapted from NCRP Report 163

  • Thorough dose reconstruction is a process that begins with a defined purpose and objectives and is carried out in a logical and orderly manner.
  • In mass casualty settings, patient management may need to begin with whatever dose/exposure information was available at the time of the urgent first encounter. This initial information may be incomplete, but it can be refined over time.
  • 5 essential steps of dose reconstruction
    1. Definition of exposure scenarios incorporating 2 kinds of information
      • Description of individuals or populations of concern
        • Personal characteristics
        • Activities at locations where radiation exposure could have occurred
        • Times spent at those locations
        • Shielding
      • Description of sources of radiation exposure
    2. Description exposure pathways including 4 required parameters
      • Source of radiation
      • Mechanism for transport from the source to the air, surface water, groundwater and/or soil
      • Point where people come in contact with contaminated air, surface water, groundwater or soil, and
      • Route of entry into the body include
        • Direct exposure to penetrating radiation
        • Eating or drinking contaminated materials,
        • Breathing contaminated air
        • Absorbing contaminants through the skin or an open wound
        • Injection or implantation
    3. Development and implementation of methods of estimating dose
    4. Evaluation of uncertainties in estimates of dose
    5. Presentation and interpretation of analyses and results
  • Two foundational elements of the entire dose-reconstruction process that are integral to performing each step
    • Data and other information
    • Quality assurance and quality control

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Example of how to elicit basic information for dose reconstruction of exposure & contamination

  • Where were you when the incident happened? (Match to the maps of fallout when they become available.)
    • If you were indoors: building name, street address, floor, room, location in room (Shielding information may become available which will help refine dose estimate.)
    • If you were outdoors: street and cross street or other markers of location (Assesses possible inhalation of radioactive material and exposure)
    • If you were in your car: Where was the car? Were the windows open?
  • What time did you first notice the incident?
    • What did you notice?
  • If you were inside a building
    • Were the windows open where you were? (For possible inhalation of radioactive material)
    • Can you or someone else provide detailed information about building/room/furniture construction and location in relation to where you were? (Helps estimate the possible effects of shielding)
    • Can you or someone else determine if the building air handling system was working at the time of event? (Helps determine whether there was intake of radioactive material from the air as the fallout cloud passed over the area)
  • If you moved from where you were at the time of the incident, can you tell me exactly where you went after that and about what time you got to various landmarks along the way?
  • Did you have any nausea or vomiting?
    • If yes, tell me what time you noticed nausea/vomiting for the first time and how severe it has been.
    • Time to vomiting is one tool to help estimate dose from exposure, even though
      • Vomiting is not always related to radiation exposure and can have many other causes.
      • All radiation exposure is not uniform across the body.

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References


NCRP References: project reports relevant to dose reconstruction

  1. Radiation Dose Reconstruction: Principles and Practices, NCRP Report No. 163, page 21, Bethesda, MD, 2009.
  2. Uncertainties in Internal Radiation Dose Assessment, NCRP Report No. 164, Bethesda, MD, 2009.
  3. Uncertainties in the Measurement and Dosimetry of External Radiation, NCRP Report No. 158, Bethesda, MD, 2007.

Assessing Doses: Federal Radiological Monitoring and Assessment (FRMAC)

  1. Technical methods for performing radiological assessments and basis for FRMAC software.
  2. These methods are documented in the FRMAC Assessment Manuals for use in the event of the intentional or accidental release of radioactive material to guide and govern the response of the Federal, State, Local, and Tribal governments.

REMM has related information about

  1. Biodosimetry
  2. Dose Estimator for Exposure
  3. Software Tools for Radiation Incident Response

Other references

  1. 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)
  2. Bouville A, Toohey RE, Boice JD Jr, Beck HL, Dauer LT, Eckerman KF, Hagemeyer D, Leggett RW, Mumma MT, Napier B, Pryor KH, Rosenstein M, Schauer DA, Sherbini S, Stram DO, Thompson JL, Till JE, Yoder C, Zeitlin C. Dose reconstruction for the million worker study: status and guidelines. Health Phys. 2015 Feb;108(2):206-20. [PubMed Citation]
  3. Till JE, Beck HL, Aanenson JW, Grogan HA, Mohler HJ, Mohler SS, Voilleque PG. Military participants at U.S. Atmospheric nuclear weapons testing--methodology for estimating dose and uncertainty. Radiat Res. 2014 May;181(5):471-84. [PubMed Citation]
  4. Till JE, Grogan HA, Mohler HJ, Rocco JR, Rood AS, Mohler SS. An integrated approach to data management, risk assessment, and decision making. Health Phys. 2012 Apr;102(4):367-77. [PubMed Citation]
  5. 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. Annals of Internal Medicine 2004 Jun 15;140(12):1037-51. [PubMed Citation]
  6. Population Monitoring in Radiation Emergencies: A Guide for State and Local Public Health Planners, Second Edition, April 2014. (PDF - 1.02 MB) (HHS/CDC)
  7. Biodosimetry Based on Acute Photon-Equivalent Exposure (PDF - 108 KB)
  8. Relationship between Time to Onset of Vomiting and Dose over a Range of 2 - 10 Gy (PDF - 133 KB)

Retrospective Assessment of Dose Using Unconventional Devices

  1. Note
    • These references are provided for information only and are not endorsed by REMM or any department or agency of the US government.
    • Newer smartphones and other devices and software algorithms will also need to be assessed and validated before they can be relied upon during an actual incident.
  2. Wagner E, Sorom R, Wiles L. Radiation Monitoring for the Masses. Health Phys. 2016 Jan;110(1):37-44. [PubMed Citation]
  3. Ekendahl D, Bulánek B, Judas, L. Comparative measurements of external radiation exposure using mobile phones, dental ceramic, household salt, and conventional personal dosemeters. Radiation Measurements 2015;72:60-65.