The time required to identify those individuals who have received a significant dose of radiation is crucial as treatments for radiation are more effective the earlier they are administered.
About Radiological Event
A radiological event refers to an incident involving the release of radioactive materials, which can lead to exposure to harmful radiation levels. Examples include Improvised Nuclear Devices (INDs) or reactor accidents.
- Potential Impact:
- Health Risks: Exposure to significant doses of radiation can cause acute radiation sickness, long-term health effects, and increased cancer risk.
- Environmental Contamination: Radioactive materials can contaminate air, water, and soil, posing risks to the ecosystem and human health.
- Post-Radiological Event Response:
- Identification and Treatment of Radiation Exposure: Determine who has received a significant dose of radiation. Administer newly approved drugs for radiation sickness to those individuals.
- Reassurance and Management of Unaffected Individuals: Address the concerns of individuals who have not received a significant dose but are extremely worried.
- Prevent unnecessary hospital visits by these individuals, avoiding the overwhelming healthcare facilities.
- Rapid Dose Assessment: Conduct assessments of radiation doses received by tens or hundreds of thousands of individuals.
- Complete these assessments within a few days to ensure timely identification and treatment.
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About Biodosimetry
Biodosimetry is a method used to estimate the amount of radiation a person has been exposed to.
- Purpose: Determine radiation exposure based on biological changes.
- Biological Samples Used: Blood, urine, hair.
- Application: Particularly useful in radiological events without personal radiation monitoring devices.
- Systems for measuring DNA damage:
Basis
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Dicentric Chromosome Assay (DCA)
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Cytokinesis Block Micronucleus Assay (CBMN)
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Gamma-H2AX Assay
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| Mechanism: |
- DNA in blood cells breaks and repairs within hours.
- Incorrect repairs join fragments from different chromosomes.
- Forms Dicentric Chromosomes (DC) with two centromeres.
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- White blood cells divide and are arrested before complete division.
- Forms a cell with two nuclei.
- Radiation exposure causes DNA ejection during division, forming a micronucleus.
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- Measures the phosphorylated form of specific histone protein (gamma-H2AX).
- Can segregate exposed from unexposed and low dose versus high dose.
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| Procedure: |
- Cultivate lymphocytes from exposed individuals to initiate division.
- Spread chromosomes on a slide and stain.
- Count DCs under a microscope or in captured high-magnification images.
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- Slightly simpler to perform and score compared to DCA.
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- Does not require cell culturing.
- Must be performed within 24 hours due to histone phosphorylation kinetics.
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| Time Frame: |
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- 3 days (requires longer cell culturing).
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Need for Reducing Time to Report Radiation Dose
Early administration of radiation sickness treatments is crucial for patient outcomes. Rapid reporting allows timely intervention to maximize treatment effectiveness.
- Critical for Treatment Effectiveness: Early administration of radiation sickness treatments enhances their efficacy. Same-day reporting of radiation dose is crucial for timely intervention.
- Current Limitations of Assays: DCA and CBMN Assays require cell culturing for 2-3 days, delaying dose assessment.
- Accelerated Assay Development: Premature Chromosome Condensation (PCC) Assay treats cells with specific Kinases to condense chromosomes rapidly, bypassing the need for culturing. Potentially provides same-day dose estimates.
- Advancements in Technology: High-Throughput Screening (HTS) Platform implementation is aimed at reducing assay time to under 4 hours. Enhances efficiency in rapid radiation dose assessment.
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Conclusion
Establish community reception centers post-incident, conduct point-of-care biodosimetry for rapid assessment, followed by lab-based assays for dose estimation and long-term health monitoring.
July 5, 2024