science Med.pptx byyy dddddddddddddddddddd

U want it 😌

1. Biodosimetry 1

2. Content Biodosimetry Accidental Dosimetry Physical Dosimetry Clinical Dosimetry Biological Dosimetry Dicentric Assay (Standard Dicentric Analysis) Translocation Assay (FISH) Premature Chromosome Condensation (PCC) Assay Micronucleus (MN) Assay Glycophorin A (GPA) Somatic Cell Mutation Assay Biophysical Assay (ESR) 2

3. What is Biodosimetry ? The use of physiological, chemical or biological markers of exposure of human tissues to ionizing radiation for the purpose of reconstructing doses to individuals or populations. 3

4. Why do we need biodosimetry ? It is a tool to assess the likelihood of developing Acute Radiation Syndrome (ARS) and its clinical severity. Facilitate short-term triage (degrees of urgency), including where the patient should be treated. Assess the risk of long-term consequences from radiation exposure. Suggest countermeasures that will be needed to treat ARS 4

5. Accidental Dosimetry R efers to the measurement and assessment of radiation exposure that occurs as a result of unexpected or unplanned events involving radiation sources Involves the estimation of radiation doses received by individuals who were not intended to be exposed to radiation or were exposed to higher doses than anticipated 5

6. Accidental Dosimetry Typically, relevant in situations such as nuclear accidents, radiation spills, unintended radiation exposures in medical or industrial settings A ims to determine the amount of radiation to which individuals were exposed and to assess the potential health risks associated with that exposure 6

7. 7

8. Clinical Dosimetry 8 Method of calculation of the absorbed dose based on clinical presentation Vomiting Using Early Changes in Lymphocyte Counts Using Granulocyte Count

9. Biological Dosimetry 9 An internationally approved method to quantify exposure and to perform a dose assessment following a suspected radiation overexposure Implies different cytogenetic assays

10. Biological Dosimetry 10 Dicentric Assay Based on the principle that radiation exposure causes DNA strand breaks During repair of DNA strand breaks, mis-repair of 2 chromosomes and abnormal chromosome replication can lead to dicentric chromosomes, that is, a chromosome with 2 centromeres

11. Biological Dosimetry 11 Dicentric Assay Increases in radiation dose produce increasing numbers of dicentric chromosomes A ccurate method for dose estimation with sensitivity threshold of about 0.1 Gy for whole body low LET radiatio n

12. Biological Dosimetry 12 Dicentric Assay Dicentrics are unstable and lymphocytes carrying aberration elimininated with time A verage lifetime 150-220 days , depending o n dose U seful only within few months of irradiation

13. Biological Dosimetry 13 Translocation Assay (FISH) In retrospective dosimetry and chronic exposure reciprocal translocations are use for dose measurements Translocations( a chromosomal abnormality whereby there's a break in the chromosome, one particular chromosome, and that chromosome will then fuse to a different chromosome ) are stable in cell division; thus, the yield does not fall with time

14. Biological Dosimetry 14 Translocation Assay (FISH) Typically detected using specific whole chromosome DNA hybridization probes and Fluorescence In Situ Hybridization (FISH) FISH is a laboratory technique for detecting and locating a specific DNA sequence on a chromosome

15. Biological Dosimetry 15 Premature Chromosome Condensation (PCC) Assay Premature chromosome condensation (PCC) is a sensitive and unique way to detect interphase chromosome damage and its recovery in cells irradiated with ionizing radiation Mitotic inducer cells are isolated using chemical and physical techniques (CHO)

16. Biological Dosimetry 16 Premature Chromosome Condensation (PCC) Assay Test cells/ human lymphocytes are fused with CHO cells using Polyethyline Glycol (PEG) Interphase DNA of test cells condense into chromatids/ chromosome-like structures

17. Biological Dosimetry 17 Micronucleus (MN) Assay Not specific to radiation exposure More difficult to discriminate between total and partial body exposure High dose of radiation interferes with cell division High baseline frequency and age dependency make reliability of assay questionable

18. Biological Dosimetry 18 Glycophorin A (GPA) Somatic Cell Mutation Assay Performed by two color immunofluorescence flow cytometry on peripheral blood erythrocytes. Based of measuring number of variants of erythrocytes, which display phenotype consistent with loss expression of GPA (M) Sensitivity threshold around 0.2-0.25 Gy

19. Biological Dosimetry 19 Biophysical Assay (ESR) Persistent free radicals formed in solid matrix biomaterial (dental enamel/ nail clippings/ hair) from accidentally exposed victim can be detected via Electron Spin Resonance (ESR) Provide reliable biophysical dose estimates and partial body exposure information

20. Thank you! 20