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PRINCIPLES OF D ETECTION OF RADIATION INJURES. Accidental dosimetry. BIOLOGICAL DOSIMETRY. PHYSICAL DOSIMETRY. CLINICAL DOSIMETRY. CYTOGENETIC DOSIMETRY Dicentrics, FISH, PCC, MN A . DOSE RECONSTRUCTION , Personal Dosimeters. NAUSEA, V OMITING, BLOOD CELLS COUNTS,

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Principles of d etection of radiation injures l.jpg

PRINCIPLES OF DETECTIONOF RADIATION INJURES


Accidental dosimetry l.jpg
Accidental dosimetry

BIOLOGICAL

DOSIMETRY

PHYSICAL

DOSIMETRY

CLINICAL

DOSIMETRY

CYTOGENETIC DOSIMETRY

Dicentrics,FISH,

PCC, MNA

DOSE

RECONSTRUCTION,

Personal Dosimeters

NAUSEA, VOMITING,

BLOOD CELLS COUNTS,

SKINREACTIONS...

OTHER BIOINDICATORS


Physical dosimetry l.jpg
Physicaldosimetry


Instruments for d etecting and m easuring r adiation l.jpg
Instruments for detecting and measuring radiation

  • Survey meters

    • Geiger-Mueller (GM) instruments

    • Ionization chamber instruments

    • Scintilation instruments

  • Laboratory counters

  • Personnel dosimeters

    • Photographic film dosimeters

    • Thermoluminescent dosimeters

    • Pocket dosimeters


Primary u se of r adiation i nstrument l.jpg

Level of radioactive contamination

Radiation dose rate in area

Identity and quantity of radioactive material

Accumulated dose to individuals inarea

Primary use of radiation instrument

Survey meters

Laboratory counters

Personnel dosimeters


Personnel d osimeters l.jpg
Personnel dosimeters

Electronic dosimeter

Film

badge

TLD


Photographic f ilm d osimeters l.jpg

Advantages

Permanent record

Energy and nature of exposure

Cost

Disadvantages

Energy dependence

Fading

Size

Photographic film dosimeters



Pocket d osimeters l.jpg
Pocket dosimeters


Digital p ocket d osimeter l.jpg
Digital pocket dosimeter



Clinical and laboratory sings of acute radiation syndrome l.jpg
Clinical and laboratory sings of acute radiation syndrome

  • Prodromal clinical effects

    • Time of onset

    • Degree of symptoms

  • Haematological changes

    • Lymphocyte counts

    • Leukocytes counts

    • Biological dosimetry


Clinical dosimetry at radiation vomiting l.jpg
Clinicaldosimetry at radiation vomiting

Crude estimate of absorbed dose obtainable from clinical presentation

  • Vomiting

    • Onset: 2 h after exposure or later

    • Onset: 1-2 h after exposure or later

    • Onset: earlier than 1 h after exposure

    • Onset: earlier than 30 min after exposure

MILD ARS (1-2 Gy)

MODERATE ARS

(2-4 Gy)

SEVERE ARS (4-6 Gy)

VERY SEVERE ARS

(6-8 Gy)


Radiation d ose u nder 5 gy l.jpg
Radiation dose under 5 Gy

  • No immediate life-threatening hazard exists

  • Prodromal symptoms of moderate severity

    • Onset > 1 hour

    • Duration < 24 hours


Fatal r adiation l.jpg
Fatal radiation

  • Nausea and vomiting within minutes(during the firsthour)

  • Within hours (on the first day):

    • Explosive bloody diarrhoea

    • Hyperthermia

    • Hypotension

    • Erythema

    • Neurological signs


Triage c ategories of r adiation i njuries a ccording to e arly s ymptoms l.jpg
Triage categories of radiation injuries according to early symptoms


Guide for management of radiation injuries on the basis of early symptoms l.jpg

No vomiting

Vomiting 2-3 h

after exposure

Vomiting 1-2 h

after exposure 

Vomiting earlier than 1 h, other severe symptoms, like hypotension

hyperthermia,

diarrhea, oedema, erythema, CNS symptoms

< 1 Gy

1-2 Gy

2-4 Gy 

> 4 Gy

Outpatient with 5-week surveillance

Surveillance in a general hospital (or outpatient for 3 weeks) followed by hospitalization

Hospitalization in a hematological department 

Hospitalization in a well equipped hematological or surgical department with transfer to a specialized centre for radiopathology

Guide for management of radiation injuries on the basis of early symptoms



Laboratory d osimetry u sing e arly c hanges in l ymphocyte c ounts l.jpg
Laboratory exposuredosimetry using early changes in lymphocyte counts


Change of lymphocytes counts depending o n dose o f acute whole body exposure l.jpg

Degree of ARS exposure

Dose (Gy)

Lymphocyte counts (cells/L)

2 days after first exposure

Preclinical phase

Mild

Moderate

Severe

Very severe

Lethal

0.1-1.0

1.0-2.0

2.0-4.0

4.0-6.0

6.0-8.0

>8.0

1500-2500

700-1500

500-800

300-500

100-300

0-50

Change of lymphocytes counts depending on dose of acute whole body exposure


Laboratory d osimetry u sing g ranulocyte c ounts l.jpg
Laboratory exposuredosimetry using granulocyte counts


Cytogenetic dos imetry l.jpg
Cytogenetic dos exposureimetry


Cytogenetic dos imetry23 l.jpg
Cytogenetic dos exposureimetry

Analysis of chromosomal aberrations in peripheral blood lymphocytes - widely used biologicaldosimetry method forassessing radiation dose, especially useful

  • in persons not wearing dosimeters while exposed to radiation

  • in cases of claims for compensation for radiation injuries not supported by unequivocal dosimetric evidence

  • for validation of occupational radioprotection cases involving suspected low-dose exposures


B iophysical b ackground to c hromosome d amage l.jpg
B exposureiophysical background to chromosome damage

High LET

*****************************

* * * * * * * *

Low LET


Classification of c hromosomal a berrations l.jpg
Classification of exposurechromosomal aberrations

Asymmetrical

(UNSTABLE)

Breaks

Symmetrical

(STABLE)

Centric

Ring

Inversion

Intrachange

Interchange

Translocation

Dicentric


Biological d ose a ssessment u sing s tandard d icentric a nalysis l.jpg
Biological exposuredose assessment using standard dicentric analysis

  • Introduced by M. Bender in 1964

  • Isolated lymphocytes stimulated by phytohaemagglutin (PHA) into mitosis

  • Arrest of metaphase using colchicine

  • Scoring of dicentric chromosome aberrations in metaphase spreads


Dicentric c hromosome a berrations in m etaphase s preads l.jpg
Dicentric exposurechromosome aberrations in metaphase spreads

dic

f

dic

f

f

f


Dose curves at high let and low let radiation l.jpg
Dose exposurecurves at high LET and lowLET radiation

Y = A+aD + bD2


Dose curves at a cute and c hronic e xposure l.jpg
Dose exposurecurvesatacute andchronic exposure

 particles

Fast neutrons

(High LET)

Gamma rays,

X-rays acute exposure

(Low LET)

Y = c + aD

Y = c + aD + bD2

Effect

Dicentric yield

Y = c + aD

Gamma rays

X-rays chronic exposure

(Low LET)

Dose


Dose es timati on of a partial body radiation e xposure non uniform irradiation l.jpg
Dose es exposuretimationof a partial bodyradiation exposure (non-uniform irradiation)


D icentric a ssay l.jpg
D exposureicentric assay

  • Most accurate method for dose estimation with sensitivity threshold of about 0.1 Gy for whole body low LET radiation

  • Especially useful

    • in cases where dosimeter not used, e.g. radiation accident

    • to support physical dosimetry results in radiation protection and safety practice

    • to determine partial body exposure not detected by locally placed dosimeter


Limitations of d icentric a nalysis for d ose e stimation l.jpg
Limitations of exposuredicentric analysis for dose estimation

  • Dicentrics are unstable and lymphocytes carryingaberration elimininated with time (average lifetime 150-220 days, depending on dose), hence can underestimate magnitude of dose

  • Method useful only within few months of irradiation


Translocation assay l.jpg
Translocation assay exposure

  • Inretrospective dosimetryandchronic exposurereciprocal translocations used for dose assessment

  • Translocations consideredstablein cell division so yield should not fall with time

  • Typically detected using specific whole chromosome DNA hybridization probes and FISH methodology


Stable c hromosome a berration a nalysis with g banding l.jpg
Stable exposurechromosome aberration analysis with G-banding

An idiogram showing the banding patterns of individual chromosomes by fluorescent and Giemsa staining

A normal G banded male karyotype


Stable c hromosome a berration a nalysis with fish l.jpg
Stable exposurechromosome aberration analysis with FISH

Translocation

Deletion


Applicability of s table c hromosome a berration a nalysis for b iological d osimetry l.jpg
Applicability of exposurestablechromosome aberration analysis for biological dosimetry

  • Method based on scoring stable chromosome aberrations (translocations and insertions) detected with fluorescent in-situ hybridization of whole chromosomes

  • Requires complex procedures and technical equipment

  • May be use decades after exposure

  • Sensitivitythreshold a few cGy but method not feasible for doses less than 0.2 Gy because of expense and time needed for analysis

  • Spontaneous level of stable chromosome aberrations not well established


Premature c hromosome c ondensation pcc a ssay l.jpg
Premature exposurechromosome condensation (PCC) assay

  • Initially introduced by Johnson and Rao (1970)

  • Mitotic-inducer cells (i.e. CHO) isolated using chemical (colcemid) and physical (rapid shaking of flask) technique

  • Test cells (i.e. human lymphocytes) fused with CHO cells using polyethylene glycol (PEG)

  • Interphase DNA of test cells condense into chromatid/chromosome-like structures (46 for non-irradiated human cells)


Pcc t echnique l.jpg
PCC exposuretechnique

CHINESE HAMSTER

OVARY (CHO) CELLS

(Grown in BrdU)

COLCEMID

MITOTIC SHAKE OFF

(METAPHASE CELLS)

FUSE IN PEG

PERIPHERAL BLOOD

CHO

LYMPHOCYTES

FICOL SEPARATION

Incubate 1 h

(Medium+PHA+Colcemid)

PCC


Pccs and fish l.jpg
PCCs and FISH exposure

Irradiated cells

with excess break

Unirradiated control


Estimation of i rradiated b ody f ractions l.jpg
Estimation of exposureirradiated body fractions


Applicability of pcc assay for b iological d osimetry l.jpg
Applicability of PCC exposureassayfor biological dosimetry

  • Dose estimates obtainable within48 hours of receipt of blood inlaboratory

  • Radiation inducedmitotic delay does not interfere with assaysince performed on interphase nuclei and does not require cell division

  • Method envisioned applicable afterpartial-body/ supra-lethal exposure and improves detection level oflower doses


Micronucleus a ssay l.jpg
Micronucleus exposureassay

Cytochalasin B


Micronucleus and n ucleoplasmic b ridges in b inucleated c ells l.jpg
Micronucleus exposure and nucleoplasmic bridges in binucleated cells

B

A


Micronucleus a ssay with p ancentromeric p robe l.jpg
Micronucleus exposureassay with pancentromeric probe

A

B

centromere positive

centromere negative


Application of micronucleus a ssay for b iological d osimetry l.jpg
Application of exposuremicronucleusassay for biological dosimetry

  • Micronucleus not specific toradiation exposure

  • Discrimination between total and partial body exposure moredifficult

  • High doses of radiation interfere with cell division

  • High baseline frequencyand age dependency make reliability of assay questionable


Glycophorin a gpa s omatic c ell m utation a ssay l.jpg
Glycophorin A (GPA) exposuresomatic cell mutation assay

  • Performed by two-color immunofluorescence flow cytometry on peripheral blood erythrocytes

  • Based of measuring N/0 variants of erythrocytes, which display phenotype consistent with loss of expression of GPA (M) allele

  • Can be performed only on individuals heterozygous at this locus that codes for the N/M blood group antigens (approximately half of population)

  • Prompt but requires complex and expensive equipment

  • Sensitivity threshold about 0.2-0.25 Gy


Application of gpa a ssay for b iological d osimetry l.jpg
Application of GPA exposureassay for biological dosimetry

Relationship between glycophorin A mutant frequency in red blood cells and radiation dose for about 1200 A-bomb survivors


Biophysical assays esr electron spin resonance l.jpg
Biophysical assays exposure - ESR(electron spin resonance)

  • Persistent free radicals formed in solid matrix biomaterial (e.g. dental enamel, nailclippings, hair) from accidentally exposed victim can be detected via ESR

  • Measurements provide reliable biophysical dose estimates and partial body exposure information

  • In some circumstances, certain clothing material, particularly hard plasticsand buttons, may be measured and absorbed dose estimated


Characterization of b iological d osimetry m ethods l.jpg
Characterization of exposurebiological dosimetry methods


Summary of lecture l.jpg
Summary of lecture exposure

  • In radiation accidents, important to estimate the absorbed doses in victims to plan appropriate medical treatment

  • In most accidents, physical dosimetry of absorbed dose is not possible. Even where possible, important to confirm the estimates by other methods

  • Most commonly used method cytogenetic analysis of chromosomal aberration in peripheral blood lymphocytes using dicentrics, translocations, PCC and micronuclei assays


Lecture is ended l.jpg
Lecture is ended exposure

THANKS FOR ATTENTION

In lecture materials

of the International Atomic EnergyAgency (IAEA),

kindly given by doctor Elena Buglova, were used


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