1

VERIFICATION OF THE CHERNOBYL VERIFICATION OF THE CHERNOBYL REGISTRY DOSIMETRIC DATA AS A REGISTRY DOSIMETRIC DATA AS A

RESOURCE FOR EFFICIENT RESOURCE FOR EFFICIENT DOSIMETRIC SUPPORT SOLUTION DOSIMETRIC SUPPORT SOLUTION FOR POST-CHERNOBYL HEALTH FOR POST-CHERNOBYL HEALTH

EFFECTS STUDIESEFFECTS STUDIES

Vadim Chumak

Scientific Center for Radiation Medicine AMS Ukraine

2

Total number of liquidators Total number of liquidators (UNSCEAR, 2000)(UNSCEAR, 2000)

Countryand period

Number ofclean-up workers

Percentage for whom dose is known

Belarus 1986-1987 1986-1989

31 00063 000

2814

 

Russian Federation 1986 1987 1988 1989 1986-1989

69 00053 00020 5006 000

148 000

5171837363

 

Ukraine 1986 1987 1988 1989 1986-1989

98 00043 00018 00011 000170 000

4172798656

3

Inventory of dosimetric databasesInventory of dosimetric databases Only about 47% records in SRU, which are related

to liquidators of 1986-1990, contain individual doses (51% for 1986-1987)

95% of ODR in SRU belong to military liquidators Six IDM databases related to civilian liquidators

(ChNPP, AC-605, PA “Combinat”) – 168,394 dose records – failure to link with SRU data

Paper archives of the Ministry of Defense were converted into electronic databases (ca.50,000 records) – good overlap and coincidence with SRU data

4

Frequency histogram of doses of Frequency histogram of doses of military liquidators (“partisans”) of 1986military liquidators (“partisans”) of 1986

0

1000

2000

3000

4000

0 50 100 150 200 250 300

Cumulative dose, mSv

Fre

quen

cy, p

erso

ns

5

Frequency histogram of individual daily Frequency histogram of individual daily doses of military liquidators of 1986doses of military liquidators of 1986

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25 30

Daily dose, mSv

Fre

quen

cy, p

erso

ns

6

Normalized probability plot for distribution of Normalized probability plot for distribution of daily doses of military liquidators daily doses of military liquidators

(“partisans”) of 1986 (HLN hypothesis)(“partisans”) of 1986 (HLN hypothesis)

0

20

40

60

80

100

0 20 40 60 80 100

Probability (experimental data)

Pro

babi

lity

(HLN

dis

trib

utio

n)

7

Experimental dependence of entropy Experimental dependence of entropy coefficient on increment of histogram coefficient on increment of histogram

(solid line) and modeled calibration (solid line) and modeled calibration dependenciesdependencies

8

Dosimetry methodsDosimetry methods

TLD monitoring with a personal dosimeter

“group-dosimetry” – one dosimeter per group of workers

“group-estimation” – one pre-calculated dose to a whole group of workers

9

EPR dosimetry:EPR dosimetry:metrological parameters of metrological parameters of

SCRM protocolSCRM protocol

Sensitivity threshold – 50 mGy

Simplified error propagation model:+ 25 mGy for dose <250 mGy+ 10% for dose >250 mGy

10

Cutting tooth into Cutting tooth into lingual and buccal partslingual and buccal parts

11

Samples for analysis: Samples for analysis: Tooth acquisition network in UkraineTooth acquisition network in Ukraine

Health M inistryof Ukraine

D neprope trovsk

P oltava

C hernyhiv K harkiv

Zaporizhya

C herkasy

K iev

Central b ioprobe bank

Bioprobe section Database sectionconservation ep idem iologyregis tra tion o f incom ing probesstorage m ed icinetracing of the sam plessam ple preparation socia l serv icestorage o f reconstruc ted dosesaccess fo r analysis exposed ind iv idualsre trieva l and output of doses

. . .. . .. . .. . .

EPR-dosim etrym ethodo logica l

centerEPR-dosim etry lab

Consum erso f dosim etric in fo rm ation

12

Samples for analysis: Samples for analysis: results of tooth collection effortresults of tooth collection effort

Teeth are being collected in 167 hospitals by 314 dentists

7,657 teeth were collected over the period of operation (as per March 1, 2006)

4,635 liquidators had donated teeth 3,511 teeth are appropriate for high precision

EPR dosimetry 805 doses were reconstructed including 638

with HPT

13

Calibration against EPR dosimetry:Calibration against EPR dosimetry:Distribution of ODR/EPR ratioDistribution of ODR/EPR ratio

0

5

10

15

20

25

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 Еще

ODR/EPR ratio

Fre

qu

en

cy

14

Retrospective assessment of bias Retrospective assessment of bias and uncertainty of ODR (2002)and uncertainty of ODR (2002)

92 subjects with group assessment ODR (military liquidators of 1986-1987)

EPR used as a reference (point dose estimate) Ratio ODR/EPR is considered as model

uncertainty distribution Parameters of distribution

(2003 data for 119 subjects): GM – 0.39 (0.43)

GSD – 2.14 (2.05)

15

Plan of validation of official Plan of validation of official dose records in SRUdose records in SRU

Collection of teeth from liquidators Stratification of military liquidators by

category of dosimetric dataApplication of EPR dosimetry as a

reference for recalibration of ODRElaboration of criteria for identification of

falsified dose values

16

Expected outcomeExpected outcome

Ca.60,000 validated and re-calibrated Official Dose Records

Individual uncertainty distributions (possibility to derive point estimate along with uncertainty)

Dosimetric database for SRU members to be available for researchers of post-Chernobyl medical effects

17

Thank you!Thank you!