Radiological Accidents in Georgia

1. Radiological Accidents in Georgia Lecture Module 15

2. The dicentric assay 48 h Observation of 500 metaphases in 2-2.5 days scoring Cell culture Spreading Dicentrics acentrics Blood Processing 2 x 5 ml blood collected on heparin 3 days 500 cells 48 hours 1 day 1 hour 50 cells

3. Cobalt-60 (0.1 Gy/min) 1,8 5 Cobalt-60 (0.5 Gy/min) 1,6 4,5 Bare source (n/g=0.86) X-Ray (0.1 Gy/min) 4 1,4 Lead shield (n/g=5.6) Caesium (0.5 Gy/min) 3,5 1,2 CH2 shield (n/g=0.12) 3 Yield of dicentrics and centric rings per cell Yield of dicentrics and centric rings per cell 1,0 2,5 0,8 2 0,6 1,5 0,4 1 0,2 0,5 0,0 0 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 Dose (Gy) Dose (Gy) Dose effect curves WHOLE BODY DOSE

4. Summary of the different strategies for dealing with a few or many patients Expertise (Priority to the dose assessment) Emergency w/o population triage (Priority to the medical evaluation) Emergency w population triage (Priority for the distribution in categories) Clinical symptoms Biological tests (hematological analysis, biochemical data, HLA, etc.) Physical dosimetry Biological dosimetry quick but not precise Biological dosimetry very precise Medical team Biological dosimetry more precise Clinical decision & treatment Time Time

5. Influence of the number of cells analysed on the precision of dose estimation Confidence intervals at 95 %: include the “true” value of the dose Triage based on 50 cells: 1 hour More precise dose estimation: 2-3 days

6. Dose reconstruction by biological dosimetry for the accident at Lilo (Georgia, 1997)

7. Location in Georgia LILO, 1997

8. Lilo military training center • 1997: 11 Georgian soldiers developed radiation induced skin lesions and acute radiation syndrome 12 radioactive sources (Cs-137, Co-60, Ra-226) abandoned at different locations in a former training Russian military camp, some in this underground shelter. The most irradiated victim (33 patches on his body)

9. LILO: accident circumstances (1) • Source container seems to have been opened by patient AN, but the source remained inside for some time. Then the source was placed in pocket of EP’s coat. The coat was borrowed regularly leading to irradiation of other persons. TK and CG shared the same room with AN and EP and all used the coat, with the source in a pocket, as a night time bed blanket. • Irradiation occurred from mid 1996 to April 1997 • Discovery of the exposures was in August 1997

10. LILO: accident circumstances (2) • 11 people with different levels of expsoure • The 4 most exposed people were hospitalized in France, the 7 others in Germany • All patients in France suffered from lymphopenia and nausea • AN suffered from contractures affecting the hands and lesions on the abdomen • TK displayed a deep lesion on the right thigh • EP displayed 33 patches on the trunk and thighs • CG had hand and thigh lesions

11. Results of the dicentric analyses • Analyses made in October 1997

12. Details of biological dosimetry by cytogenetics for the 4 most irradiated patients 4 patients hospitalized in France Analyses performed by 23/10/1997 Dicentric distribution Case Cells Dic Cr Ace 0 1 2 3 4 u-test Adu 502 55 4 24 456 39 5 2 0 4.68 Eli 518 80 4 25 453 50 15 0 0 3.61 God 500 19 1 15 481 19 0 0 0 -0.59 Kak 500 14 0 11 486 14 0 0 0 -0.43 Dic = dicentrics; Cr = centric rings; Ace = excess acentrics

13. Protracted/chronic exposure : correction by the G-function Initial dose-effect curve : Y= c + αD +βD2 For a protractedexposures the acute curveismodified by the G-function G(x) = 2/x2 [x-1+exp(-x)] where x= t/t0 t= the actual exposure time t0=2h Modified dose-effect curve : Y= c + αD +βG(x)D2

14. Corrected N ° Initial Dosesby Doses Doses ESR (Gy) (Gy) (Gy) 4.2 1 1.2 ND 5.9 2 1.6 4.5 1.5 3 0.7 1.4 1.1 4 0.5 1.5 0.2 5 0.1 ND 0.6 6 0.3 0.7 1.1 7 0.5 1.3 0.7 8 0.3 0.1 4.1 9 1.2 0.4 0.2 10 0.1 ND 0.6 11 0.3 0.1 Correction of cytogenetics results and comparison with ESR data ND = not done

15. Some follow-up data

16. Comparison of dicentric and translocation yields when patients were first sampled

17. FISH follow-up

18. Conclusion • Complex exposure scenario • Exposures protracted • Delayed discovery • Dicentric assay still possible • Linear dose response curve used • Reasonable agreement with ESR • Follow-up dicentrics reduced with time • Greater stability of translocations • Translocations probably reflect the bone marrow dose

19. The second accident Dose reconstruction by biological dosimetry for the accident at Matkhoji (Georgia, 1998)

20. The location MATKHOJI, 1998

21. Key-dates in the IAEA mission to Georgia 1. 4 August 1998 : Georgia requested assistance from the IAEA for radioactives sources found in and near Matkhoji. 10~14 August : IAEA team identified problems and needs. Three Cs-137 sources found: 150 GBq in a pit in a field 65 m from the main road dose rate: 0.15 mSv/h at 1 m. 3.3 GBq in an empty yard 4 m of the same road; dose rate: 0.3 mSv/h at 1 m. 0.17 GBq in a barn; dose rate: 15 µSv/h at 1 m. The pit was used as a swimming pool mainly by children and the empty yard as a playground. In the barn, the source was found close to the place where cows were milked each day.

22. 13 August : IAEA requested France to perform biodosimetry. 14 August : Difficulties for local medical team to identify the critical individuals. 18 August : France offered to send a physicist and a physician to help the Georgian medical team to identify the critical persons. 16 September: Hematological screening by local medical team on 800 suggested that 60 people could have received 0.2 Gy. 12~17 October 1998 : Georgia requested help through IAEA and a French team of two physicians, a physicist and a translator went to Georgia. Key-dates 2.

23. To collect information about the circumstances of the exposure directly from the Matkhoji people and the Georgian authorities. To make blood cell counts on local people, to detect leucopaenia. To blood sample some tens of people for biological dosimetry. People sampled: children using the pit and playground and people living in the barn. French team’s decisions

24. Timetable of the biodosimetry in Paris Quick triage: 50 cells per case: Saturday 17th October (day 0) 85 blood samples arrive in Paris First blood cultures Sunday 18th October (d1) Second blood cultures Monday 19th October (d2) Mitotic block and harvesting of the first cultures after 48 h Tuesday 20th October (d3) Mitotic block and harvesting of the second cultures after 50 h Wednesday 21st October (d4) Staining slides and starting triage scoring Thursday 22nd October to Monday 26 October (d5 - 7) Completed scoring, using six observers and an image analysis system Full analyses: increased scoring to 250 cells per case: From Tuesday 27th October to Thursday 17th December 1998

25. Summary of biodosimetry results • First triage step : 85 individuals, mainly children • On a basis of 50 cells scored per individual • 1 blood sample with two cells carrying one dicentrics each; • 1 blood sample with a cell carrying one dicentric; • 1 blood sample with a cell carrying two dicentrics. • 82 blood samples with no dicentrics • Conclusion : the dose estimation is within the 0 - 1 Gy range

26. Dicentric yields distribution

27. Matkhojl - Conclusions Biodosimetry indicated no individual whole-body dose above 0.3Gy. The highest doses were mostly to children who played in the former military camp close to the radioactive sources. From the local investigations it was impossible to reconstruct precise individual exposures. The haematology was normal, but this would only exclude doses > 1 Gy. The biodosimetry was the most quantitative technique possible and the results were good news for the people examined and more generally the whole population of Matkhoji.