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Limitations in the assessment of radon dose: the role of direct activity measurements

Limitations in the assessment of radon dose: the role of direct activity measurements J ohn Kalef -Ezra, S tratos Valakis M edical Physics Laboratory, University of Ioannina. ANNUAL RADIATION BURDEN OF THE MEAN GREEK ADULT ~5 mS v. _______________ _________________ ________

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Limitations in the assessment of radon dose: the role of direct activity measurements

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  1. Limitations in the assessment of radon dose: the role of direct activity measurements JohnKalef-Ezra, StratosValakis Medical Physics Laboratory, University of Ioannina

  2. ANNUAL RADIATION BURDEN OF THEMEAN GREEK ADULT ~5 mSv ________________________________________ sourceED source ED natural (mSv) man made(mSv)_ cosmic radiation~0.3 plane radiographs0.10 external spaces~0.1 fluoroscopy0.01 internal spaces~0.5 interventional proc. 0.13 internal radioactivity ~0.2 scintigraphic exams 0.11 contamination due to CT examinations 1.47 radon and its progeny 1.7 radiation workers ~0.3 other sources ~0.2 total ~2.7 ~2.3 GAEC, 2015 BENEFIT RISK

  3. INDOOR222Rn CONCENTRATION AT UI/MPL (COLD PERIOD OF THE YEAR) ____________________________________room floorCRn,air(Bq/m3)_ office #1 ground62office #2 ground 109_ store room #1 ground133 store room #2 ground198 _____ lab room #1 1stfloor62 lab room #2 1stfloor 112lab room #3 ground 340(147/60) _ measurements by GAECMean 222Rn at the Ioannina University Campusbuildings:floor:ground105Bq/m3,higher63Bq/m3(Ioannideset al 2009)

  4. EFFECTIVE DOSE DUE 222Rn INHALATION ED= CRn,airxDFxF

  5. vs

  6. Ventilation rate (m3/h) ________________________________________ _________________________ _ ____ “average” adult male female ___ resting (sleeping) 0.45 0.32 sitting (awake) 0.54 0.39 light exercise 1.5 1.3 heavy exercise 3.0 2.7 ___ ___ METABOLISM uptake: ~ proportionaltoblood flow retention, T1/2: * vs 3.82 d 4.5 min (blood) 41min(interstitialfluid) 3.4h(intracellularfluid) 18 h (adipose tissue) * Harley, Jetter, Nelson: Environ Int 7: 573-84 (1994)

  7. THE LONG “JOURNEY” OF RADON PROGENY IN OUR BODY nanoparticles coarse particles

  8. WHOLE BODY COUNTINGOF A VOLUNTEER AT UIMPL spectrum from a single detector 0.242 214Pb 0.3 0.410 214Bi 40K 0.609 214Bi 1.46 1.76 226Ra 222Rn 218Po 214Pb 214Bi 214Po 210Pb 214Pb (T1/2~27 min), Eγ(keV): 242(7.5%), 295 (19.2%), 352 (37%) 214Bi(T1/2~20min), Eγ(keV): 609(46%),1120(15%),1238(6%),1764(16%)

  9. WBC / IUMPL phantom measurement in vivo measurement Kalef-Ezra J, Valakis S, Soupsanas T: Radiation Protection Dosimetry144: 415-418 (2011) Valakis S, Pallada S, Kalef-Ezra J: Health Physics 107: 36-46 (2014)

  10. TBBi(n=65) arithmetic mean: 115 Bq geometric mean: 101 Bq standard deviation: 99 Bq coefficient of variation: 56% ____ Total body214Βi in healthy volunteers October to April, 20-65 y, residing at <5 km from UIC no recent: heavy exercise, heavy meal, smoking,… ___________________________________________________________________________________ lower TBBi in June than in April (n=14x2) _________________________ TBBi: male>female TBBi/BM: NS _____________________________ age influence: NS Kalef-Ezra, Valakis : Direct total body 214Bi…J. Radiological Protection (in press)

  11. Total body 214Bi BODY COMPOSITION ________________________________________group men (n=24) women (n=24) p__age (y)34.5+16.5 (26) 34.3+15.4 (28) 0.96BM (kg) 85 + 11 (87) 66 + 14 (63) <0.001ΤΒΒi (Bq) 153+62 (169) 97 + 61 (79) 0.003FM (kg)23.3+ 8.6(23.2)23.3+ 8.7(22.5)0.68FFM(kg)61.9+ 7.7 (63)42.7+ 6.6 (41)<0.001% FM/BM26.8+7.8(23.2) 34.4+6.7(36.0)0.001ΤΒΒi/BM(Bq/kg)1.84+0.91(1.78) 1.49+0.91(1.28) 0.19ΤΒΒi/FM(Bq/kg) 7.95+5.89(6.26) 4.51+2.93(3.94) 0.014ΤΒΒi/FFM(Bq/kg)2.52+1.17(2.39) 2.31+0.98(1.98) 0.56_____________________________________________________________________ Kalef-Ezra J, Valakis S: J. Radiol. Protection (in press)

  12. Whole body 214Bi activity in a adult volunteer following visits to A cave versus the time between exit from the cave and measurement T½, eff same cloths: (37+9) min other cloths: (47+6) min T½ (CoMo 170) cloths – α: (39+2) min 53 Bq

  13. Successive 214bi measurements ΔT ~ 1.0 h, 22 male, 22 female 2nd TBBi< 1st TBBi (p<0.001) mean 2ndTBBi/ 1st TBBi = 0.78 ________________________________________________ Valakiset al, Proc. HNPS 2012

  14. BISMUTH-214 SOURCES 226ra ingestion222Rn ingestion222Rn inhalation218Po,214Pb,214Bi inhalation

  15. MODELING OF 214Bi SOURCES COLD PERIOD OF THE YEAR _____________________________source of 214BiTBBi(Bq)____________________women menmedian TBBi (cold period) 97 153_226ra ingestion 0.2 0.3222Rn ingestion NS NS222Rn inhalation 7 6.5218Po/214Pb/214Bi inhalation ??_ ??_

  16. RISK ASSESSMENT VIA RADON MEASUREMENTS? ED= CRn,airxDFxF

  17. WHOLE BODY COUNTING spectrum from a single detector 0.242 214Pb 0.3 0.410 40K 214Bi 214Bi 0.609 1.46 1.76 226Ra 222Rn 218Po 214Pb 214Bi 214Po 210Pb 214Pb (T1/2~27 min) Eγ(keV): 242(7.5%), 295 (19.2%), 352 (37%) 214Bi(T1/2~20min) Eγ(keV): 609(46%),1120(15%),1238(6%),1764(16%)

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