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

Explore challenges in assessing radon dose and the importance of direct activity measurements in medical physics labs at University of Ioannina. Analyze the annual radiation burden in Greek adults, radon concentration, effective dose due to inhalation, and radon progeny in the body. Study the journey of radon progeny, whole-body counting, and body composition effects. Discuss risk assessment via radon measurements.

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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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