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Radiation Protection in Laboratory work

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  1. RadiationProtection in Laboratorywork • Mats Isaksson, prof.Departmentofradiationphysics, GUmats.isaksson@radfys.gu.se

  2. Fundamental principles (ICRP) • Justification • Optimisation • Application of dose limits

  3. Fundamental principles (ICRP) • Justification • “Any decision that alters the radiation exposure situation should do more good than harm.”

  4. Fundamental principles (ICRP) • Optimisation • “The likelihood of incurring exposure, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking into account economic and societal factors.” • (The ALARA-principle)

  5. Fundamental principles (ICRP) • Application of dose limits • “The total dose to any individual from regulated sources in planned exposure situations other than medical exposure of patients should not exceed the appropriate limits specified by the Commission.” • N.B. ”… other than medical exposure of patients…” • ICRP-report 103 identifiesthree exposure situations: planned, emergency and existing

  6. Radiationdoses 1 • Absorbeddose (unit 1 Gy = 1 J kg-1) • Used in e.g. radiationtherapy to specify the dose to the tumor • Different radiationqualities(a, b, g, n) can cause different degree of harm – weightingnecessary

  7. Radiationdoses 2 • Equivalentdose (unit 1 Sv = 1 J kg-1) • Used to calculate the dose to a tissue or organ • Weightingfactors for different radiationqualities given by ICRP • Can be estimated by measurablequantitiese.g.personaldoseequivalent

  8. Radiationdoses 3 • Effectivedose (unit 1 Sv = 1 J kg-1) • Used to calculate the wholebodydose that gives the same detriment as the actualpartialbodydose • Enables a comparison of risk from different exposure distributions

  9. Radiationdoses 3´ • Illustration to effectivedose

  10. Radiationdoses 4 • Effectivedose (unit 1 Sv = 1 J kg-1) • Weightingfactors for different organs and tissues are given by ICRP • Can be estimated by measurablequantitiese.g.ambientdoseequivalent

  11. ”The bottom line” Effectivedose / mSv a-1 Medical diagnostics Caesium-137 Naturallyoccurring radionuclides in food Radon in indoor air K in the body Soil and building materials Cosmic radiation Smoker (and ex. smoker) Never-smoker Reindeer keepers Frequent air traveller Drinking water problem

  12. X-ray and nuclear medicine From ”Nuklearmedicin” by Sten Carlsson and Sven-Eric Svensson (available at http://www.sfnm.se/)

  13. Radiationsources • Radioactivesources • Unsealed – liquid, gas, powder • Sealed • Technicalequipment • X-raymachines • Accelerators

  14. Ionizingradiation from radioactive elements

  15. X-rayequipment Generation of x-rays X-rayspectrum

  16. Radiationsafety in the lab • Externalirradiation • Short range radiation, e.g. a, mostly harmless when the source is outside the body • b-emitters may cause severe skin damage if they are in contact with naked skin

  17. Radiationsafety in the lab • Internalirradiation • Radioactive substances in non-sealed sources (gas, liquid, powder) cause special concern • Can enter the body through ingestion, inhalation, wounds or through the skin

  18. Radiationsafety in the lab • Externalirradiation: Factors to be considered • Time – more time spent in the radiation field gives a larger radiation dose • Distance – inverse square law (for point source) • Shielding – shielding material depends on the source (a, b, g)

  19. Radiationsafety in the lab • Externalirradiation: Inversesquarelaw

  20. Radiationsafety in the lab • Externalirradiation: Inversesquarelaw

  21. Practical ALARA • Practicebeforeworkingwith the real source • Educationbeforework • Separateoffice and labwork • Wearprotectiveclothing and gloves • All labsshould be markedwithsigns • Eat, drink etcoutside the lab

  22. Radiationsafety in the lab • Externalirradiation: Shielding: b-range in mm H-3: 19 keV; C-14: 156 keV; S-35: 167 keV; P-32: 1711 keV

  23. Radiationsafety in the lab • Externalirradiation: Shielding: g HVL in mm I-125: 35 keV; Tc-99m: 140 keV; I-131: 365 keV; Y-88: 1836 keV

  24. Radiationsafety in the lab • Internalirradiation: Factors to be considered • Activity – the larger the activity the larger the radiation dose (for a given radionuclide) • Radionuclide – amount of energy per disintegration; type of radiation • Metabolism – element and chemical form determine the residence time in the body and concentration in organs

  25. Radiationsafety in the lab • Internalirradiation: Effectivehalf-life

  26. Radiationsafety in the lab • Classification of radionuclides • Class A: very high radiotoxicity (ex. a-emitters: Pb-210, Pu-238, Cf-252,…) • Class B: high radiotoxicity (Na-22, Ca-45, Co-56, Co-60, Sr-89, In-114m, I-125, I-131, Cs-137,…) • Class C: moderate radiotoxicity (C-14, Na-24, P-32, S-35, Ca-47, Cr-51, Fe-55, Fe-59, Co-57, Co-58, Zn-65, Y-90, I-123, Tl-201…) • Class D: lowradiotoxicity (H-3, C-11, Tc-99m,…)

  27. Deterministiceffects – approximatethresholdvalues • >0,1 Gy Effects on embryo and fetus • 0,5 Gy Temporarysterility, men • 2 Gy Cataract • 4 Gy Temporaryhair loss • 5 Gy Skin erythema • 6 Gy Permanent sterlility, men • 8 Gy Pneumonia • 2-12 Gy Permanent sterility, women

  28. Deterministiceffects – wholebodyirradiation • Lethaldose (50 % of exposed individualssurvive): 3-4 Gy • Acuteradiationsyndrome – bloodforming organs, gastro-intestinaltract & central nervous system

  29. Stochasticeffects – no threshold • Cancer and hereditaryeffects • Increasing risk with increasingdose • Risk factoronlyapplicable on a population level • LNT-hypothesis

  30. Laws and regulations • Strålskyddslagen SFS 1988:220 • Employers obligations • Workers obligations • Licencedemands • Waste handling demands • Medical examination • Young people • Strålskyddsförordningen SFS 1988:293

  31. Relevant regulations (SSM) • SSMFS 2010:2 Radioactivewaste • SSMFS 2011:2 Clearance of materials, premises, buildings och grounds • SSMFS 2008:25 Radiography • SSMFS 2008:51 Protection of workers and the public • SSMFS 2008:28 Laboratory work with unsealedradioactivesources

  32. License from SSM for work with ionizingradiation • Licensee: University of Gothenburg • Contact person Annhild Larsson • Radiationprotectionexpert (GU) Annhild Larsson • Radiationprotectionexpert (Rad. Phys.) Mats Isaksson • License valid to 2016-02-07

  33. SSMFS 2010:2 Radioactivewaste • Revised limits • Documentationkept for 5 years • Yearlyreportto SSM concerning releases tosewage

  34. SSMFS 2008:51: Dose limits (mSv) *) Will probably be revisedto20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv

  35. SSMFS 2008:51: Protectionof pregnant or breastfeedingwomen • Women in fertile agesshould be informedof the risks for the fetus • Pregnant womenhave the right to be relocated (if not, the effectivedoseto the fetusshould not exceed 1 mSvduring the rest of the pregnancy • Breastfeedingwomenshould not be exposedto a risk ofbeingcontaminated in the work

  36. SSMFS 2008:51Categorization • Protected area (”Skyddat område”) • Category B worker • localrules (could be given verbally) • signswith the text ”skyddat område” and typeof source • Category B (max activity per workactivity) • Gamma emittingradioniclides: < 100 MBq • Beta emitters: • < 10 MBqfor beta energy> 0,3 MeV • < 100 MBq for beta energy0,1-0,3 MeV • No workwithopenradiography

  37. SSMFS 2008:28 Restrictions on activity in laboratorywork N.B. Localrestrictionsconcerning max activity at departments Arb I: Risk of inhalation Arb II: Risk of external and internal exposure; small risk of inhalation

  38. SSMFS 2008:28 Documentation/reporting • Data whichshould be documented, signed and keptavailable for concernedpersonnel: • Received and storedradioactivesubstances, and theiractivities • Possession ofcalibrationsources • Results from ventilations and contaminationmonitoring • Results from personneldosemonitoring and estimationsof internal doses

  39. Thankyou for yourpatience www.arbetsmiljo.adm.gu.se www.studentlitteratur.se/#7403-02 (in Swedish) www.stralsakerhetsmyndigheten.se