Overview of Radiation Protection - PowerPoint Presentation

1. Overview of Radiation ProtectionBálint Vecsei dr.Principles of radiation protection, dose limits

2. http://www.kernenergie.de

3. radioaktivität röntgenstrahlen und gesundheit

4. Radiation is indispensable in modern medicineThe radiographic examination is one of the principal diagnostic method used in all fields of medical servicesThe risk associated with low-level diagnostic exposures could be low, but greater than zeroFor this reason it is required to measure the dose in the diagnostic radiologyIntroduction

5. IntroductionRadiographic examinations play an essential part of dental practice.The use of X-rays is an integral part of clinical dentistryOn the majority of patients some form of radiographic examination is necessary„The clinican’s main diagnostic aid.”The range of knowledge of dental radiography can be divided conveniently into four main sections:Basic physics and equipmentRadiaton protectionRadiographyRadiology

6. Every day all over the world people are exposed to ionising radiation, almost all from natural sources in the environment or for medical reasons. Ionising radiation has enough energy to cause damage cells which can increase the risk of cancer later in life. In general the health effects of ionising radiation are dependent on the received dose.Several different terms and units have been used in dosimetry over the years. Natural sources account most of the radiation we all receive each year

7. A banana equivalent dose (abbreviated BED) is an informal expression of ionising radiation exposure, intended as a general educational example to indicate the potential dose due to naturally occurring radioactive isotopes by eating one average sized banana. However, in practice this dose is not cumulative as the principal radioactive component is excreted to maintain metabolic equilibrium. The BED is only an indicative concept meant to show the existence of very low levels of natural radioactivity within a natural food, and is not a formally adopted dose quantity.The concept probably originated on the RadSafe nuclear safety mailing list in 1995,[original research?] where a value of 9.82×10−8 sieverts or about 0.1 μSv was suggested for a 150 gram banana.A banana equivalent dose (abbreviated BED) is an informal expression of ionising radiation exposure, intended as a general educational example to indicate the potential dose due to naturally occurring radioactive isotopes by eating one average sized banana. However, in practice this dose is not cumulative as the principal radioactive component is excreted to maintain metabolic equilibrium. The BED is only an indicative concept meant to show the existence of very low levels of natural radioactivity within a natural food, and is not a formally adopted dose quantity.

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9. Comparison of doses from sources of exposureSource of ExposureDoseDental X-ray0.005 mSv135g bag of Brazil nuts0.005 mSv Chest X-ray0.02 mSvTransatlantic flight0.07 mSvNuclear power station worker average annual occupational exposure0.18 mSvUK annual average radon dose1.3 mSvCT scan of the head1.4 mSvUK average annual radiation dose2.7 mSvUSA average annual radiation dose6.2 mSvCT scan of the chest6.6 mSvAverage annual radon dose to people in Cornwall7.8 mSvWhole body CT scan10 mSvAnnual exposure limit for nuclear industry employees20 mSvLevel at which changes in blood cells can be readily observed100 mSvAcute radiation effects including nausea and a reduction in white blood cell count1000 mSvDose of radiation which would kill about half of those receiving it in a month5000 mSv

10. Units of radiation and radioactivityIn order to quantify how much radiation we are exposed to in our daily lives and assess potential health impacts as a result, it is necessary to establish a unit of measurement.The basic unit of radiation dose absorbed in tissue is the gray (Gy), where one gray represents the deposition of one joule of energy per kilogram of tissue.However, since neutrons and alpha particles cause more damage per gray than gamma or beta radiation, another unit, the sievert (Sv) is used in setting radiological protection standards. This unit of measurement takes into account biological effects of different types of radiation.One gray of beta or gamma radiation has one sievert of biological effect, one gray of alpha particles has 20 Sv effect and one gray of neutrons is equivalent to around 10 Sv (depending on their energy).Since the sievert is a relatively large value, dose to humans is normally measured in millisieverts (mSv), onethousandth of a sievert.

11. Everyone is exposed to some form of ionizing radiation from the environment in which we live.Natural background radiationCosmic radiation from the earth's atmosphereGamma radiation from the rocks and soil in the earth's crustRadiation from ingested radioisotopes, e.g. 40K, in certain foodsRadon and its decay products, 222Rn is a gaseous decay product of uranium that is present naturally in granite. As a gas, radon diffuses readily from rocks through soil and can be trapped in poorly ventilated houses and then breathed into the lungsArtificial background radiationFallout from nuclear explosionsRadioactive waste discharged from nuclear establishmentsMedical and dental diagnostic radiationRadiation from occupational exposure.

12. Diagnostic radiology represents the largest source of artificial radiation which is comparable to natural background exposureRecently, patient exposure to medical and dental X-ray examination has grown rapidlyEstimated annual doses from various sources of radiation: 2,4-3,4 mSv/year

13. Radiologic and Nuclear Medicine Studies in the United States and Worldwide: Frequency, Radiation Dose, and Comparison with Other Radiation Sources—1950–2007Global annual per-capita effective radiation dose from various sources for (a) 1980 –1984 (11) and (b) 1997–2007 (15). Bkdbackground.Radiology: Volume 253: Number 2—November 2009 ▪ radiology.rsna.org

14. U.S. annual per-capita effective radiation dose from various sources for (a) 1980 and (b) 2006 by using UNSCEAR value of 2.4 mSv for natural background(Bkd) (for a, NCRP 1987 estimated value, 3.0 mSv; for b, NCRP 2009 estimated value, 3.1 mSv).Radiology: Volume 253: Number 2—November 2009 ▪ radiology.rsna.org

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17. Egyes repülési útvonalakon adódó sugárterhelésekkülönböző légitársaságok mérései alapjánÚtvonalTeljes effektív dózis (μSv)Zágráb - Ontarió35,1New York - Florida18,9Buenos Aires - Újzéland57,2Amsterdam - Tokió55,6Amsterdam - Milánó4,8Helsinki - New York34,8Koppenhága - Bangkok 23,0Koppenhága - Stockholm2,2Brüsszel - Johannesburg28,4Brüsszel - Tokió83,0Frankfurt - Brakheim13,5Frankfurt - New York30,3Frankfurt - Chicago40,4Budapest - New York62,9Budapest - Beijing56,4Budapest - Bangkok37,9X 15 = 0,9435 mSv

18. The risk associated with diagnostic exposures greater than zeroFor this reason it is prerequisite to measure the dose to the patients in the diagnostic radiology precisely.The radiation dose to the patients should be as low as reasonably achievable, a principle known as ALARA (International Commission on Radiological Protection)The number of diagnostic examinations should also be taken into consideration because the risk is directly proportional to the frequency of X-ray exposure.

19. How can you reduce external radiation exposure?  Time: It’s important to minimize your time of radiation exposure.Distance: Doubling the distance between your body and the radiation source will divide the radiation shielding exposure by a factor of 4.Shielding: Using absorber materials such as lead for X-rays and gamma rays is an effective way to reduce radiation exposures.

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21. Dental radiographic examinations are one of the most frequently performed radiological studies.The effective dose delivered to patients per radiograph is low but the collective dose is significant because of the large number of radiographs made.

22. Effects of radiation are grouped into two categoriesDeterministic-effects are based on cell killing and are characterized by a threshold dose. Below the threshold dose there is no clinical effect. With exposures above the threshold dose the severity of the injury increases with dose.Stochastic-effects, including cancer and heritable effects are based on damage to DNA. There is no-threshold or ‘‘safe’’ dose.

23. Persons are medically exposed as part of their diagnostic or treatmentAccording to ICRP and BSS, two basic principles of radiation protection are to be complied with: justification and optimizationDose limits are not applicable, but a guidance is given on dose levelsInvestigation of exposures is strongly recommended

24. Three types of exposureMedical Exposure (principally the exposure of persons as part of their diagnostic or treatment)Occupational Exposure (exposure incurred at work, and practically as a result of work)Public Exposure (including all other exposures)

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26. !!!!!! Medical exposure!!! Public exposure! Occupatianal exposure

27. The aim of radiation protection in dentistry is to obtain the desired clinical information with minimum radiation exposure to patients, dental personnel, and the public.

28. Workload?The aim of radiation protection in dentistry is to obtain the desired clinical information with minimum radiation exposure to patients, dental personnel, and the public.

29. Framework of radiological protection for medical exposureJustificationNo practice should be adopted unless its introduction produces a positive net benefit.OptimizationAll exposures should be kept as low as reasonably achievable, economic and social factors being taken into account.The use of doses limits The exposure of individuals should not exceed the limits recommended for the appropriate circumstances.Dose constraints and guidance (or reference) levels ARE RECOMMENDED

30. Three levels of justificationGeneral level: The use of radiation in medicine is accepted as doing more good than harmGeneric level:Specific procedure with a specific objective (eg. chest radiographs for patients showing relevant symptoms)Third level:The application of the procedure to an individual patient

31. Generic justification (I)It is a matter for national professional bodies, sometimes in conjunction with national regulatory authoritiesThe exposures to staff (occupational) and to members of the public should be taken into accountThe possibility of accidental or unintended exposures (potential exposure) should also be consideredThe decisions should be reviewed from time to time as new information becomes available

32. Justification for an individual patient (third level)To check that the required information is not yet availableOnce the procedure is generically justified, no additional justification is needed for simple diagnostic investigationsFor complex procedures (such as CT, IR, etc) an individual justification should be taken into account by medical practitioner (radiologist, referral doctor..)

33. The optimization of protectionOptimization is usually applied at two levels:The design and construction of equipment and installationsDay to day radiological practice (procedures)Reducing the patient dose may reduce the quantity as well as the quality of the information provided by the examination or may require important extra resourcesThe optimization means that doses should be “as low as reasonably achievable, economic and social factors being taken into account” compatible with achieving the required objective

34. Risk and Dosislevels

35. Risk of different activities (not ordered)AtomenergySmokingAntibioticsX-ray diagnosticElectrocityCyclingFood preservationAutomobileConsumtion of alcoholic drinks

36. Risk of different activities (increasing risk)SmokingConsumtion of alcoholic drinksAutomobileElectrocityX-ray diagnosticCyclingAtomenergyFood preservationAntibiotics

37. 1 micro-risk2500 km travel by train2000 km flight80 km by bus65 km by car12 km by bike3 km by motor bikesmoke of one cigarette2 month living together with a smokereat one more bread and butter for a fat manbreath 1 hour in Budapestsleep in a house one weekto be stroked by thunder in 10 years

38. BenifitBenifit and risk

39. BenifitRiskBenifit and risk

40. Overview of dose quantitiesPhysicaleffectChemicaleffectBio-chemicaleffectBiologicaleffectRadiationAbsorbed dosisEquivalent doseEffective doseRISKReflects the combined detriment from stochastic effects due to the equivalent doses in all the organs and tissues of the bodyThe combination of probability and severity of harm is called “detriment”.

41. Estimated lifetime risk as a function of age

42. We live with1-3 mSvCan kill4000 mSvRadiationWhere to stop, where is the safe point?What are the effects of radiation?

43. Changes in Dose Limit (ICRP)mSvYear

44. Dose constraints for medical exposureFor medical exposure dose constraints should only be used in optimizing the protection of persons exposed for medical research purposes, or of persons, other than workers, who assist in the care, support or comfort of exposed patients.44

45. Dose constraintsfor medical research purposesfor individuals helping in care, support or comfort of patients, and visitors5 mSv during the period of the examination or treatment1 mSv for children visiting45

46. PUBLIC - Optimization under ConstraintsDOSE LIMITSeffective dose of 1 mSv in a yearin special circumstances, effective dose of 5 mSv in a single year, provided that the average over five consecutive years in less than 1mSv per yearequivalent dose to lens of the eye 15 mSv in a yearequivalent dose to skin of 50 mSv in a year.46

47. Occupational dose limits 100 mSv/5 years effective doseBUT does not allowed over 50 mSv in any year!

48. Occupational PublicEffective dose 20 mSv/yr averaged * 1 mSv in a yr over 5 yrs.Annual equivalentdose toLens of eye 20 mSv 15 mSvSkin 500 mSv 50 mSvHands & Feet 500 mSvN.B.: M.P.D. 1931 = 500 mSv, 1947=150 mSv, 1977=50 mSv & in 1990=20 mSvDose Limits (ICRP 60)

49. Students, trainee Effective dose 6 mSv/yr Annual equivalentdose toLens of eye 15 mSv Skin 150 mSv Hands & Feet 150 mSvN.B.: M.P.D. 1931 = 500 mSv, 1947=150 mSv, 1977=50 mSv & in 1990=20 mSvDose Limits (ICRP 60)

50. Personal DosimetryPersonal dosimetry provides the means to measure and record radiation doses received by individual workers.Personal dosemeters should be worn by operators who take more than 100 intra-oral films or 50 panoramic films per week.In practice, the majority of dentists and support staff do not need to wear dosemeters although many do so as a reassurance measure.

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52. Qualitative risk levelsNegligible risk: less than 2 days of natural background exposureMinimal risk: more than 2 days and up to 1 month of natural background exposureVery low risk: more than 1 month and up to 8 months of natural background exposureLow risk: more than 8 months and up to 6 years of natural background exposureModerate risk: more than 6 years of natural background exposure

53. Thank you for your attention!