Ionizing radiation,Ionizing radiation, radiation protectionradiation protection Kateřina BradáčováKateřina Bradáčová Content:Content: types of ionizing radiationtypes of ionizing radiation effects of ionizing radiationeffects of ionizing radiation radiation protectionradiation protection Ionizing radiation:Ionizing radiation: energetic particles or waves that have theenergetic particles or waves that have the potential to ionize an atom or molecule throughpotential to ionize an atom or molecule through atomic interactionsatomic interactions Types of IR:Types of IR: particles currentparticles current ­ (electrons, positrons,­ (electrons, positrons, neutrons, alpha particles, ...)neutrons, alpha particles, ...) gamma raysgamma rays radiationradiation ­ helium nucleus current­ helium nucleus current - high ionizing efficiency- high ionizing efficiency - very short reach- very short reach - in the air ­ 10 cm- in the air ­ 10 cm - in the tissues - 0,03 mm- in the tissues - 0,03 mm Types of IR:Types of IR: radiationradiation ­ electron (­ electron (-) or positron (-) or positron (+)+) currentcurrent - more pentrating than- more pentrating than radiationradiation - longer reach- longer reach ­­ in the tissues ­ a few mmin the tissues ­ a few mm Types of IR:Types of IR: gamma raysgamma rays ­ foton current­ foton current - the highest penetration and reach- the highest penetration and reach Types of IR:Types of IR: radioactive disintegrationradioactive disintegration particle acceleratorsparticle accelerators X-ray apparatusX-ray apparatus Source of IR:Source of IR: alpha disintegrationalpha disintegration ­ strong nuclear repulsion­ strong nuclear repulsion - emitation of alpha particle (helium- emitation of alpha particle (helium nucleus ­ 2 protons and 2 neutrons)nucleus ­ 2 protons and 2 neutrons) - in general:- in general: - e.g.- e.g. Radioactive disintegration:Radioactive disintegration: ( )HeYX A Z A Z 4 2 4 2 + - HeTlBi 4 2 208 81 212 83 + beta- disintegrationbeta- disintegration ­ nucleus which has a lot of­ nucleus which has a lot of neutronsneutrons - in general:- in general: - e.g.- e.g. Radioactive disintegration:Radioactive disintegration: e A Z A Z YX ++ -+ 1 eNC ++ - 14 7 14 6 beta+ disintegrationbeta+ disintegration ­ nucleus which has a lot of­ nucleus which has a lot of protonsprotons - in general:- in general: - e.g.- e.g. Radioactive disintegration:Radioactive disintegration: e A Z A Z YX ++ +- 1 eBC ++ + 11 5 11 6 heavy nucleus disintegrationheavy nucleus disintegration ­ produces two­ produces two daughter nucleuses and severaldaughter nucleuses and several neutronsneutrons - in general:- in general: Radioactive disintegration:Radioactive disintegration: niYYX A Z A Z A Z 1 02 2 21 1 1 ++ linearlinear betatronbetatron (accelerate electrons which strike on the metalic(accelerate electrons which strike on the metalic targettarget X-rays)X-rays) cyclotroncyclotron (to make radionuclides and neutron current)(to make radionuclides and neutron current) Particle accelerators:Particle accelerators: skiagraphyskiagraphy fluoroscopyfluoroscopy skiagraph-fluoroscopyskiagraph-fluoroscopy CTCT angiographyangiography mamographymamography X-ray apparatus:X-ray apparatus: X-ray tubeX-ray tube electrical energy resourceelectrical energy resource examination tableexamination table control panelcontrol panel image amplifierimage amplifier X-ray apparatus:X-ray apparatus: X-ray tube:X-ray tube: - high energy electrons are emited from catode and strike on the- high energy electrons are emited from catode and strike on the metalic anodemetalic anode Bremsstrahlung radiationBremsstrahlung radiation­ electrons are stopped by­ electrons are stopped by repulsive force of electrons in electron shell. Kinetic energyrepulsive force of electrons in electron shell. Kinetic energy of electons is changed into energy of X-ray photonsof electons is changed into energy of X-ray photons Characteristic X-rayCharacteristic X-ray ­ electrons dash out the electrons of K or L­ electrons dash out the electrons of K or L shells. Than the vacant site is filled by electrons from ashells. Than the vacant site is filled by electrons from a higher energy shell.higher energy shell. speed of electronsspeed of electrons - about 165 000 km/s- about 165 000 km/s (voltage 100 kV)(voltage 100 kV) higher voltagehigher voltage higher kinetic energy ofhigher kinetic energy of electronselectrons shorter wave lenghthshorter wave lenghth vawe lenghth ­vawe lenghth ­ 1pm ­ 10nm1pm ­ 10nm X-ray tube:X-ray tube: Filtration and shades:Filtration and shades: FiltrationFiltration ­ reduces intensity of low energy X-ray,­ reduces intensity of low energy X-ray, reduces irradiation of skin and hypodermisreduces irradiation of skin and hypodermis - Al, Cu- Al, Cu - self-filtration, supplementary filtration- self-filtration, supplementary filtration Filtration and shades:Filtration and shades: Secundary (Buckýs) shadeSecundary (Buckýs) shade ­ absorbs secundary­ absorbs secundary and scattered radiationand scattered radiation - from lead belts- from lead belts Effects of ionizingEffects of ionizing radiationradiation Interaction of IR with matter:Interaction of IR with matter: gamma rays ­gamma rays ­ ionize by secondary electrons whichionize by secondary electrons which are caused by this processes:are caused by this processes: Photoelectric effectPhotoelectric effect ­ electrons are emitted from­ electrons are emitted from the atom after the absorption of energythe atom after the absorption of energy from X-rayfrom X-ray Interaction of IR with matter:Interaction of IR with matter: gamma rays ­gamma rays ­ ionize by secondary electrons whichionize by secondary electrons which are caused by this processes:are caused by this processes: Compton effectCompton effect ­ in the electron being given part of­ in the electron being given part of the energy and a photon containing the remainingthe energy and a photon containing the remaining energy being emitted in a different direction fromenergy being emitted in a different direction from the original. If the photon still has enough energy,the original. If the photon still has enough energy, the process may be repeated. If the photon hasthe process may be repeated. If the photon has sufficient energy it can even eject an electron fromsufficient energy it can even eject an electron from its host atom entirely (Photoelectric effect).its host atom entirely (Photoelectric effect). Interaction of IR with matter:Interaction of IR with matter: gamma rays ­gamma rays ­ ionize by secondary electrons whichionize by secondary electrons which are caused by this processes:are caused by this processes: Pair productionPair production - a high-energy photon interacts- a high-energy photon interacts with an atomic nucleus, allowingwith an atomic nucleus, allowing it to produce an electron and ait to produce an electron and a positronpositron Interaction of IR with matter:Interaction of IR with matter: particles current ­particles current ­ the energy of particle is changedthe energy of particle is changed secondary radiationsecondary radiation - primary and secondary radiation ionize atoms- primary and secondary radiation ionize atoms and moleculesand molecules radiationradiation ­ high ionizing efficiency­ high ionizing efficiency - radiation- radiation ­ used in therapy­ used in therapy + radiation+ radiation ­­ used in PETused in PET neutron current ­neutron current ­ used in therapyused in therapy - it is known 4 terms of biological effects of IR- it is known 4 terms of biological effects of IR physical termphysical term ­ takes 10­ takes 10-16-16 -10-10-14-14 ss - energy of photons is handed on electrons,- energy of photons is handed on electrons, it causes ionization and excitation of atomsit causes ionization and excitation of atoms phisiochemical term ­phisiochemical term ­ takes 10takes 10-14-14 -10-10-10-10 ss - interaction of ions with molecules,- interaction of ions with molecules, dissociation of molecules, occurance ofdissociation of molecules, occurance of radicalsradicals Biological effects of IR:Biological effects of IR: - it is known 4 terms of biological effects of IR- it is known 4 terms of biological effects of IR chemical termchemical term ­ takes 0,001 ­ 1 s­ takes 0,001 ­ 1 s - interaction of ions, radicals, excited atoms- interaction of ions, radicals, excited atoms with biological organic molecules (DNA,with biological organic molecules (DNA, proteins)proteins) biological term ­biological term ­ takes a few minutes ­ tens yearstakes a few minutes ­ tens years - functional and morfological changes in- functional and morfological changes in cells, organs and whole organismcells, organs and whole organism Biological effects of IR:Biological effects of IR: DNA damage:DNA damage: -- DNA breakes (singlestrand, doublesrand), interstrandDNA breakes (singlestrand, doublesrand), interstrand cross-linkscross-links cell deathcell death mitoticmitotic ­ cell cannot segment (smaller irradiation)­ cell cannot segment (smaller irradiation) inin interphaseinterphase ­ damage of cell components­ damage of cell components (higher irradiation)(higher irradiation) Cells with high segmentation ability are much more radiosensitive!!!Cells with high segmentation ability are much more radiosensitive!!! mutationmutation ­­ changes in DNA and chromozomeschanges in DNA and chromozomes (gene, chromozomal, somatic X gametic)(gene, chromozomal, somatic X gametic) Cell damage:Cell damage: cellscells - reparation of DNA structure, excision of inreparable- reparation of DNA structure, excision of inreparable DNA segmentsDNA segments tissuestissues -- supplying damaged cells by segmentation ofsupplying damaged cells by segmentation of surviving cellssurviving cells Reparation of:Reparation of: Biological effects of IR:Biological effects of IR: stochasticstochastic - severity is independent of absorbed dose- severity is independent of absorbed dose - threshold does not exist- threshold does not exist - probability of occurrence depends on absorbed dose- probability of occurrence depends on absorbed dose - example: cancer, genetic effect- example: cancer, genetic effect Biological effects of IR:Biological effects of IR: deterministicdeterministic - damage depends on absorbed dose- damage depends on absorbed dose - threshold exists- threshold exists - example: cataract, erythema, infertility etc- example: cataract, erythema, infertility etc accute radiation syndromeaccute radiation syndrome bone marrow formbone marrow form -- threshold 1-2Gy (typical 3-6Gy)threshold 1-2Gy (typical 3-6Gy) - massive loss of leukocytes, greatly increasing the- massive loss of leukocytes, greatly increasing the risk of infectionrisk of infection - uncontrollable bleeding in the mouth, under the- uncontrollable bleeding in the mouth, under the skin and in the kidneysskin and in the kidneys - bone marrow is nearly or completely destroyed, so- bone marrow is nearly or completely destroyed, so a bone marrow transplant is requireda bone marrow transplant is required gastric formgastric form ­­ dose 6-10Gydose 6-10Gy - gastric and intestinal tissue are severely damaged- gastric and intestinal tissue are severely damaged - nausea, vomiting, diarrhoea (loss of minerals and- nausea, vomiting, diarrhoea (loss of minerals and water)water) Deterministic effects:Deterministic effects: accute radiation syndromeaccute radiation syndrome cardiovascularcardiovascular formform -- dose 20Gydose 20Gy - arrythmia, heart failure- arrythmia, heart failure neuropsychic formneuropsychic form -- dose 40Gydose 40Gy -- apatia, letargia, psychic alteration, inactivation ofapatia, letargia, psychic alteration, inactivation of chemical receptors in the brainchemical receptors in the brain infertilityinfertility cataractcataract - dose 4-8 Gy- dose 4-8 Gy acute radiation dermatitisacute radiation dermatitis (erythema, loss of hair all over(erythema, loss of hair all over the body, blisters and ulcers,the body, blisters and ulcers, necrosis)necrosis) Deterministic effects:Deterministic effects: - embryo and foetus are very sensitive to IR- embryo and foetus are very sensitive to IR - damage depends on the dose and the stage of- damage depends on the dose and the stage of developmentdevelopment first 2 weeks ­first 2 weeks ­ ,,all or nothing",,all or nothing" 3.­8. week3.­8. week (organogenesis) ­ risk of malformation(organogenesis) ­ risk of malformation 8.-15. week8.-15. week ­ risk of mental handicap­ risk of mental handicap since 15. weeksince 15. week ­ relative resistance (like a newborn)­ relative resistance (like a newborn) Effects to embryo and foetus:Effects to embryo and foetus: Radiation protectionRadiation protection Dosimetric magnitudes:Dosimetric magnitudes: express quantity of effects of ionizing radiation to matterexpress quantity of effects of ionizing radiation to matter (tissue, patient)(tissue, patient) Dosimetric magnitudesDosimetric magnitudes absorbed doseabsorbed dose ­­ energy which ionizing radiationenergy which ionizing radiation hands on the matter with unit of weighthands on the matter with unit of weight - Gray (Gy)- Gray (Gy) kermakerma ­ energy which primary ionizing radiation­ energy which primary ionizing radiation hands on the matter with unit of weighthands on the matter with unit of weight - Gray (Gy)- Gray (Gy) effective doseeffective dose ­ expresses effects with regard to­ expresses effects with regard to irradiation of various parts of bodyirradiation of various parts of body - Sievert (Sv)- Sievert (Sv) -- gonadsgonads - bone marrow, colon, stomach, lungs- bone marrow, colon, stomach, lungs - breast, urinary bladder, thyroid, liver, oesophagus- breast, urinary bladder, thyroid, liver, oesophagus - skin, bones- skin, bones .. .. .. -- muscles, brainmuscles, brain Radiosensitivity of various types of tissuesRadiosensitivity of various types of tissues and organumand organum Sources of IR:Sources of IR: EUROATOMEUROATOM (law 18/1997)(law 18/1997) - aim of radiation protection- aim of radiation protection (elimination of(elimination of deterministic effects, minimalisation stochasticdeterministic effects, minimalisation stochastic effects)effects) - principle of working with IR (reasons for- principle of working with IR (reasons for working, optimalisation, limitation)working, optimalisation, limitation) public notices of SÚJBpublic notices of SÚJB (184/1997, 146/1997,(184/1997, 146/1997, 214/1997, 307/2002)214/1997, 307/2002) Legislation:Legislation: Limits for workers with IR:Limits for workers with IR: 50 mSv / year50 mSv / year 100 mSv / 5 years100 mSv / 5 years 150 mSv for lens / year150 mSv for lens / year 500 mSv for 1 cm500 mSv for 1 cm22 of skin / yearof skin / year 500 mSv for limbs / year500 mSv for limbs / year Categories of workplaces:Categories of workplaces: 11stst categorycategory ­ small sources, denzitometry, dental­ small sources, denzitometry, dental X-rayX-ray 22ndnd categorycategory ­ radiodiagnostics, therapy­ radiodiagnostics, therapy 33rdrd categorycategory ­ particle accelerators­ particle accelerators 44thth categorycategory ­ nuclear power station, disposal site­ nuclear power station, disposal site of nuslear wasteof nuslear waste physicalphysical timetime -- work as quickly as possiblework as quickly as possible distancedistance ­ by doubling the distance the dose rate is­ by doubling the distance the dose rate is quarteredquartered shieldingshielding -- radiation - clothes, paper, plexiglassradiation - clothes, paper, plexiglass radiation ­ plexiglass or aluminumradiation ­ plexiglass or aluminum rays ­ lead, steel, baryum concreterays ­ lead, steel, baryum concrete neutron radiation ­ materials containing a lotneutron radiation ­ materials containing a lot of hydrogen, cadmium and boronof hydrogen, cadmium and boron chemicalchemical -- radioprotective substancesradioprotective substances biologicalbiological ­­ improving the immunityimproving the immunity Radiation protection:Radiation protection: Protection of workers with IR:Protection of workers with IR: personal dosimetrypersonal dosimetry -- measure an absolute dose received over a period ofmeasure an absolute dose received over a period of timetime - by personal dosimetres- by personal dosimetres dozimetresdozimetres: film, termoluminescent,: film, termoluminescent, scintilation, electrical,scintilation, electrical, chemicalchemical Principle 1: reasons of medical irradiationPrinciple 1: reasons of medical irradiation - risk of the radiation damage must be less than a- risk of the radiation damage must be less than a benefit for the patientbenefit for the patient Principle 2: optimalizationPrinciple 2: optimalization - it is needed to aplicate the minimal necessary- it is needed to aplicate the minimal necessary quantity of radiation which guarantees thequantity of radiation which guarantees the quality of radiogramquality of radiogram Protection of patients:Protection of patients: Was the examination done?Was the examination done? Do you necessary need this examinaton?Do you necessary need this examinaton? Do you need the examination now?Do you need the examination now? Is it the best type of examination?Is it the best type of examination? Protection of patients:Protection of patients: Effective doses of X-ray examinations:Effective doses of X-ray examinations: 4 years10CT of abdomen or pelvis 3,2 years8CT of chest 11 months2,3CT of head 2,8 years7irrigoscopy 1,2 years3Fluoroscopy of colon 1,2 years3Fluoroscopy of stomach 1 year2,5urography 1,5 days0,01R. of limb 1,5 months0,3R. of hip joint 3,5 months0,7R. of pelvis 5 months1R. of abdomen 3 days0,02R. of chest 6 months1,3R. of L spine 3,5 months0,7R. of Th spine 10 days0,07Radiogram of skull Time to stay in natural background radiation Typical effective dose (mSv) Type of examination Effective doses of examination in NM:Effective doses of examination in NM: 3 years7,5Scintigraphy of myocardium 10,5 months2,2Scintigraphy of thyroid 6 months1,2Perfused scintigraphy of lungs 16 months3,4Scintigraphy of skeleton 11 months2,3Dynamic cholescintigraphy 10,5 months2,2Dynamic scintigraphy of kidneys 7 months1,5Static scitigraphy of kidneys Time to stay in natural background radiation Typical effective dose (mSv) Type of examination