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Ionizing radiation hazards and safety :must know


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Ionizing radiation hazards and safety :must know

  1. 1. Ionizing radiation...Effects and Safety what every physician must know Dr/Ahmed bahnassy Consultant radiologist PSMMC
  2. 2. Aims of lecture • To become familiar with the mechanisms & biological effects following exposure to ionizing radiation. • To be aware of the risks of ionizing radiation . • To know main safety issues of protection.
  3. 3. RADIATION:- Radiation is the energy that comes from a source and travels through some material or space as waves or photons. IONIZING RATIATION:- This kind of radiation on interaction with matter produce charged particles called ions. This type of radiation has enough energy to break chemical bonds. NON-IONIZING RATIATION:- Radiation that does not have enough energy to break chemical bonds but can vibrate atom. It cannot produce ions.
  5. 5. UNITS OF RADIATION:- 1) Roentgen (R):- Radiaton exposure in a volume of air. 2) Rad:- It is the unit of absorbed dose. The SI unit of absorbed dose is Gray (Gy) 1 Gy=100 rad 3) Rem:- It is the unit of effective dose. Used only in radiation protection. The SI unit is Sievert 1 Sv= 100 rem 1 mSv = 0.001 Sv.
  6. 6. 0.01 mSv 0.5 Chest X-ray. 0.02mSv 1 CXR 0.07 mSv 3.5 CXR 1.3mSv 65 CXR 0.7mSv 1.0mSv 2.5mSv 3.0mSv 7.0mSv 35 CXR 50 CXR 125CXR 150CXR 350CXR
  7. 7. 2.3mSv 8.0mSv 10mSv 115 Chest 400 CXR 500 CXR X-rays.
  8. 8. 15 mSv 750 CXR 4 mSv 200 CXR 6 mSv 300 CXR
  9. 9. THYROID SCAN RENAL SCAN LUNG PERFUSION 1.0 mSv 1.0 mSv 1.0 mSv 50 CXR 50 CXR 50 CXR BONE SCAN PET HEAD (FDG) CARDIAC GATED 4.0 mSv 5.0 mSv 6.0 mSv 200 CXR 250 CXR 300 CXR
  10. 10. IIoonniizziinngg RRaaddiiaattiioonn....HHooww eeffffeeccttss aarree pprroodduucceedd IIoonniizziinngg RRaaddiiaattiioonn iiss tthhee rreemmoovvaall ooff aann eelleeccttrroonn ffrroomm aann aattoomm lleeaavviinngg aann uunnssttaabbllee mmoolleeccuullee wwhhiicchh mmaayy tthheenn bbrreeaakk aappaarrtt ttoo ffoorrmm ffrreeee rraaddiiccaallss.. The weapon
  11. 11. LLiinneeaarr EEnneerrggyy TTrraannssffeerr ((LLEETT)) TThhee aavveerraaggee eenneerrggyy ddeeppoossiitteedd ppeerr uunniitt lleennggtthh ooff ttrraacckk.. MMeeaassuurreedd iinn kkiillooeelleeccttrroonn vvoollttss ppeerr mmiiccrroonn ((1100--66 mm))
  12. 12. LLooww LLEETT // HHiigghh LLEETT  LLooww LLEETT LLooww mmaassss,, iinnccrreeaasseedd ttrraavveell ddiissttaannccee ((ggaammmmaa rraayyss,, xx-- rraayyss)).. SSppaarrsseellyy iioonniizziinngg wwiitthh rraannddoomm iinntteerraaccttiioonnss.. CCaauusseess ddaammaaggee pprriimmaarriillyy tthhrroouugghh iinnddiirreecctt aaccttiioonn oorr mmaayy ccaauussee ssiinnggllee ssttrraanndd bbrreeaakkss ((wwhhiicchh aarree rreeppaaiirraabbllee)).. e-
  13. 13. LLooww LLEETT // HHiigghh LLEETT HHiigghh LLEETT – LLaarrggee mmaassss,, ddeeccrreeaasseedd ttrraavveell ddiissttaannccee ((aallpphhaa ppaarrttiicclleess,, pprroottoonnss,, llooww eenneerrggyy nneeuuttrroonnss)).. – CCaauusseess ddeennssee iioonniizzaattiioonn aalloonngg iittss ppaatthh wwiitthh aa hhiigghh pprroobbaabbiilliittyy ooff iinntteerraaccttiinngg ddiirreeccttllyy wwiitthh DDNNAA.. α++
  14. 14. IIoonniizziinngg RRaaddiiaattiioonn The injury mechanism TThhee rreeaaccttiioonnss ccaauusseedd bbyy iioonniizziinngg rraaddiiaattiioonn ooccccuurr rraappiiddllyy,, tthheeyy aarree nnoonnsseelleeccttiivvee aanndd rraannddoomm.. TThhee mmaajjoorriittyy ooff ddaammaaggee ccaauusseedd bbyy rraaddiiaattiioonn iiss dduuee ttoo cchheemmiiccaall rreeaaccttiioonnss wwiitthh wwaatteerr wwiitthhiinn tthhee cceellll..
  15. 15. H2O HOH+ H+ OH* Positively charged water molecule H* OH - e- + H2O HOH-water negatively charged water molecule Hydrogen ion Hydroxyl electron radical water hydrogen radical Hydroxyl ion The negatively charged water molecule dissociates into a hydrogen radical and a hydroxyl ion.
  16. 16. RReeaaccttiioonnss TThhee pprreevviioouuss rreeaaccttiioonnss pprroodduuccee ffrreeee eelleeccttrroonnss ((ee--)),, tthhee iioonnss HH-- aanndd OOHH--,, tthhee ffrreeee rraaddiiccaallss HH** aanndd OOHH**.. TThhee ffaattee ooff tthheessee pprroodduuccttss aarree…………..
  17. 17. FFrreeee RRaaddiiccaallss AA ffrreeee rraaddiiccaall iiss aann aattoomm oorr mmoolleeccuullee tthhaatt hhaass aann uunnppaaiirreedd eelleeccttrroonn iinn iittss vvaalleennccee sshheellll.. TThheessee ffrreeee rraaddiiccaallss aarree nnoonn--sseelleeccttiivvee wwhheenn ppaaiirriinngg uupp wwiitthh eelleeccttrroonnss ffrroomm ootthheerr aattoommss,, iinncclluuddiinngg tthhoossee tthhaatt mmaakkee uupp tthhee DDNNAA mmoolleeccuullee..
  18. 18. DDiirreecctt AAccttiioonn // IInnddiirreecctt AAccttiioonn DDiirreecctt AAccttiioonn CCaauusseess ddaammaaggee ddiirreeccttllyy ttoo DDNNAA oorr ootthheerr iimmppoorrttaanntt mmoolleeccuulleess iinn tthhee cceellll.. MMoorree lliikkeellyy wwhheenn tthhee bbeeaamm ooff cchhaarrggeedd ppaarrttiicclleess ccoonnssiisstt ooff aallpphhaa ppaarrttiicclleess,, pprroottoonnss,, oorr eelleeccttrroonnss IInnddiirreecctt AAccttiioonn CCaauusseess ddaammaaggee bbyy iinntteerraaccttiinngg wwiitthh tthhee cceelllluullaarr mmeeddiiuumm pprroodduucciinngg ffrreeee rraaddiiccaallss wwhhiicchh tthheenn ddaammaaggee tthhee DDNNAA mmoolleeccuullee.. MMoorree lliikkeellyy wwhheenn xx--rraayyss oorr ggaammmmaa--rraayyss ccoommppoossee tthhee bbeeaamm..
  19. 19. DDiirreecctt AAccttiioonn // IInnddiirreecctt AAccttiioonn
  20. 20. DDNNAA DDaammaaggee  TThhee aarrrraannggeemmeenntt ooff nniittrrooggeennoouuss bbaasseess pprroovviiddee aa bblluueepprriinntt ffoorr DDNNAA ffoorr tthhee ssyynntthheessiiss ooff ssppeecciiffiicc pprrootteeiinnss nneecceessssaarryy ffoorr iinnddiivviidduuaall cceellll ffuunnccttiioonn..  IInn tthhee eevveenntt ooff aa lloossss oorr cchhaannggee ooff oonnee oorr mmoorree ooff tthhee nniittrrooggeennoouuss bbaasseess........bbaassee sseeqquueennccee aanndd nnoorrmmaall ffuunnccttiioonniinngg ooff tthhee cceellll iiss aalltteerreedd..  AAnnootthheerr ffoorrmm ooff DDNNAA ddaammaaggee dduuee ttoo rraaddiiaattiioonn iinnvvoollvveess aa bbrreeaakk iinn tthhee hhyyddrrooggeenn bboonnddss bbeettwweeeenn tthhee AAddeenniinnee –– TThhyymmiinnee aanndd CCyyttoossiinnee –– GGuuaanniinnee bbaassee ppaaiirrss.. TThheessee bboonnddss ffuunnccttiioonn ttoo kkeeeepp tthhee DDNNAA ssttrraannddss ttooggeetthheerr  BBoonnddss ccaann aallssoo bbrreeaakk bbeettwweeeenn ddeeooxxyyrriibboossee ssuuggaarr aanndd tthhee pphhoosspphhaattee ggrroouuppss wwhhiicchh ccaann lleeaadd ttoo ccrroossss--lliinnkkiinngg ooff DDNNAA The target
  21. 21. CChhrroommoossoommee AAbbeerrrraattiioonnss  IIff tthhee cchhrroommoossoommee ffrraaggmmeennttss aarree nneeaarr oonnee aannootthheerr tthheeyy hhaavvee aa hhiigghh cchhaannccee ooff rreeaattttaacchhiinngg iinn tthheeiirr oorriiggiinnaall ppoossiittiioonn –– ccaauussiinngg nnoo ffuuttuurree ddaammaaggee ttoo tthhee cceellll..AA pprroocceessss kknnoowwnn aass rreessttiittuuttiioonn..  IInn ttrraannssllooccaattiioonnss aanndd iinnvveerrssiioonnss,, nnoo ggeenneettiicc iinnffoorrmmaattiioonn iiss lloosstt,, bbuutt tthhee rreeaarrrraannggeemmeenntt ooff ggeennee sseeqquueennccee wwiillll aalltteerr pprrootteeiinn ssyynntthheessiiss..  IInn aa ddeelleettiioonn,, aa cchhrroommoossoommee ffrraaggmmeenntt iiss nnoott rreepplliiccaatteedd dduurriinngg tthhee nneexxtt mmiittoossiiss,, tthhee ggeenneettiicc iinnffoorrmmaattiioonn iiss lloosstt.. TThhee eeffffeeccttss tthhiiss hhaass oonn tthhee cceellll ddeeppeennddss oonn tthhee aammoouunntt aanndd ttyyppee ooff iinnffoorrmmaattiioonn lloosstt.. The effects Inversion Translocation Deletion
  22. 22. Chromosome deletion Chromosome translocation
  23. 23. Outcomes after cell exposure DAMAGE REPAIRED DAMAGE TO DNA CELL DEATH (APOPTOSIS) TRANSFORMED CELL IAEA 3 : Biological effects of ionizing radiation
  24. 24. DNA Mutation Mutation repaired Cell survives but mutated Viable Cell Cancer ? Cell death Unviable Cell
  25. 25. Repair of DNA damage • RADIOBIOLOGISTS ASSUME THAT THE REPAIR SYSTEM IS NOT 100% EFFECTIVE. IAEA 3 : Biological effects of ionizing radiation
  26. 26. CCaanncceerr iinniittiiaattiioonn
  28. 28. CELL INITIATION An initiating event creates a mutation in one of the basal cells
  29. 29. DYSPLASIA More mutations occurred. The initiated cell has gained proliferative advantages. Rapidly dividing cells begin to accumulate within the epithelium.
  30. 30. BENIGN TUMOR More changes within the proliferative cell line lead to full tumor development.
  31. 31. MALIGNANT TUMOR The tumor breaks trough the basal lamina. The cells are irregularly shaped and the cell line is immortal. They have an increased mobility and invasiveness.
  32. 32. METASTASIS Cancer cells break through the wall of a lymphatic vessel or blood capillary. They can now migrate throughout the body and potentially seed new tumors.
  33. 33. A simple generalized scheme for multistage oncogenesis Damage to chromosomal DNA of a normal target cell Failure to correct DNA repair Appearance of specific neoplasia-initiating mutation Promotional growth of pre-neoplasm Conversion to overtly malignant phenotype Malignant progression and tumour spread
  34. 34. RRaaddiioosseennssiittiivviittyy AAccttiivveellyy rreepprroodduucciinngg cceellllss aarree mmoorree rraaddiioosseennssiittiivvee tthhaann mmaattuurree cceellllss.. DDuurriinngg mmiittoossiiss,, tthhee cceellll iiss iinn aa ssttrreesssseedd ssttaattee aanndd sshhoowwss aann iinnccrreeaassee iinn ddaammaaggee ccaauusseedd bbyy rraaddiiaattiioonn.. CCeellllss tthhaatt hhaavvee ddeeccrreeaasseedd lleevveellss ooff ddiiffffeerreennttiiaattiioonn aarree mmoorree rraaddiioosseennssiittiivvee tthhaann ssppeecciiaalliizzeedd cceellllss..
  35. 35. The Cell Cycle  An ordered set of events, culminating in cell growth and division into two daughter cells  Tc, full mitotic cycle G2 (2nd gap) M (mitosis) S (DNA Synthesis phase) G1 (1st gap) Cells that cease division
  36. 36. Radiosensitivity & Mitotic Cycle  Cell cycle components  M, G1, S, G2  Cell cycles times vary largely due to G1  crypt cells, 9 - 10 hours  stem cells (mouse skin) 200 hr  Sensitivity  Cells most sensitive close to mitosis  Resistance greatest in latter part of S  For long G1’s, there is an early resistance period followed by sensitive one at the end of G1  G2 ~ M in sensitivity
  37. 37. Radiosensitivity High RS Medium RS Low RS Muscle Bones Nervous system Skin Mesoderm organs (liver, heart, lungs…) Bone Marrow Spleen Thymus Lymphatic nodes Gonads Eye lens Lymphocytes (exception to the RS laws) IAEA 3 : Biological effects of ionizing radiation
  38. 38. FFrraaccttiioonnaattiioonn iinn rraaddiiootthheerraappyy  IInnsstteeaadd ooff aa ssiinnggllee ttrreeaattmmeenntt ccoonnssiissttiinngg ooff aa hhiigghh ddoossee,, ffrraaccttiioonnaattiioonn ddiivviiddeess tthhee ddoossee ttoo bbee ddeelliivveerreedd oovveerr aa ppeerriioodd ooff ttiimmee,, uussuuaallllyy 66--88 wweeeekkss..  AAtt llooww ddoosseess ooff rraaddiiaattiioonn,, nnoorrmmaall cceellllss hhaavvee aann iinnccrreeaasseedd ssuurrvviivvaall rraattee bbeeccaauussee ooff tthheeiirr aabbiilliittyy ttoo rreeppaaiirr ssuubblleetthhaall ddaammaaggee bbeeffoorree tthhee nneexxtt ffrraaccttiioonn ooff rraaddiiaattiioonn iiss ddeelliivveerreedd..  TTuummoorr cceellllss ddoo nnoott ppoosssseessss tthhee rreeppaaiirr eennzzyymmeess nneecceessssaarryy ttoo kkeeeepp uupp wwiitthh tthhee rreeppaaiirrss aanndd aass aa rreessuulltt tthhee cceellll iiss oovveerrwwhheellmmeedd aanndd iiss ddeessttrrooyyeedd..
  39. 39. Dose-Response Relationships  Two effects of radiation exposure:  deterministic (threshold)  stochastic: cancer  Radiation Standards  set below threshold  set to limit stochastic risk
  40. 40. Non-Stochastic (Deterministic) Effects  Occurs above threshold dose  Severity increases with dose  Alopecia (hair loss)  Cataracts  Erythema (skin reddening)  Radiation Sickness  Temporary Sterility
  41. 41. Stochastic (Probabilistic) Effects  Occurs by chance  Probability increases with dose  Carcinogenesis  Mutagenesis  Teratogenesis
  42. 42. Radiation health effects CELL DEATH DETERMINISTIC Somatic Clinically attributable in the exposed individual STOCHASTIC somatic & hereditary epidemiologically attributable in large populations ANTENATAL somatic and hereditary expressed in the foetus, in the live born or descendants IAEA 3 : Biological effects of ionizing radiation BOTH TYPE OF EFFECTS CELL TRANSFORMATION
  43. 43. Radiation effects and Syndromes
  44. 44. Injury Threshold Dose to Skin (Sv) Weeks to Onset Early transient erythema 2 <<1 Temporary epilation 3 3 Main erythema 6 1.5 Permanent epilation 7 3 Dry desquamation 10 4 Invasive fibrosis 10 Dermal atrophy 11 >14 Telangiectasis 12 >52 Moist desquamation 15 4 Late erythema 15 6-10 Dermal necrosis 18 >10 Secondary ulceration 20 >6 IAEA 3 : Biological effects of ionizing radiation Skin damage from prolonged fluoroscopic exposure Skin reactions
  45. 45. Skin injuries IAEA 3 : Biological effects of ionizing radiation
  46. 46. Effects in eye • Eye lens is highly RS. • Coagulation of proteins occur with doses greater than 2 Gy. • There are 2 basic effects: Histologic view of eye: From “Atlas de Histologia...”. J. Boya Detectable 0.5-2.0 > 0.1 opacities Eye lens is highly RS, moreover, it is surrounded by highly RS cuboid cells. 5.0 > 0.15 Visual impairment (cataract) IAEA 3 : Biological effects of ionizing radiation Sv/year for many years Sv single brief exposure Effect
  47. 47. Whole body response: adult Acute irradiation syndrome Chronic irradiation syndrome Steps: 1. Prodromic (onset of disease) 2. Latency 3. Manifestation Lethal dose 50 / 30 IAEA 3 : Biological effects of ionizing radiation 49 Survival time Dose BONE MARROW GASTRO INTESTINA L CNS (central nervous system) 1-10 Gy 10 - 50 Gy > 50 Gy •Mechanism: Neurovegetative disorder •Similar to a sick feeling •Quite frequent in fractionated radiotherapy
  48. 48. Threshold Doses for Deterministic Effects • Cataracts of the lens of the eye 2-10 Gy • Permanent sterility • males 3.5-6 Gy • females 2.5-6 Gy • Temporary sterility • males 0.15 Gy • females 0.6 Gy Severity of effect dose threshold
  49. 49. Symptoms of Acute Radiation Sickness  Three categories (E. Hall, 1994)  Hemopoietic: 3-8 Gy LD50/60  radiation damages precursors to red/white blood cells & platelets  prodromal may occur immediately  symptoms: septicemia,  survival mixed  examples include Chernobyl personnel (203 exhibited symptoms, 13 died)
  50. 50. Symptoms, continued  Gastrointestinal : >10 Gy  radiation depopulates GI epithelium (crypt cells)  abdominal pain/fever, diarrhea, dehydration  death 3 to 10 days (no record of human survivors above 10 Gy)  examples include Chernobyl firefighters  Cerebrovascular : > 100 Gy  death in minutes to hours
  51. 51. Delayed Effects  SOMATIC: they affect the health of the irradiated person. They are mainly different kinds of cancer (leukemia is the most common, with a delay period of 2-5 years, but also colon, lung, stomach cancer…)  GENETIC: they affect the health of the offspring of the irradiated person. They are mutations that cause malformation of any kind (such as mongolism)
  52. 52. RADIATION PROTECTION Based on two components. A) JUSTIFICATION. B) OPTIMIZATION. JUSTIFICATION:- Applications of ionising radiation are only justified when they provide a net benefit with minimization of risks of radiation for people.
  53. 53. GUIDELINES FOR REFERRING PHYSICIANS:- 1) Repeating investigations which have already been done: For example at other hospital, in an outpatient department, or in an accident and emergency department. HAS IT BEEN DONE ALREADY? Every attempt should be made to get previous films. 2) Investigation when results are unlikely to affect patient management: The anticipated 'positive' finding is usually irrelevant, e.g. degenerative spinal disease (as 'normal' as white hairs in old age) or because a positive finding is so unlikely. DO I NEED IT?
  54. 54. 3) Investigating too often:- i.e. before the disease could have progressed or resolved or before the results could influence treatment. DO I NEED IT NOW? Or some clinicians tend to rely on investigations more than others. ARE TOO MANY INVESTIGATIONS BEING PERFORMED? 4) Doing the wrong investigation:- Imaging techniques are developing rapidly. It is often helpful to discuss an investigation with a specialist in clinical radiology or nuclear medicine before it is requested. IS THIS THE BEST INVESTIGATION? 5) Failing to provide appropriate clinical information & questions that imaging Investigation should answer. Deficiencies here may lead to the wrong technique being used (e.g. the omission of an essential view). HAVE I EXPLAINED THE PROBLEM?
  55. 55. OPTIMIZATION:- Once a practice is justified, the exposure to ionising radiation should be kept as low as reasonably achievable (ALARA).
  56. 56. FUNDAMENTAL PRINCIPLES OF RADIATION PROTECTION: 1. Distance. 2. Exposure time. 3. Barriers & Shielding.
  57. 57. DISTANCE INVERSE SQUARE LAW: Intensity of radiation is inversely proportional to the square of the distance from the source of radiation. In equation form: For Example: If the dose is 9 R at 3 feet, stepping back to a distance of 6 feet will cause the dose to decrease to 2.25 R.
  58. 58. 57cm from x-ray source 50cm from x-ray source
  59. 59. EXPOSURE TIME  The amount of radiation received is proportional to the length of the exposure time.  Minimized by conducting procedures as quickly as possible.  For Example, using short bursts of fluoroscopy. Employing image intensifiers & Intensifying screens. Using high kVp , low maS techniques.
  60. 60. BARRIERS & SHIELDING  The most commonly used protective material is lead. It has a double advantage of high density and high atomic number.  Lead equivalent: it is the thickness of lead which provide the same degree of protection as the material. ROOM SHIELDING:  Should be located as far as away from areas of high occupancy and general traffic.  Wall on which primary beam falls should not be less than 35 cm thick brick or equivalent.  Shielding of 1.7mm lead (23 cm brick) in front of doors & windows of x-ray room.
  61. 61. X-RAY CONTROL ROOM: Walls & viewing windows of control booth should have lead equivalent of 1.5 mm. Distance between control panel & X-ray unit / chest stand should be minimum 3 meters.
  62. 62. PATIENT WAITING ROOM:  Provided outside X-ray room a proper warning signal when unit is in use.  Warning devices may include audible and visual signs.
  63. 63. LEAD APRON:-  Typically thickness of 0.5 mm lead equivalent is used.  Weight ranges from 2.5 to 7 kg.  Should cover much of red bone marrow & breast. LEAD GLOVES:  Lead salts or metallic lead are added to rubber or plastic.  Lead equivalent of these is about ¼ mm.
  64. 64. LEAD GLASS:  Made by adding lead salts to silicates , in the manufacturing of glass.  It is acceptably transparent and a better protective material.  Contains 60% of lead by weight. GONADAL SHIELDING:  Must be 0.5 mm of lead.  Must be used when gonads will lie within 5 cm of the collimated area.  Separate male vs. female shielding available.
  67. 67.  Have standard projections for specific indications.  Additional views - on a case-by-case basis  Use PA projections, where practical, for chest and spine radiographs.  Avoid repeating exposures.  Use safe exposure factors – high KVp and low mAs technique. Never stand in the primary beam. Always wear protective apparel when not behind a protective barrier. Always wear a radiation monitor and position it outside the protective apron at collar level. The person holding the patient must wear protective apron and if possible gloves. Always collimate to smallest field size appropriate to examination.
  68. 68. RADIATION MONITORING DEVICES Non-Self Reading Devices: 1) FILM BADGES:  Consist of a small dental–sized film wrapped in light proof paper and mounted in a holder filled with metallic filters of different thicknesses. 2) THERMOLUMINESCENT DOSIMETERS (TLD):  They are used to measure external individual whole body doses from X-rays , beta rays & gamma radiation.  It consists of a TLD card loaded in a cassette (card holder ) having suitable metallic & plastic filters.
  69. 69. TLD Ring or Finger badges:  Ring or finger badges are worn by fluoroscopists & interventional radiologists who usually receive high doses to their extremities.  The ring dosimeter contains a small radiation-sensitive lithium fluoride crystal.
  70. 70. SELF READING DEVICES: Real time dose information available Needs frequent Calibration checks Can be taken from hospital to hospital. Good for visiting consultants surgeons, anesthetists, urologists, gastroenterologists etc.
  71. 71. Summary  Ionizing radiation use should be only used when benefit outweighs possible risks.  Every examination should be justified.  Optimized protocols for lowering patient dose without affecting accurate diagnosis should be done.  Use all kinds of radiation protection during work...It's your life.!
  72. 72. Where to Get More Information (1) • The 2007 Recommendations of the International Commission on Radiological Protection, ICRP 103, Annals of the ICRP 37(2-4):1-332 (2007) • UNSCEAR 2008 Report to the General Assembly, with scientific annexes, United Nations Scientific Committee on the Effects of Atomic Radiation, United Nations, Vienna, Austria, 2008 • Avoidance of radiation injuries from medical interventional procedures. ICRP Publication 85. Ann ICRP 2000;30 (2). Elsevier IAEA 3 : Biological effects of ionizing radiation 75