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PRACTICAL RADIATION PHYSICS FOR EMERGENCY MEDICAL PERSONNEL Module III

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- 2 What is radiation?

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Module III - 3 Ionizing radiation

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Module III - 4 Electromagnetic radiation GAMMA VISIBLE X-RAYSCOSMIC INFRAREDULTRAVIOLET MICROVAVES TV, RADIO Decreasing wave length Increasing frequency Increasing photon energy IONIZING RADIATON

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Module III - 5 Forms of ionizing radiation Particulate radiation Electromagnetic radiation consisting of atomic or subatomic particles (electrons, protons, etc.) which carry energy in the form of kinetic energy of mass in motion in which energy is carried by oscillating electrical and magnetic fields travelling through space at speed of light Directly ionizing Indirectly ionizing

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Module III - 6 Origin of radiation What is the relationship between atom structure and radiation production?

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Module III - 7 Atom anatomy Electron ProtonNeutron Nucleons

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Module III - 8 Isotopes

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Module III - 9 Why are some nuclides radioactive ? Why are some nuclides radioactive ? Neutron to proton ratio

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Module III - 10Half-life

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Module III - 11 The number of decaying nuclei per unit of time The Systéme International (SI) unit of radioactivity is the Becquerel (Bq) One Bq = 1 disintegration per second Non-SI unit of radioactivity is the Curie (Ci) One Ci = 3,7 x 10 10 transformations per second One milicurie (mCi) = 3,7 x 10 7 s -1 One microcurie (μCi) = 3.7 x 10 4 s -1 1 Bq = 2.7 x 10 -11 Ci Activity

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Module III - 12 Atomic symbols A XNXN Z SYMBOL OF ELEMENT MASS NUMBER (the number of protons and neutrons) ATOMIC NUMBER (the number of protons) 53 I 78 131 Example: 131 I or I-131 The number of neutrons

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Module III - 13 E= mc 2 Measured Mass Calculated Mass Mass-energy relationship

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Module III - 14 Fission

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Module III - 15 Nuclear reaction and energy production

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Module III - 16 Mechanisms of radioactive decay

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Module III - 17 A Z X A-4 Z-2 Y + 4 2 He e.g. 238 92 U 234 90 Th + 4 2 He Alpha (α ++ ) decay

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Module III - 18 n p + e - + υ A Z X A Z+1 Y +e - + e.g. 131 53 I 131 54 Xe+e - + Beta ( - ) decay

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Module III - 19 p n + e + + υ A Z X A Z-1 Y+e + + e.g. 18 9 F 18 8 O+e + + Positron ( + ) decay

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Module III - 20 Electron capture p + + e - n + A Z X A Z-1 Y + 125 53 I 125 52 Te+

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Module III - 21 Gamma ( ) emission

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Module III - 22 SIMPLIFIED NUCLEAR MODEL Gamma ray Nuclear energy levels: gamma radiation

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Module III - 23 How does radiation interact with matter?

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Module III - 24 Excitation

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Module III - 25 Ionization Electron removal by ionization

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Module III - 26 Alpha particle interaction

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Module III - 27 Interaction of alpha radiation with living matter: external deposition l Alpha radiation is not external hazard. l The maximum range in tissue is <0.1 mm l All alpha radiation is absorbed in stratum corneum

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Module III - 28 Interaction of alpha radiation with living matter: internal deposition Prime danger is inhalation and ingestion of alpha emitter

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Module III - 29 Beta interaction with matter

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Module III - 30 Interaction of beta radiation with living matter I I I I I ı 0.001 0.01 0.1 1 10 100 Cell nucleus Cell diameter 100 cell diameter Auger 5.3 MeV alpha 0.15 MeV beta 1.7 MeV beta mm beta alpha

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Module III - 31 Positron interaction: annihilation reaction

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Module III - 32 Neutron interaction

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Module III - 33 Neutron activation

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Module III - 34 Interaction of gamma radiation with matter l In terms of ionization, gamma radiation interacts with matter in three main ways 1. Photoelectric effect 2. Compton scattering 3. Pair production

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Module III - 35 Gamma interaction by photoelectric effect

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Module III - 36 Gamma interaction by Compton scattering

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Module III - 37 Pair production

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Module III - 38 Extranuclear energy release l Bremsstrahlung radiation l Characteristic X rays l Auger electrons

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Module III - 39 Bremsstrahlung radiation

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Module III - 40 Importance of bremsstrahlung X rays in radiation safety practice

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Module III - 41 Characteristic X rays

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Module III - 42 Difference between X rays and gamma rays

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Module III - 43 Internal conversion: Auger electrons

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Module III - 44 Specific ionization and linear energy transfer (LET)

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Module III - 45 Penetrating power of radiation

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Module III - 46 Review points l Characteristics of representative types of ionizing radiation particulate, charged, and directly ionizing radiation of alpha and beta particles particulate, uncharged, and indirectly ionizing radiation of neutrons electromagnetic, uncharged, and indirectly ionizing radiation of gamma rays and X rays. l Radiation interacts with matter via two main processes: ionization and excitation l Energy, which comes in many forms, can be converted from one form to another l Nuclear potential energy is converted into kinetic energy through nuclear fission l Conversion of mass to energy was predicted by Albert Einstein in his mass-energy equation, E = mc 2 l Penetrating power of ionizing radiation is relative to radiation type and energy

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