1、Alpha Particles: 2 neutrons and 2 protons They travel short distances, have large mass Only a hazard when inhaled,Four Primary Types of Ionizing Radiation: Alpha Particles,Four Primary Types of Ionizing Radiation: Beta Particles,Beta Particles: Electrons or positrons having small mass and variable e
2、nergy. Electrons form when a neutron transforms into a proton and an electron or:,Four Primary Types of Ionizing Radiation: Gamma Rays,Gamma Rays (or photons): Result when the nucleus releases Energy, usually after an alpha, beta or positron transition,Four Primary Types of Ionizing Radiation: X-Ray
3、s,X-Rays: Occur whenever an inner shell orbital electron is removed and rearrangement of the atomic electrons results with the release of the elements characteristic X-Ray energy,Four Primary Types of Ionizing Radiation: Neutrons,Neutrons: Have the same mass as protons but are unchargedThey behave l
4、ike bowling balls,Four Primary Types of Ionizing Radiation,Alpha particles Beta particles Gamma rays (or photons) X-Rays (or photons) Neutrons,RADIATION FUNDAMENTALS ATOMIC AND NUCLEAR STRUCTURE,Bureau of Radiation Control,Radioactivity: Elements & Atoms,Atoms are composed of smaller particles refer
5、red to as: Protons Neutrons Electrons,Ionization,Ionizing radiation is produced by unstable atoms. Unstable atoms differ from stable atoms because they have an excess of energy or mass or both. Unstable atoms are said to be radioactive. In order to reach stability, these atoms give off, or emit, the
6、 excess energy or mass. These emissions are called radiation.,Types or Products of Ionizing Radiation,or X-ray,neutron,Radioactive Atom,X-ray,gamma ray,Radioactive Atom,X-ray,gamma ray,Direct Ionization Caused By:,ProtonsAlpha ParticlesBeta ParticlesPositron Particles,Indirect Ionization Caused By:,
7、NeutronsGamma RaysX-Rays,DNA and Radiation,Ionizing Radiation at the Cellular Level,Causes breaks in one or both DNA strands or;Causes Free Radical formation,Commonly Transported Radioisotopes,Americium-241= Diagnose thyroid disorders, smoke detectors. Cesium-137= Cancer treatment. Iodine-125,131= D
8、iagnosis localization of brain tumors.,Radiation Measurement,Terminology: Exposure rate = amount radiation possible to receive per unit time. Dose = total amount of radiation received.,Radiation and Radioactivity: Units and Quantities,Department of Health Bureau of Radiation Control,Introduction,Qua
9、ntities (mass, volume, time, etc.) vs. Units (grams, gallons, hours) Units of exposure, radioactivity, and energy associated with ionizing radioactivity As hours and minutes are to time .,Objectives,Define ROENTGEN, RAD, REM, CURIE, GRAY, SIEVERT, BECQUEREL. SI units vs. Standard English units Discu
10、ss the use and conversion of unit prefixes Transform units using “unit analysis”,Background,Early risk associated with use of ionizing radiation skin erythema dose - 25yrs 1928 - ROENTGEN introduced by ICRP,Roentgen,Roentgen,Pronounced rentgen with a hard “g” Limitations only applies to photons only
11、 applies in air only applies to energies less than 3 MeV,Named after Wilhelm C. Roentgen (thus the abbr. is capital “R”),rad,rad,1 rad = 1 Roentgen,rem,rem,The unit of dose equivalent for any type of ionizing radiation absorbed by body tissue in terms of estimated biological effect - Unit of dose eq
12、uivalent Dose in health record is in units of rem 1 rem = 1 Roentgen,Roentgen Equivalent Man,Quality Factor (Q),The specific value that accounts for the ability of different types of ionizing radiation to cause varying degrees of biological damage X-rays, gamma rays, & beta particles 1 Neutrons & Hi
13、gh energy protons 10 Alpha Particles 20,Curie (Ci),Radiation hazard does not solely depend on the activity. It also depends on the type of decay (alpha, beta, photon, etc.),Named in honor of Pierre Curie,SI Radiation Protection Units,Becquerel (Bq) for Curie1 Ci = 3.7 x 1010 Bq Gray (Gy) for rad1 Gy
14、 = 100 rad Sievert (Sv) for rem1 Sv = 100 rem,Unit Analysis,BASE UNIT CONVERSION TABLEUnit Unit Conversion1 Bq 2.7 x 10-11 Ci1 Ci 3.7 x 1010 Bq 1 Bq 1 dis/sec1 dis/sec 2.7 x 10-11 Ci1 Ci 3.7 x 1010 dis/sec,Unit Analysis (Cont.),BASE UNIT CONVERSION TABLEUnit Unit Conversion1 rem 0.01 Sv1 Sv 100 rem1
15、 rad 0.01 Gy1 Gy 100 rad1 R 2.58 x 10-4 C/kg1 meter 3.28 ft (39.37in),Summary,Radiation Protection unit definitions (including SI units) Unit Prefixes Unit conversions,Old Terms,Roentgen-Based on the quantity of electrical charges produced in air by X or Gamma photons 1R=2 billion prRAD-Radiation Ab
16、sorbed Dose is the work energy resulting from the absorption of one ROENTGEN or 6.24 E5 Mev,More Old Terms,REM- Roentgen Equivalent Mammal is equal to the absorbed does in RADS multiplied by a quality factor Quality Factors Beta = 1 Gamma & X ray photons = 1 Alpha = 10 Neutrons = 20,New Terms sort o
17、f,International Units have replaced the RAD and REMGRAY (Gy) = 100 RAD SIEVERT (Sv) = 100 REMSame Quality Factors apply to the Sv,Units of Radioactivity,Curie (Ci) = 2.22 E12 dpm or 3.7E10 dps Becquerel (Bq) = 1 dps Maximum Dose/year = 5 REM or 50 mSv Maximum Dose/year for Declared Pregnant Woman &
18、Minors= 0.5 REM or 5 mSv,Half Life Calculation,Annual Dose Limits,External/Internal Exposure Limits for Occupationally Exposed Individuals,*Effective dose equivalent,Dose Response Relationships,0-150 remNo or minimal symptoms 150-400 remModerate to severe illness 400-800 remSevere illness deaths sta
19、rt above 500 rem Above 800 remFatal*Acute whole body doses,Your Annual Exposure,Estimated Exposure To The National Population,Between 320 360 mr/yr,Another Look at Sources,Some Exposure Limits,2 mr/hr Dose rate to public / Federal 500 mr Emergency responder limit / State/BRC 5 r/yr Occupational /Fed
20、eral 5 r/hr Turn back value / State/BRC 10 r Property / Federal 25 r Life saving / Federal25r Volunteers only / FederalRef - 10CFR PART 20, EPA 400, FL-SOP,Security,All Radioactive Materials must be secured or under direct supervision at all times There MUST be someone in the room at all times OR th
21、e door must be locked.,Spill Response,On Skinflush completely On Clothingremove If Injuryadminister first aid Radioactive Gas Releasevacate area, shut off fans, post warning Monitor all persons and define the area of contamination,ALARA,As Low As Reasonably Achievablemeans making every reasonable ef
22、fort to maintain exposures to radiation as far below the dose limits as is practicable consistent with the purpose for which the licensed activity is undertaken, taking into account the state of technology, the economics of improvements in relation to the state of technology, the economics of improvements in relation to benefits to the public health and safety, and other societal and socioeconomic considerations, and in relation to utilization of nuclear energy and licensed materials in the public interest.,Radiation Protection,Decrease TimeIncrease DistanceIncrease Shielding,
