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Lecture. Ionizing Radiation and Health.ppt - Ionizing...

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1Ionizing Radiation
2RadiationRadiation: energy being transmitted through spaceAll life is dependent on small doses of electromagnetic radiation.Ionizing radiationis radiation with sufficient energy forproducing ions when interacting with matter - in otherwords enough energy to remove an electron from anatom; this process is calledionizationSources: x-rays, radioactive material produce alpha, beta, andgamma radiation, cosmic rays from the sun and space.Non-ionizing radiationis radiation without sufficientenergy to produce ionizationSources: ultraviolet, visible, infrared, microwaves, radio & TV,power transmission
310-1410-1210-1010-810-610-410-21102104106108Wavelength in Meters1010108106104102110-210-410-610-810-1010-1210-14BroadcastShort waveTVFMRadarInfraredNearFarVisibleUltravioletX RaysGamma RaysCosmic RaysPowerTransmissionIonizing RadiationNonionizing RadiationEnergy - Electron VoltsHighLowElectromagnetic Spectrum
4Ionizing RadiationEnergyLowMediumHigh
Alpha ParticlesAlpha particlesTwo neutrons and two protons (mass #: 4; charge:+2)Produced by elements with high atomic numbersEmitted from nucleus of radioactive atomsTransfer energy in very short distancesIn air: 10 cmShielded by paper or dead outer layer of skinHealth effectsPrimary hazard from internal exposureCan accumulate in tissues (e.g. bone, kidney, liver, lung),interact electronically with these tissues, and cause localdamage.No protective dead skin layer internally to shield the organs/tissues5
6Beta ParticlesBeta particlesSmall electrically charged particles similar to electrons (charge: -1)Ejected from nuclei of radioactive atomsPenetration power is greater than alpha particlesIn wood: 4 cm;Human body: 0.2 to 1.3 cmShielded by aluminum and organo-plasticsHealth effectsInternal hazard, but relatively more hazardous externally than alphaparticlesMuch smaller and have less charge than alpha particlesbeta particlestravel further into tissuesthe cellular damage is more dispersed.Since several beta emitters (e.g. strontium-90, iodine-131) arechemically similar to naturally occurring bodily constituents, they maysubstitute for those elements and concentrate in living tissues (e.g.bones, thyroid), where they continue to emit radiation for an extendedperiod of time, increasing the risk of cancer or mutations.Skin burns from extremely high doses of beta radiation.
7X-Rays and Gamma RaysX-rays and Gamma-raysBoth are electromagnetic photons (No mass, charge=0,speed=C)Different in emission source:X-ray: emitted from electron orbits, e.g. when an excited orbitalelectron "falls" back to a lower energy orbitGamma ray: spontaneous emission from the nucleus of a atom;

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