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Lecture19BiolEffectsofRadiation_001

Lecture19BiolEffectsofRadiation_001 - Lecture 19 Biological...

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Lecture 19: Biological Effects of Radiation I. Radiation Chemistry Interaction of Radiation with Matter: Emphasis on effect of medium on incident radiation Biological Effects of Radiation: Emphasis on effect of radiation on medium A. Chemical Species Formed in Medium 1. Cation-Electron Pairs a. Gases and Liquids mobile ions – facilitates detection e.g., CH 4  CH 4 + + e biological systems: alters electrolyte balance b. Solids trapped electrons and lattice defects modified conduction bands: impurities, Si bit upsets 2. Free Radicals Bond cleavage CH 4  CH 3 + H a. Radioalysis: Decomposition of compounds; esp. H 2 O, by radiation H 2 O  H + OH H + H H 2 (reducing agent) Body mostly H 2 O OH + OH H 2 O (oxidizing agent) TMI b. Compounds C x H y O z  CO 2 , H 2 O, H 2, etc. recombinants may alter properties – negative or positive Negative: biological alterations (DNA) Positive: cross-linking of polymers (Cook, Inc.) dE/dx AZ 2 /E for charged particles dE/dx E for photons hv hv hv can improve qualities of polymers
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