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Concerning radiation damage to tissues, which of the following are correct? a. It is caused directly by photo electrons b. Cells with high mitotic rates are less affected c. It is caused by free radicals d. Secondary electrons cause damage to tissue in a linear pattern e. It is caused directly by X-rays |
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Answer» a. True. When secondary electrons (e.g. photo electrons and recoil electrons) pass through tissue, they result in ionization and excitation of atoms resulting in tissue damage. b. False. Cells with higher mitotic levels are more prone to radiation damage. c. True. Ionization by secondary electrons, results in damage to biological tissue either by rupturing covalent bonds or by the production of free radicals, which result in oxidation of organic molecules. d. False. Secondary electrons have a tortuous path, as negative electrons easily deflect them, leaving a track of ionized atoms behind. e. False. X-rays and gamma rays result in ionization of atoms via secondary electrons and are therefore indirectly ionizing agents. |
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