How do free radicals form in living tissue during x-ray exposure?

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Multiple Choice

How do free radicals form in living tissue during x-ray exposure?

Free radicals form mainly from radiolysis of water. In living tissue, water is abundant, so ionizing x-ray photons most often interact with water molecules and eject electrons, splitting H2O into reactive species such as hydroxyl radicals, hydrogen atoms, and hydrated electrons. These radicals diffuse and rapidly react with biomolecules like DNA, causing damage—the indirect effect of radiation. Direct ionization of DNA can occur, but it contributes less to radical formation than water radiolysis. Mitochondria don’t filter out these reactive species to produce them; they are not the primary source of radicals generated by x-ray exposure.

Free radicals form mainly from radiolysis of water. In living tissue, water is abundant, so ionizing x-ray photons most often interact with water molecules and eject electrons, splitting H2O into reactive species such as hydroxyl radicals, hydrogen atoms, and hydrated electrons. These radicals diffuse and rapidly react with biomolecules like DNA, causing damage—the indirect effect of radiation. Direct ionization of DNA can occur, but it contributes less to radical formation than water radiolysis. Mitochondria don’t filter out these reactive species to produce them; they are not the primary source of radicals generated by x-ray exposure.

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