Why does damage via the Indirect theory occur more frequently than direct hits?

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Multiple Choice

Why does damage via the Indirect theory occur more frequently than direct hits?

Indirect damage dominates because cells are mostly water. When ionizing radiation passes through a cell, it interacts far more often with water molecules than with DNA. Ionization of water produces reactive free radicals, especially hydroxyl radicals, which diffuse and attack DNA and other biomolecules. These radicals can cause strand breaks and base damage long after the initial interaction. Since there are vastly more water molecules than DNA targets, most radiation-induced damage arises from these indirect effects rather than from direct hits to the DNA itself. Direct hits require energy to deposit directly into DNA, a small and relatively unlikely target, so they contribute less to the total damage.

Indirect damage dominates because cells are mostly water. When ionizing radiation passes through a cell, it interacts far more often with water molecules than with DNA. Ionization of water produces reactive free radicals, especially hydroxyl radicals, which diffuse and attack DNA and other biomolecules. These radicals can cause strand breaks and base damage long after the initial interaction. Since there are vastly more water molecules than DNA targets, most radiation-induced damage arises from these indirect effects rather than from direct hits to the DNA itself. Direct hits require energy to deposit directly into DNA, a small and relatively unlikely target, so they contribute less to the total damage.

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