更精确的说法:"KI administered up to 48 h before 131-I exposure can almost completely block thyroid uptake and therefore greatly reduce the thyroid absorbed dose. However, KI administration 96 h or more before 131-I exposure has no significant protective effect. In contrast, KI administration after exposure to radioiodine induces a smaller and rapidly decreasing blockade effect. KI administration 16 h or later after 131-I exposure will have little effect on thyroid uptake and absorbed dose and therefore little or no protective effect."
碘只是放甲状腺受到辐设。