If two tissues receive the same organ dose, which statement is true regarding their contribution to the effective dose?

If two tissues receive the same organ dose, which statement is true regarding their contribution to the effective dose?

• A. The tissues contribute equally regardless of WT.
• B. The tissue with the higher tissue weighting factor WT contributes more to the effective dose.
• C. Only the tissue with the lower WT contributes.
• D. WT is ignored when organ doses are equal.

Answer: (B)

Effective dose combines how much radiation a tissue receives with how sensitive that tissue is to radiation. The calculation weights each tissue’s dose by its tissue weighting factor, so the contribution to the overall effective dose is proportional to both the tissue dose and its wT. If two tissues receive the same organ dose, their equivalent doses are effectively the same (assuming the same radiation type), and the tissue with the higher weighting factor will contribute more to the effective dose because its larger wT scales that shared dose to a bigger risk contribution. In short, when doses are equal, the tissue with the higher tissue weighting factor adds more to the overall effective dose.

Effective dose combines how much radiation a tissue receives with how sensitive that tissue is to radiation. The calculation weights each tissue’s dose by its tissue weighting factor, so the contribution to the overall effective dose is proportional to both the tissue dose and its wT. If two tissues receive the same organ dose, their equivalent doses are effectively the same (assuming the same radiation type), and the tissue with the higher weighting factor will contribute more to the effective dose because its larger wT scales that shared dose to a bigger risk contribution. In short, when doses are equal, the tissue with the higher tissue weighting factor adds more to the overall effective dose.