Define effective dose and explain its purpose in risk assessment.

• A. The sum of organ doses weighted by tissue factors to estimate overall cancer risk.
• B. The energy deposited per kilogram without weighting factors.
• C. The maximum allowable dose for any organ.
• D. The dose in gray adjusted by exposure time.

Answer: (A)

Effective dose is a single risk-based quantity used in radiation protection. It combines the doses received by each organ or tissue by weighting them with tissue weighting factors that reflect how sensitive each tissue is to radiation-induced stochastic effects, and then sums these weighted doses across all tissues. This produces an overall estimate of cancer and hereditary risk from the exposure, allowing meaningful comparisons between different scenarios and guiding protection decisions for populations. It’s a tool for risk assessment, not a measure of what any one organ receives, not an absorbed dose in gray, and not a regulatory per-organ limit.