The effective dose (EfD) is measured in which unit?

The effective dose (EfD) is measured in which unit?

• A. Coulombs per kilogram (C/kg)
• B. Gray (Gy)
• C. Sievert (Sv)
• D. Becquerel (Bq)

Answer: (C)

EfD quantifies radiation risk, not just energy deposited. It starts with absorbed dose in grays (Gy) and applies weighting factors for radiation type and for tissue sensitivity, yielding a measure of biological effect in joules per kilogram. That combination defines the sievert (Sv), the unit for effective dose. In practice, medical exposures are often given in millisieverts (mSv) because the amounts are smaller. Other units like coulombs per kilogram (C/kg) describe exposure or kerma, gray (Gy) is absorbed dose, and becquerel (Bq) is activity—these don’t directly represent the risk-adjusted dose used for EfD.

EfD quantifies radiation risk, not just energy deposited. It starts with absorbed dose in grays (Gy) and applies weighting factors for radiation type and for tissue sensitivity, yielding a measure of biological effect in joules per kilogram. That combination defines the sievert (Sv), the unit for effective dose. In practice, medical exposures are often given in millisieverts (mSv) because the amounts are smaller. Other units like coulombs per kilogram (C/kg) describe exposure or kerma, gray (Gy) is absorbed dose, and becquerel (Bq) is activity—these don’t directly represent the risk-adjusted dose used for EfD.