Question

Which statements are correct about Becquerel (Bq) and Gray (Gy) units? Check all that apply.

Gray units measure the number of disintegrations of radioactive atoms over a period of time.

Gray units measure the radiation dose absorbed by any material.

Becquerel units measure the radiation dose absorbed by biological tissue.

Becquerel units measure emitted radiation.

Gray units measure radiation dose.

Gray units measure biological risk.

Answer 1

Correct statements (check these):

- Gray units measure the radiation dose absorbed by any material. — True. Gray (Gy) = joule per kilogram; it is the absorbed dose (energy deposited per mass) in any material.
- Becquerel units measure emitted radiation. — True (with nuance). Becquerel (Bq) is the activity (one disintegration per second), i.e., the rate at which radioactive atoms decay and thus emit radiation.

Also correct in intent:

- Gray units measure radiation dose. — True (Gy is the SI unit of absorbed dose).

Incorrect statements:

- Gray units measure the number of disintegrations of radioactive atoms over a period of time. — False. That is what activity units (Bq, Ci) measure.
- Becquerel units measure the radiation dose absorbed by biological tissue. — False. Dose is measured in gray (Gy); biological effect is expressed in sievert (Sv).
- Gray units measure biological risk. — False. Biological risk is represented by sievert (Sv), which weights absorbed dose (Gy) by radiation type and tissue sensitivity.