Question

Which of these phrases is correlated with sieverts? Check all that apply.

one disintegration per second

one joule of energy per kilogram of matter

number of disintegrations of radioactive atoms over a period of time

radiation dose absorbed by any material

radiation dose absorbed by biological tissue

measurement of emitted radiation

measurement of radiation dose

measurement of biological risk

Answer 1

Select the ones that apply to the sievert (Sv):

- one joule of energy per kilogram of matter — Yes (unit-wise 1 Sv = 1 J/kg), but with a caveat: J/kg as a raw absorbed-energy unit is the gray (Gy). Sievert uses the same base units but includes weighting factors to express biological effect.
- radiation dose absorbed by biological tissue — Yes. Sv is used for dose quantities that represent biological effect (equivalent dose, effective dose) on tissue.
- measurement of radiation dose — Yes, when used to mean the dose expressed as biological effect (equivalent/effective dose). If you mean purely absorbed energy in any material, that’s the gray (Gy).
- measurement of biological risk — Yes. Sv is intended to quantify the potential biological harm (risk) from ionizing radiation.

Not applicable to sieverts:

- one disintegration per second — No (that’s the becquerel, Bq).
- number of disintegrations of radioactive atoms over a period of time — No (activity; Bq or curie).
- radiation dose absorbed by any material — No (absorbed dose in any material is the gray, Gy).
- measurement of emitted radiation — No (emitted radiation intensity/activity is not measured in sieverts).