The reasoning
| Quantity | Question | Conventional unit | SI unit | Conversion |
|---|---|---|---|---|
| Exposure | ionisation produced in air by X/gamma | roentgen (R) | coulomb/kg (C/kg) | 1 R = 2.58 × 10⁻⁴ C/kg |
| Absorbed dose | energy deposited per mass | rad | gray (Gy) = 1 J/kg | 1 Gy = 100 rad |
| Equivalent dose | absorbed dose × radiation weighting factor (wR) | rem | sievert (Sv) | 1 Sv = 100 rem |
| Effective dose | Σ (equivalent dose × tissue weighting factor wT) | rem | sievert (Sv) | population‑level risk comparison |
| Activity | nuclear transformations per second | curie (Ci) | becquerel (Bq) = 1 disintegration/s | 1 Ci = 3.7 × 10¹⁰ Bq (37 GBq) |