放射性是不稳定原子核因辐射失去能量的过程。它以Becquerels（BQ）进行测量。
1 rem = 0.01 β
1 β = 100 rem
例子:
将15 REM转换为beta颗粒：
15 rem = 0.15 β
| REM | beta颗粒 |
|---|---|
| 0.01 rem | 0 β |
| 0.1 rem | 0.001 β |
| 1 rem | 0.01 β |
| 2 rem | 0.02 β |
| 3 rem | 0.03 β |
| 5 rem | 0.05 β |
| 10 rem | 0.1 β |
| 20 rem | 0.2 β |
| 30 rem | 0.3 β |
| 40 rem | 0.4 β |
| 50 rem | 0.5 β |
| 60 rem | 0.6 β |
| 70 rem | 0.7 β |
| 80 rem | 0.8 β |
| 90 rem | 0.9 β |
| 100 rem | 1 β |
| 250 rem | 2.5 β |
| 500 rem | 5 β |
| 750 rem | 7.5 β |
| 1000 rem | 10 β |
| 10000 rem | 100 β |
| 100000 rem | 1,000 β |
规则