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INTERNATIONAL SCIENCE AND TECHNOLOGY CENTER
Project # 245 "Radleg"
UNITS of MEASUREMENT
Radionuclides’ activity and radiation dose values, as a rule, are presented in the Overview in the International System of units:
| Becquerel (Bq) |
- a unit of radionuclide activity in a radiation source. 1 Bq corresponds to 1 decay per second for any radionuclide. |
| Gray (Gy) |
- a unit of absorbed dose. 1 Gy = 1 J/kg |
| Sievert (Sv) |
- a unit of equivalent dose. For X-ray, gamma- and beta-radiation 1 Sv corresponds to absorbed dose of 1 J/kg. |
| Non-system units |
- are used in the Overview either in parallel, or in those cases, when official sources are cited or primary measurements’ data, taken from original publications, are presented: |
| Curi (Ci) |
- a non-system unit of radionuclide activity in a radiation source. 1 Ci = 3.7x1010Bq |
| Roentgen (R) |
a non-system unit of exposure dose. 1 R = 2.58x10-4 C/kg. |
If the energy of an ion pair formation in the air at 0°
C and 760 mm Hg is taken as equal to 34 eV, 1 R would correspond to absorbed dose in the air equal to 8.8x10-3 Gy and to absorbed dose in a biological tissue equal to 9.3x10-4 Gy (on the average).
| Rem |
- a non-system unit of equivalent dose (a biological equivalent of roentgen). 1 rem = 0.01 Sv |
To form multiple units the next prefixes are used:
| Prefix |
Numeric value |
| micro (m) |
10-6 |
| milli (m) |
10-3 |
| centi (c) |
10-2 |
| kilo (k) |
103 |
| mega (M) |
106 |
| giga (G) |
109 |
| tera (T) |
1012 |
| peta (P) |
1015 |
| exa (E) |
1018 |
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