Formulas & conversions 1 Curie (Ci) = 2.22 x 10(12) disintegrations/min (dpm) = 37 GBq 1 mCi = 2.22 x 10+9 dpm = 37 MBq 1 µCi = 2.22 x 10+6 dpm = 3.7 X 10+4 Bq = 37 kBq 1 Becquerel (Bq) = 1 disintegration/s (dps) = 2.7 x 10-11 Ci = 2.7 x 10-5 µCi 1 GBq = 27 mCi 1 MBq = 27 µCi 1 kBq = 27 nCi Radioactive decay equation A=Aoe-( 0.693t/T1/2 ) Ao- original activity T - half-life t - elapsed time
System International (SI) Units for Ionizing Radiation
Quantity | Unit Name (Symbol) |
Definition | Former Unit |
Conversion Factor |
---|---|---|---|---|
Activity | Becquerel (Bq) |
Disintegrations/sec | Curie (Ci) |
1 Bq = 2.7 x 10-11 Ci |
Absorbed Dose | Gray (Gy) |
Joule/kilogram | rad | 1 Gy = 100 rads |
Dose Equivalent | Sievert (Sv) |
Joule/kilogram | rem | 1 Sv = 100 rems |
Isotope | Emission | Energy (max) MeV | Half Life |
14C | beta | 0.156 (100%) | 5,730 years |
3H | beta | 0.0186 (100%) | 12.3 years |
35S | beta | 0.167 (100%) | 87.4 days |
125I | gamma - X-ray | 0.035 - 0.027, 0.031 | 60.14 days |
51Cr | gamma - X-ray - Auger | 0.320 | 27.7 days |
33P | beta | 0.249 (100%) | 25.4 days |
32P | beta | 1.709 (100%) | 14.3 days |
131I | gamma - beta | 0.364 - 0.61 | 8.04 days |
111In | gamma - X-ray (& others) | 0.171 - 0.023, 0.026 | 2.83 days |
123I | gamma, ec | 0.159 | 13 hours |
99mTc | gamma | 0.140 | 6.01 hours |