Calculate activity before or after radioactive decay
Remaining activity after time t:
\( A(t) = A_0 \times 2^{-t / T_{1/2}} \)
Activity to prepare for target at time t:
\( A_0 = A_{target} \times 2^{t / T_{1/2}} \)
| Nuclide | T½ | Application |
|---|---|---|
| 99mTc | 6.007 h | Bone, kidney, heart, brain, lung, thyroid |
| 18F | 109.77 min | PET with FDG — oncology, neurology, infection |
| 68Ga | 67.71 min | PET with DOTA-peptides (neuroendocrine, PSMA) |
| 123I | 13.22 h | Thyroid, brain, mIBG |
| 131I | 8.021 d | Thyroid therapy, mIBG therapy |
| 67Ga | 3.261 d | Infection, lymphoma (legacy) |
| 111In | 2.805 d | Octreotide, WBC labeling |
| 201Tl | 3.04 d | Myocardial perfusion (legacy) |
This calculator is intended for planning only and does not replace calibrated activity measurement. Verify all activities with a dose calibrator before administration. Half-life values are from ICRP Publication 107 (2008).