☢️ Radionuclide Decay Calculator
Compute remaining radionuclide activity from physical half-life, with % remaining, elapsed half-lives, and optional time to a target %. Instant, browser-side.
Presets use commonly cited physical half-lives.
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When to use
Post-injection remaining activity, elution hold time, decay-correction checks, teaching. Physical decay only.
How it works
A = A0 · e^(−λt), λ = ln2 / T½. Half-lives converted to hours. 1 mCi = 37 MBq.
Key points
- Presets use commonly cited physical half-lives.
- Optional time-to-target %.
- No biological clearance.
References
- ICRP / chart of the nuclides — physical half-lives (Tc-99m, F-18, I-131, etc.)
Worked calculation
The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.
| Nuclide | Tc-99m (6.01 h) |
|---|---|
| Initial activity A0 | 10 |
| Activity unit | mCi |
| Elapsed time (hours) | 6 h |
| Extra minutes (optional) | 0 min |
| Target % remaining (optional) | 10 % |
→Remaining activity5.0058mCi
- % remaining：50.06 %
- Elapsed half-lives：0.998
- Other unit：185.2135 MBq
Frequently asked questions
- What is Radionuclide Decay Calculator?
- Compute remaining radionuclide activity from physical half-life, with % remaining, elapsed half-lives, and optional time to a target %. Instant, browser-side.
- How is Radionuclide Decay Calculator calculated? What is the core formula?
- A = A0 · e^(−λt), λ = ln2 / T½. Half-lives converted to hours. 1 mCi = 37 MBq.
- When is Radionuclide Decay Calculator used?
- Post-injection remaining activity, elution hold time, decay-correction checks, teaching. Physical decay only.
- What are the key clinical points for Radionuclide Decay Calculator?
- Presets use commonly cited physical half-lives. Optional time-to-target %. No biological clearance.
- What are the limits and cautions when using Radionuclide Decay Calculator?
- For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
- How is Radionuclide Decay Calculator calculated in practice? Can you show a worked example?
- Inputs: Nuclide Tc-99m (6.01 h), Initial activity A0 10, Activity unit mCi, Elapsed time (hours) 6 h, Extra minutes (optional) 0 min, Target % remaining (optional) 10 % → Result: Remaining activity 5.0058 mCi（% remaining: 50.06 %, Elapsed half-lives: 0.998, Other unit: 185.2135 MBq）
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