Radioactivity Toolkit · MIRF · UBC
Decay & activity,from calibration to disposal.
Convert activity units, decay-correct by the clock, work out how much to draw up, and see the whole day at a glance — built for the preclinical imaging bench.
The Calculator
Four tools, one isotope
Pick an isotope once — every panel below uses the same half-life. Everything updates live; nothing leaves your browser.
Auto-filled from the isotope. Editable for anything not listed.
λ = ln(2) / t½ · per second
Target before calibration? It back-decays automatically to give the original (higher) activity.
—
remaining at target time
Work out when a labelled source can be discarded — held for the UBC standard of 10 half-lives (≈0.1% remaining). Decay-in-storage planning only; always confirm with a survey meter before disposal.
UBC decay-in-storage rule: hold for 10 half-lives (≈0.098% remaining), then survey before release.
—
safe to discard on / after
Before releasing waste — UBC checklist. A decayed date is not automatic clearance. Survey the sealed bag/container with a GM meter: the surface field must read < 2.5 µSv/h (0.25 mR/h), and the activity must fall under the CNSC per-isotope limit (Table 6 — activity/kg for solids, release limit for liquids; e.g. 37 kBq/L for C-14). Solids may not be diluted to meet the limit. Deface all radiation labels, and log the holding date, isotope & activity. When in doubt, confirm with the RSO (research.safety@ubc.ca).
You know the activity you need at scan/injection time. This works backwards to tell you how much to calibrate or draw up at an earlier time — and, optionally, what volume to pull from a stock vial.
Also compute draw-up volume from a stock concentration
e.g. 50 mCi/mL. Concentration is taken at the draw-up time above.
—
to have ready at draw-up time
Converter is independent of the selected isotope — unit conversion only.
Spacing of each table row / curve point.
How far ahead to go: time between rows × number of rows.
| Elapsed | Activity | % remaining |
|---|