Integrated Activity (0 → t)
Total decays over a time window. You give the starting activity A₀ and a duration. We add it up.
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Example: Tc‑99m, F‑18, Lu‑177, I‑131, etc.
This is the activity right at time 0 of your interval.
Example: to sum one day, enter 24 and choose hours.
Your result will appear here.
What’s happening under the hood?
We integrate the decay curve from 0 to t:
∫₀ᵗ A₀·e^{−λτ} dτ = (A₀/λ)(1 − e^{−λt}), where λ = ln(2)/T½.
Units are Bq·s, which is numerically equal to the expected number of decays in that time.