Decay Lab is a radionuclide decay calculator for nuclear medicine, built around the decay correction you do every day, rather than as a general-purpose science app.

Decay correction
Enter a reference activity and its calibration time, then read the activity at any other moment. Time runs backwards as well as forwards, so you can ask what a vial held this morning as easily as what it will hold this afternoon.

Live activity
The current activity updates every second, to five significant figures, so short-lived nuclides visibly tick down. Half-lives elapsed and the percentage remaining are shown alongside the target-time result.

What each nuclide is for
Curated nuclides are labelled by role, PET, SPECT, therapy or generator, with icons on the element list, the nuclide list and the calculator itself. Elements used in nuclear medicine are grouped ahead of the rest, so you can see at a glance whether an element holds anything for your work.

1,625 nuclides
A bundled catalogue covering 1,625 nuclides across 97 elements. The ones nuclear medicine actually orders come first: Tc-99m, F-18, Ga-68, Ac-225, Cu-64, In-111, I-131, Pb-212, Lu-177, Tb-161, Y-90 and Zr-89.
440 of those nuclides have more than one energy state, and every state is selectable. Where a state is the one used in the clinic, it is named and preselected.

Units
Bq, kBq, MBq, GBq and TBq, alongside nCi, uCi, mCi and Ci. Choosing a unit labels the number you typed rather than converting it, so entering 37 GBq is exactly that.
A separate converter tab shows one activity in every other unit at once, instead of one pair at a time.

Readable numbers
Results scale to whichever unit reads best, so you see 1.2 GBq rather than 1200000 kBq. Values too large or small for that use proper scientific notation. Half-lives appear the way they are spoken, 109.8 min for F-18, 6.647 d for Lu-177, not as raw decimal hours.

Built for the clinic
Works entirely offline; the catalogue ships with the app. Follows your system light or dark appearance.

Who it is for
Nuclear medicine technologists and physicians, medical physicists, radiopharmacy staff, radiation safety officers, researchers and students working with radionuclides.