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EJNMMI Radiopharmacy and Chemistry

Table 1 Decay of Ac-225 to daughter nuclides and their emission/yield

From: Implementing Ac-225 labelled radiopharmaceuticals: practical considerations and (pre-)clinical perspectives

Decaying isotope

Half-life (t1/2)

α emission*

β emission

γ emission

Ac-225

9.92 d

5.8 MeV

x

150 keV (0.6%)

188 keV (0.45%)

Fr-221

4.8 m

6.3 MeV

x

218 keV (11.4%)

At-217

32 ms

7.1 MeV

x

x

Bi-213

46.6 m

5.9 MeV (2.1%)

1.4 MeV (97.8%)

440 keV (25.9%)

Po-213

4.2 µs

8.4 MeV

x

x

Tl-209

2.2 m

x

2.0 MeV

x

Pb-209

3.3 h

x

0.6 MeV

x

Bi-209

Stable

x

x

x

  1. *α-Emission leads to recoil from the radiopharmaceutical construct, all daughter nuclides from Ac-225 are ejected outside of the chelate upon Ac-225 decay, see “Equilibrium” section
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