At 211
7.2 h
α 5,867...
γ (687)

Chemical properties

In the periodic table astatine is situated at the boundary of halogens and metalloids, i.e. partly behaves like a halogen and partly like a metal. This requires dedicated labelling strategies .

Nuclear properties

At-211 decays with 7.214(7) h half-life. It decays by 58.2% electron capture to short-lived Po-211 (T1/2 = 0.516(3) s) that decays in turn with 100% alpha emission to stable Pb-207. Moreover, At-211 decays by 41.8% alpha emission to quasi-stable Bi-207 (T1/2=31.6 years; only 26 Bq Bi-207 per 1 MBq of At-211 after decay of the latter) that decays in turn to stable Pb-207. Including its short-lived Po-211 daughter, the cumulative alpha emission is 100% per At-211 decay with an average alpha energy of 6.78 MeV.

At-211 emits X-rays, notably Kα at ≈78 keV (33.1(5)%) and Kβ at ≈90 keV (9.06(5)%). These energies enable SPECT-imaging, preferably with medium energy collimators .

Moreover, At-211 and its daughter Po-211 in equilibrium emit weak gamma-rays at 567.7 keV (0.31%), 687.0 keV (0.26%) and 897.8 keV (0.32%).

The mean alpha energy per decay is 6785 keV, the mean recoil energy (of Bi-207 or Pb-207 recoils respectively) is 131 keV, the mean electron energy per decay is 3 keV, and the mean photon energy per decay is 43 keV.


At-211 is produced by alpha particle irradiation of metallic Bi-209 targets at the cyclotron ARRONAX.


The radiochemical separation is performed at ARRONAX (ARRONAX, Nantes, France) and activity will be shipped from there to the users.

Examples of use

  • Clinical trials with At-211-radioimmunotherapy have been performed in the past and are ongoing.

Purity grades available


No carrier added (n.c.a.)

Half-life7.214 h
DaughterPo-211 which decays immediately (T1/2=0.5 s) to stable Pb-207 (stable) and Bi-207 that is quasi-stable (T1/2=31.6 y).
Branching Ratio/Decay41.8 % α, then EC at 100%
58.2% EC, then α at 100%
ProductionBi-209(α,2n) At-211
PurificationDry extraction
Chemical FormChloroform
Specific Activityn.a.
Radionuclidic PurityAt-210/At-211 < 0.5%
Radiochemical Purityt.b.d.
Identification569.7 keV, 687.0 keV and 897.8 keV gamma lines present
AppearanceClear and colourless solution
Activity availableTens of MBq
AvailabilityOn demand
GradePreclinical grade, n.c.a.
Other informationTransport to be discussed.


  • α-therapy

Point of supply

  • Nantes, France

Involved production facilities