At 211
7.2 h
ε
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% ɑ emission to stable Pb-207. Moreover, At-211 decays by 41.8% ɑ 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 ɑ emission is 100% per At-211 decay with an average ɑ 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 γ-rays at 567.7 keV (0.31%), 687.0 keV (0.26%) and 897.8 keV (0.32%).

The mean ɑ 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.

Production

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

Distribution

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

preclinical

No carrier added (n.c.a.)

Yes
ParameterSpecifications
Production routeBi-209(α,2n) At-211
DaughterDecays to Po-211 which decays immediately (T1/2=0.5 s) to stable Pb-207 and Bi-207 that is quasi-stable (T1/2=31.6 y): cumulative 100% α, 100% EC
Half-life7.21 h
ProcessingDry extraction
Primary Container2.5 mL borosilicate glass V-vial with silicon rubber screw cap
Product Graden.c.a.
Physical FormSolid
Chemical FormChloroform
Radioactive Concentration (gamma spectrometry)n.a.
AppearanceClear colourless solution
Radionuclide identification (gamma spectrometry)570 keV, 687 keV and 898 keV gamma lines present
Radionuclidic Purity (gamma spectrometry)At-210/At-211 < 0.5%
Chemical purity (ICP-OES)n.a.
Molar activity (ICP-OES)n.a.
Apparent Molar Activityn.a.
Microbiological qualityn.a.
Bacterial endotoxinn.a.
pH (pH strips)n.a.
Additional information
Activity availableTens of MBq on demand
Activity limit for UN2910 (excepted package) shipment0.5 GBq in dry state or 50 MBq in liquid form
Other information

Applications

  • α-therapy

Point of supply

  • Nantes, France

Involved production facilities

ARRONAX, France