Chemical properties
Bi-213 is usually employed in trivalent state. It can be labelled with macrocyclic chelators such as DOTA, but other chelators can be considered too . The ionic radius is 117 pm.
Nuclear properties
Bi-213 decays with a half-life of 0.760(1) hours. It decays by 97.8% beta-minus emission to very short-lived Po-213 (T1/2 = 3.7 µs) that decays in turn with 100% alpha emission to Pb-209 (T1/2 = 3.2 h), further decaying by beta-minus emission to Bi-209. Moreover, Bi-213 decays by 2.2% alpha emission to Tl-209 (T1/2=2.16 min) that decays via Pb-209 to Bi-209. Including its short-lived Po-213 daughter, the cumulative alpha emission is 100% per Bi-213 decay with an average alpha energy of 8.32 MeV.
Bi-213 emits gamma rays at 440.5 keV (25.94(15)%). This enables SPECT-imaging with high energy collimators .
Production
Ac-225 is produced by elution from Th-229 generators. It is loaded onto a generator from which Bi-213 can be eluted .
Distribution
Bi-213 generators will be shipped from the PRISMAP production facility JRC Karlsruhe (JRC, Karlsruhe, International).
Examples of use
| Parameter | Specifications |
|---|---|
| Half-life | 9.92 d for Ac-225 mother, 45.6 min for Bi-213 eluate |
| Daughter | Decay chain of Bi-213 involves radioactive Po-213 or Tl-209 and Pb-209, leading to Bi-209. |
| Branching Ratio/Decay | Cumulative 100% α, 200% β- |
| Production | Th-229→ Ra-225 → Ac-225 generator |
| Purification | two step purification process (cation exchange and extraction chromatography) |
| Chemical Form | n.c.a. Bi-213, depending on Ac-225 load on the generator |
| Specific Activity | |
| Radionuclidic Purity | U-233/Th-229 < 90 ppm (limit of detection); Ra-225 < 20 ppm (limit of detection) (Po-213, Pb-209 not considered) |
| Radiochemical Purity | >95% of radiolabelled compound (e.g. DOTATOC) |
| Chemical Purity | >99.98% |
| Identification | 440 keV gamma line present |
| Appearance | colourless eluate |
| pH | n.a.; depending on labelling conditions |
| Activity available | max. 1000 MBq reserved for clinical studies every two months, upon request |
| Availability | every two months, smaller amounts for preclinical studies upon request |
| Grade | GLP, n.c.a. |
| Other information | elution protocol is adaptable to the compound to be labelled, depending on the chelator and labeling protocol |