Chemical properties
Tb-149 is a radiolanthanide, most often in trivalent state and chemically very similar to lutetium. The ionic radius of Tb3+ is 92 pm, i.e. just 7% larger than Lu3+, which explains that macrocyclic chelators suitable for Lu-177 can be directly employed for Tb-149 too, in particular DOTA.
Nuclear properties
Tb-149 decays with a half-life of 4.118(25) hours by 16.7% ɑ decay (3967 keV ɑ) to Eu-145 (T1/2=5.9 d). Moreover, Tb-149 decays by β+ decay (7.1(3)%) and electron capture (76.2%) to Gd-149 (T1/2=5.9 d). It emits a medium energy positron spectrum with 730 keV average energy and 2450 keV maximum energy.
Moreover, Tb-149 emits γ-rays at 165.0 keV (26.4%), 352.2 keV (29.4%), 388.6 keV (18.4%), 652.1 keV (16.2%), 853.4 keV (15.5%), etc.
The mean ɑ energy emitted per decay is 662 keV, the mean ɑ recoil energy 18 keV, the mean electron energy emitted per decay is 84 keV and the mean photon energy per decay is 1286 keV .
Production
Tb-149 is produced by high energy proton induced spallation of tantalum targets at the production facility MEDICIS at CERN. An off-line mass separation is performed at MEDICIS at CERN. The mass-separated ions are implanted into a solid matrix, e.g. an Al, Zn or NaCl layer on a noble metal backing. The implanted layer can be dissolved and used for an additional radiochemical separation to obtain optimum radionuclidic purity by removing the pseudo-isobars Ce-133, Ce-133m, La-133 that are mass-separated as oxide ions on mass 149.
Distribution
Tb-149 implanted into a solid matrix will be shipped from MEDICIS (CERN, Geneva, Switzerland). To minimize decay losses during shipping, experiments with Tb-149 are best performed at the medical facility AGORA (CHUV, Lausanne, Switzerland).
Examples of use
| Parameter | Specifications |
|---|---|
| Production route | Ta(p,spallation) |
| Daughter | Decays to Gd-149 (T1/2=9.3 d, 15 mBq per 1 Bq Tb-149) and Eu-145 (T1/2=5.9 d, 4.8 mBq per 1 Bq Tb-149): 16.7% α, 7.1% β+, 76.2% EC |
| Half-life | 4.12 h |
| Processing | Off-line mass separation |
| Primary Container | |
| Product Grade | n.c.a. |
| Physical Form | Solid |
| Chemical Form | Implanted in solid layer |
| Radioactive Concentration (gamma spectrometry) | n.a. |
| Appearance | n.a. |
| Radionuclide identification (gamma spectrometry) | 165 keV, 352 keV and 389 keV gamma lines present |
| Radionuclidic Purity (gamma spectrometry) | n.a. |
| Chemical purity (ICP-OES) | n.a. |
| Molar activity (ICP-OES) | n.a. |
| Apparent Molar Activity | n.a. |
| Microbiological quality | n.a. |
| Bacterial endotoxin | n.a. |
| pH (pH strips) | n.a. |
| Additional information | |
| Activity available | t.b.d. (under commissioning), few times per year (planning in advance) |
| Activity limit for UN2910 (excepted package) shipment | 0.8 GBq in dry state or 80 MBq in liquid form |
| Other information | Implanted in Al, Zn or NaCl layer on Au foil |