Production routes of the alpha emitting <sup>149</sup>Tb for medical application
Bibliographic record
Abstract
Summary The partial alpha emitting lanthanide isotope 149 Tb seems to have a great potential in systemic radioimmuno therapy (RIT), especially when single cells in transit or circulation are targeted. The isotope 149 Tb has a half life of 4.118 h and decays by alpha emission (3.97 MeV, 17%) EC-process (76%) and β + -emission (7%). In this paper, we analyze the possible production routes: light- and heavy ion induced nuclear reactions and p-induced spallation. The excitation functions for light- and heavy ion induced reactions have been calculated using the ALICE91 code. The direct nuclear reaction 152 Gd ( p , 4 n ) 149 Tb was found to be the most promising production path. Alternatively, the indirect reaction 142 Nd ( 12 C, 5 n ) 149 Dy → 149 Tb seems to be much more suitable compared to the reaction on the mono-isotopic target element 141 Pr 12 C, 4 n ) 149 Tb. In this case, both, the production yield of 149 Tb and the radionuclidic purity are considerably lower, compared to the ( p , 4 n )-reaction. In preliminary experiments we produced 149 Tb via the indirect reaction Nd ( 12 C, 5 n ) 149 Dy → 149 Tb (108 MeV 12 C +6 ions and 1 particle-µA) at the U-200 heavy ion cyclotron at the FLNR of the JINR Dubna. From a 1.25 h irradiation of a 12 mg/cm 2 nat Nd 2 O 3 target, we obtained 2.7 MBq of 149 Tb (70 µCi) at 20 min EOB. This allows the conclusion, that a dedicated cyclotron equipped with a modern ECR-ion source, providing high ion currents would allow the continuous production of batches of the order of 10–20 GBq of 149 Tb for routine RI-therapy. The lower cross section of the spallation process can be compensated by using very thick targets. On-line mass separation technique provides high purity isotopically clean 149 Tb preparations, independently on the production route chosen. At the ISOLDE facility at CERN, we prepared batches of up to 500 MBq 149 Tb by combining on-line mass separation process followed by a cation exchange chromatography process using α-HIBA as eluent. The obtained 149 Tb preparations showed excellent behavior in labeling of chelated monoclonal antibodies.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".