First In Vivo and Phantom Imaging of Cyclotron-Produced <sup>133</sup>La as a Theranostic Radionuclide for <sup>225</sup>Ac and <sup>135</sup>La
Bibliographic record
Abstract
Theranostic isotope pairs have gained recent clinical interest as they can be labeled to the same tracer and applied for diagnostic and therapeutic purposes. The goals of this study were to A) investigate cyclotron production of clinically relevant 133La activities using natural and isotopically enriched barium target material, B) compare fundamental positron emission tomography (PET) phantom imaging characteristics of 133La with common PET radionuclides, and C) demonstrate in vivo preclinical PET tumor imaging using 133La-PSMA-I&T. Methods:133La was produced on a 24 MeV cyclotron using an aluminum-indium sealed target with 150-200 mg of isotopically enriched 135BaCO3, natBaCO3, and natBa metal. A NEPTIS Mosaic-LC performed Ba/La separation. DOTA, PSMA-I&T, and macropa were radiolabeled with 133La. Derenzo and National Electrical Manufacturers Association (NEMA) phantom imaging was performed with 133La, 132La, and 89Zr and compared with 18F, 68Ga, 44Sc, and 64Cu. In vivo preclinical imaging was performed with 133La-PSMA-I&T in LNCaP tumor-bearing mice. Results: Proton irradiations for 100 µA·min at 23.3 MeV yielded 214 ± 7 MBq 133La and 28 ± 1 MBq 135La using 135BaCO3, 59 ± 2 MBq 133La and 35 ± 1 MBq 135La using natBaCO3 and 81 ± 3 MBq 133La and 48 ± 1 MBq 135La using natBa metal. At 11.9 MeV, 135La yields were: 81 ± 2 MBq, 6.8 ± 0.4 MBq, and 9.9 ± 0.5 MBq for 135BaCO3, natBaCO3, and natBa metal. BaCO3 target material recovery was 95.4 ± 1.7%. NEMA and Derenzo phantom imaging demonstrated 133La PET spatial resolution, and scanner recovery coefficient were superior compared to 68Ga, 132La, and comparable to 89Zr. The apparent molar activity was 130 ± 15 GBq/μmol with DOTA, 73 ± 18 GBq/μmol with PSMA-I&T, and 206 ± 31 GBq/μmol with macropa. Preclinical PET imaging with 133La-PSMA-I&T provided high-resolution tumor visualization with a SUV60min of 0.97 ± 0.17. Conclusion: With high-yield 133La cyclotron production, recovery of BaCO3 target material, and superior fundamental imaging characteristics compared to 68Ga and 132La, 133La represents a promising radiometal candidate to provide high-resolution PET imaging as a PET/alpha therapy theranostic pair with 225Ac, or a PET/Auger electron therapy theranostic pair with 135La.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| 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) | 0.002 | 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 source (direct Gemma or distilled Codex), 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".