Sci‐Thur AM: YIS – 01: New technologies for astatine‐211 targeted alpha therapy research
Bibliographic record
Abstract
Purpose: The short‐range, densely ionizing α‐particles emitted by 211At (t1/2=7.2h) are well suited for the treatment of diffuse microscopic disease, using cancer targeting biomolecules. 211At availability is limited by the rarity of α‐cyclotrons required for standard production. Image‐based dosimetry is also limited for 211At, which emits low intensity X‐rays. Our goal was to leverage state‐of‐the‐art infrastructure at TRIUMF to produce and evaluate two related isotopes, 211Rn (t1/2=14.6h, 73% decay to 211At) as a generator for 211At, and 209At (t1/2=5.4h, X‐ray/gamma‐ray emitter) as a novel 211At surrogate for preclinical imaging studies. Methods: Produced by spallation of uranium with 480 MeV protons, mass separated ion beams of short‐lived francium isotopes were implanted into NaCl targets where 211Rn or 209At were produced by radioactive decay, in situ. 211Rn was transferred to dodecane from which 211At was efficiently extracted and evaluated for clinical applicability. High energy SPECT/CT was evaluated for measuring 209At activity distributions in mice and phantoms. Results: Our small scale 211Rn/211At generator system provided high purity 211At samples. The methods are immediately scalable to the level of radioactivity required for in vivo experiments with 211At. 209At‐based high energy SPECT imaging was determined suitable for pursuing image‐based dosimetry in mouse tumour models. In the future, we will utilize quantitative 209At‐SPECT for image‐based dose calculations. Conclusion: These early studies provided a foundation for future endeavours with 211At‐based α‐therapy. Canada is now significantly closer to clinical targeted α‐therapy of cancer.
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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 | 0.002 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.058 | 0.032 |
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".