The architectural impact of single photon transmission measurements on full ring 3-D positron tomography
Bibliographic record
Abstract
For the full potential of high resolution (2 to 4 mm) full ring 3-D positron emission tomography (PET) to be realized, reductions in both scan time and noise for measured attenuation correction must be provided. Recent advancements in 3-D PET transmission measurements have been demonstrated using a point source and collecting single photon gamma radiation. Greater than an order of magnitude increase in counting statistics for 3-D acquisitions is possible over traditional dual photon techniques such as rotating rods. Usable single photon transmission scans as short as 2 minutes are practical. Such short scans will have reduced noise due to counting rates in excess of 2.5 M events/sec. Acquiring single photon transmission data in full ring 3-D PET requires several architectural additions to the tomograph. Additions include: 1) a "place holding" mode for the coincidence processor, 2) real-time single photon line of response rebinning electronics, 3) a liquid drive for moving a 4 mCi /sup 137/Cs point source at 1 metre/sec around the field of view, and 4) a fiber-optic detector system for tracking the point source position and speed. Initial implementation of these changes supports a first-of-its-kind 82 cm diameter, 23 cm axial length high resolution full ring 3-D PET tomograph.
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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 | 0.003 | 0.020 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".