Design of an Adjustable Anti-Scatter Grid for Tomosynthesis Mammography
Bibliographic record
Abstract
CancerCare Manitoba is preparing to transition its facilities from film mammography to full-field digital mammography. During this process, CancerCare Manitoba will evaluate the incorporation of tomosynthesis mammography into their breast cancer detection regime. CancerCare Manitoba's Division of Medical Physics is responsible for procuring and maintaining medical devices for the organization. Our team has been tasked with the conceptualization of an anti-scatter device that can be adapted to operate in commercially available tomosynthesis scanners. As the Department of Medical Physics has not yet selected a scanner for purchase, they requested our anti-scatter solutions be presented as general concepts. Anti-scatter devices eliminate X-rays that are scattered in breast tissue, while permitting primary X-rays to pass through. This filtration process dramatically improves the contrast of the X-ray image, but increases the radiation dose to the patient. The dose increase required to produce an X-ray image with a grid is called a Bucky Factor and the scatter reduction is captured in a contrast improvement factor. Together, these factors quantify grid performance and guide the selection of an anti-scatter device. Estimating the Bucky factor and contrast improvement factor is not within the scope of this report, but after close consultation with our client's representative, we selected three designs to present for CancerCare Manitoba's consideration. These designs have several common elements including the dimensions of the grid, the X-ray attenuation material (lead), and a Bucky. The Bucky is a device that moves anti-scatter grids back and forth perpendicular to the gridline alignment. This movement reduces the shadow of gridlines on the X-ray detector, improving the final image. Our first design is a reoriented permutation of traditional focused anti-scatter grids. In our design, the grid's attenuation lines are aligned with the moving X-ray source's path, reducing scatter while permitting primary X-rays to hit the detector. The gridlines are to be constructed using an additive lithographic process, and the grid is expected to cost $5,000. The second anti-scatter design presented in this report is a flexible adaptation of our reoriented grid. Since the X-ray source moves along an arc to preserve its distance from the breast […]
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| 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".