Response of CZT pixels to parallel and oblique x rays
Bibliographic record
Abstract
CZT detectors are gaining popularity in the medical field. A numerical study of the response of CZT detector pixels to parallel and oblique x rays was conducted. The average k-fluorescence energy generated in a given pixel is 26.0 keV. It is assumed that such x rays travel a mean free path mfp = 0.161 mm in CZT before being absorbed. For applications in nuclear medicine, incident 140 keV photons were used. Each pixel had an area 1.5 mm x 3.3 mm and thickness 5 mm. The spacing between pixels was Δ = 0:3 mm and since Δ >mfp, the model predicts no cross talk between pixels. For parallel photons, the probability of escape is PFesc = 4:0% and the quantum efficiency η = 0:88. Next consider an isotropic source located at a distance 20 cm from the detector plane. For incident angles of 0° to 23° η varied from 0.88 to 0.5 and the fluorescence escape from 3.8 % to 2.0 %. For breast CT applications a typical pixel size is 0.2 mm by 0.2 mm and thickness 0.75 mm. The corresponding values for photons of energy 60 keV are as follows: (i) parallel η = 0:94, PFesc = 30%, oblique η = 0:94, PFesc = 30% at 0°; η = 0:55, PFesc = 18% at 23°. This work provides some quantification of the response of CZT detector pixels to x rays. Cross talk would need to be examined for the breast CT detector.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".