Sci‐Sat AM(1): Imaging‐02: Comparison between experimental measurements and Monte Carlo simulations for the off‐focal radiation in diagnostic x‐ray systems
Bibliographic record
Abstract
In a typical x-ray tube, off-focal radiation is mainly generated by the backscattered electrons that re-enter the anode outside the focal spot. In an earlier study, the EGSnrc/BEAMnrc system was modified to be able to properly transport the anode backscattered electrons, and to tally their subsequent generation of off-focal x-rays. In the current study, a diagnostic system and a recent digital mammography system are simulated using the modified BEAMnrc code, and the simulation results are compared with experimental measurements from the literature. Simulation results show excellent agreement with experimental measurements for the spectral shape of both the primary and the off-focal components, and also for the integral off-focal-to-primary ratio. The spectrum of the off-focal component at the patient plane is softer than the primary, which causes a slight softening in the overall spectrum. For a given configuration, the off-focal component increases with tube voltage because of the increased probability for off-focal x-rays to escape the anode self-filtration and the total filtration. This study validates our earlier implementation of off-focal radiation in EGSnrc/BEAMnrc, and provides a well-benchmarked tool that simulates x-ray tubes more realistically. The macro to add this feature to BEAMnrc is available from the authors.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".