Electron and photon spread contributions to the radiological penumbra for small monoenergetic x-ray beam (≤2 MeV)
Bibliographic record
Abstract
Our team has previously published that submegavoltage photons could significantly improve the radiological penumbra for small size radiation fields. The present work uses Monte Carlo simulation to evaluate the contributions of secondary electrons and photon scatter to the penumbra region for various field sizes (5, 10, 20, and 40 mm in diameters) and for various monoenergetic photon beams (200, 400, 600, 800, 1000, and 2000 keV, and a standard 6 MV beam), minimizing geometrical and transmission penumbra. For field sizes less than 2 cm in diameter, photon scatter is negligible such that the secondary electrons are the main contributor to the radiological penumbra. Reducing the photon beam energy to the submegavoltage range reduces the range of secondary electrons and eventually improves the beam boundary sharpness. Provided that the geometrical penumbra and patient immobilization system are optimized, submegavoltage photon beams with effective photon energies in the 300 to 600 keV range, present significant advantages for multiple beam stereotactic irradiations of tumors less than 2 cm in diameter.
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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".