Po‐Poster ‐ 10: Influence of varying SSD on the penumbra and the mean square scattering angle for electron beams
Bibliographic record
Abstract
The objective of this study was to quantify how varying source to surface distance (SSD) for electron beam therapy affects the width of the penumbra at the surface of the patient and to determine the influence of the SSD on the mean square scattering angle at the base of the electron applicator, 〈θ2〉(0), for use in electron beam treatment planning. Penumbra values were extracted from profiles measured at the surface of a water phantom for SSDs spanning 103–116 cm for numerous combinations of beam energy and electron applicator. 〈θ2〉(0) was derived from the measured penumbra values. The width of the penumbra was shown to climb in a linear fashion with increasing SSD over the range of values investigated. It was also observed that the size of the electron cone exerted considerably more influence on the penumbra for a given SSD for lower beam energies than for higher beam energies. In the case of lower beam energies, the penumbra width for a given SSD rose in a very significant way with increasing applicator size. 〈θ2〉(0) demonstrated a decreasing trend as SSD was increased. This decline was more drastic for lower beam energies. For higher beam energies, 〈θ2〉(0) values tended to be quite similar, despite varying SSD.
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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 | 0.001 | 0.002 |
| 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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".