Neutron contamination of 10 MV X-rays: its relevance to treatment room door and maze design
Bibliographic record
Abstract
10 MV X-rays produced by linear accelerators are commonly used in radiotherapy. This paper demonstrates that neutron leakage cannot be neglected at 10 MV when direct access doors are used or when short mazes, typically less than 7 m in length, are employed. Measurements and calculations were made in terms of the operational quantities and personal and ambient dose equivalents, and the use of neutron fluence or contentious issues, such as effective dose and radiation weighting factors, were avoided. Neutron leakage from the head of an Elekta Precise linear accelerator was measured and compared with published data. The neutron protection afforded by a direct access door was considered and the use of borated polyethylene to remove thermal neutrons was found to be unnecessary. Extensive measurements were made in two treatment room mazes using survey meters of the Andersson-Braun and Leake type. Acceptable agreement was found between the individual instrument readings and calculations. However, one meter unexpectedly appeared to both respond to photons and over-respond at high neutron dose rates.
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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 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".