Sci‐Sat AM: Radiation Dosimetry and Practical Therapy Solutions ‐ 06: Investigation of an absorbed dose to water formalism for a miniature low‐energy x‐ray source
Bibliographic record
Abstract
Purpose: We present a formalism for calculating the absorbed dose to water from a miniature x‐ray source (The INTRABEAM system, Carl Zeiss), using a parallel‐plate ionization chamber calibrated in terms of air‐kerma. Monte Carlo calculations were performed to derive a chamber conversion factor (CQ) from reference air‐kerma to dose to water for the INTRABEAM. CQ was investigated as a function of depth in water, and compared with the manufacturer's reported value. The effect of chamber air cavity dimension tolerance was also investigated. Methods: Air‐kerma (Ak) from a reference beam was calculated using the EGSnrc user code cavity. Using egs_chamber, a model of a PTW 34013 parallel‐plate ionization chamber was created according to manufacturer specifications. The dose to the chamber air cavity (Dgas) was simulated both in‐air (with reference beam) and in‐water (with INTRABEAM source). Dose to a small water voxel (Dw) was also calculated. CQ was derived from these quantities. Results: CQ was found to vary by up to 15% (1.30 vs 1.11) between chamber dimension extremes. The agreement between chamber CQ was found to improve with increasing depth in water. However, in all cases investigated, CQ was larger than the manufacturer reported value of 1.054. Conclusions: Our results show that cavity dimension tolerance has a significant effect on CQ, with differences as large as 15%. In all cases considered, CQ was found to be larger than the reported value of 1.054. This suggests that the recommended calculation underestimates the dose to water.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 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".