SU‐FF‐T‐218: Evaluation of the Exradin #a19 Ion Chamber for Reference Dosimetry in Megavoltage Photon Beams
Bibliographic record
Abstract
Purpose: The Exradin #a19 is a new design of reference‐class 0.6cc ion chamber that externally resembles the NE2571 Farmer chamber but internally is very similar to the well‐known Exradin #a12. This project involved the characterization of a single version of this chamber in high energy x‐rays. Method and Materials: The Exradin #a19 was compared against primary and reference standard ion chamber chambers at the National Research Council of Canada in a range of megavoltage photon beams (6–25 MV). Investigations looked at chamber settling, ion recombination and polarity, and determination of experimental k Q factors. Results: Chamber settling — the chamber response stabilizes very quickly (within 5 minutes), even after a large change in the polarizing voltage. i) The polarity correction was measured for 6 MV and 25 MV beams and found to be small (within 0.15% of unity). ii) The recombination correction showed a linear variation with the dose‐per‐pulse. The correction was similar to that of other Farmer‐type chambers. iii) Beam quality conversion factors were found to be closer to that of the NE2571 than the #a12, which is not consistent with the guidance given in TG‐51. However, with only a single chamber under investigation one cannot draw any definitive conclusions. Conclusion: An initial investigation of the Exradin #a19 Farmer‐type ion chamber suggests that it is fit for purpose for the calibration of megavoltage photon beams. Further work is in progress to evaluate this chamber in kilovoltage x‐ray and high‐energy electron beams.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".