TH-E-BRB-01: Improving the Energy Dependence of GAFChromic Dosimetry Films at Low Energies
Bibliographic record
Abstract
Purpose: Several studies have investigated the energy dependence of GAFChromic dosimetry films and shown a 5% to 10% energy dependence for energies below 100 keV. The purpose of this work is to improve the energy dependence of GAFChromic films and develop a new prototype with more uniform energy response at low energies (less than 100keV) Methods: The energy dependence of three commercial GAFChromic films, EBT-1, EBT-2 and EBT-3, has been investigated by irradiating the films to 2 Gy (Dose to water) at different beam qualities (50 kVp to 60Co). Also, the extrinsic energy dependence of the films is investigated using DOSRZnrc user-code of the EGSnrcMP Monte Carlo Package, by determining ratio of dose to water to dose to the active volume of the film using beam spectra calculated from SpekCalc. This software generates a nominal x-ray spectrum based on input information on experimental HVL, tube potential and added filtration data. The investigation of the extrinsic energy response combined with experimental evaluation of the overall energy dependence of the film response should help us understand the physics behind the energy variation of the film response and help us in improving the energy dependence at low energies. Results: Current EBT film models show strong intrinsic energy dependence at low energies indicating low polymerization efficiency of the films active layer, which can be compensated for by boosting the dose to the active layer at those energies by the incorporation of moderate atomic number elements such as K, Cl, Al and Na into the active layer of the film and the careful adjustment of the mass percent of these elements and the configuration of the film. Conclusions: Improving the energy dependence is possible by careful adjustment of the composition and mass percent of the elements incorporated into the film active layer and film configuration. David Lewis is employed by Ashland Specialty Ingredients the manufacturer of Gafchromic radiochromic films
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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 | 0.000 | 0.001 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".