Investigation of the energy response of EBT-2 GAFCHROMIC⢠film model
Bibliographic record
Abstract
The aim of this project is to quantify the energy response of the existing EBT-2 model GAFCHROMICTM film and investigate for the eventual possible chemical compositions with improved energy response. In this work, the overall energy dependence of the EBT-2 model GAFCHROMICTM film is quantized through intrinsic and absorbed dose energy response. Absorbed dose energy response is studied by calculating dose to film sensitive layer and dose to water using DOSRZnrc of EGSnrcMP Monte Carlo user-code. The film was simulated inside a large body of solid water for megavoltage beams, while at kilovoltage energies the film was modeled in air. The simulations were repeated to score the dose to water for megavoltage and air kerma for kilo-voltage beams, respectively. The intrinsic energy response is quantified through a measurement of total energy response divided by the Monte Carlo calculated absorbed dose energy response. The measurements consisted of delivering an exact dose of 2 Gy to the sensitive layer of the film at orthovoltage energies (50 kVp, 120 kVp, and 180 kVp), 192Ir and 60Co beam. AAPM TG-51 and TG-61 reports were used to determine the dose-to-water and air-kerma in air in megavoltage and orthovoltage beams, respectively, while Monte Carlo simulated corrections were used to convert these results to the desired dose to the sensitive layer of the film. For EBT-2 model GAFCHROMICTM film, the overall energy dependence was found to vary by 39 % in the effective energy range from 24 keV to 1.25 MeV (for 60Co beam). It was determined that intrinsic (LET-dependent) energy dependence also plays an important role in the total energy dependence of EBT-2 model GAFCHROMICTM film and cannot be ignored.The absorbed dose energy dependence was also studied for a wide variety of film active layer compositions in a 10 keV-100 keV energy range as well as at 60Co using Monte Carlo simulations. The composition of the film active layer was varied according to physical limits set by the manufacturer. High atomic number elements (chlorine and bromine) were found to affect absorbed dose response drastically. Addition of bromine was found to affect film's response in the 40-50 keV region, while chlorine affected the entire region below 100 keV. Through numerical optimization of the composition of the active layer, it was thus possible to reduce the absorbed dose energy dependence and suggest new compositions with absorbed dose energy dependence variation of 4 % in the effective energy range of 28 keV to 1.25 MeV (for 60Co beam)
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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 | 0.000 |
| 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 | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".