Multifactorial study and kinetics of signal development in ferrous–methylthymol blue–gelatin gel dosimeters
Bibliographic record
Abstract
PURPOSE: To develop and characterize a ferrous-methylthymol blue-gelatin gel dosimeter with low optical background and appropriate additives for reduced rate of auto-oxidation and diffusion. METHODS: A mixed-level multifactorial design of experiments was used to test the effects of the concentrations of sulfuric acid, 5-nitro-1,10-phenanthroline (Nn), and glyoxal (Gx) on the background absorbance, dose sensitivity, and auto-oxidation of the tested gel dosimeter. The dosimetric properties of the proposed ferrous-methylthymol blue-gelatin dosimeter, doped with Nn and Gx, were compared with the undoped formulation and with ferrous-xylenol orange-gelatin gel dosimeters. Irradiations were performed in both small-scale cuvette samples and large 400-mL bulk samples. In addition to that, a new kinetic model for the signal development postirradiation was derived based on chemical principles and used for comparison of the different formulations. RESULTS: The new formulation showed a reduced auto-oxidation rate, while maintaining low background absorbance relative to the common ferrous-xylenol orange-gelatin gel dosimeter. Compared with undoped ferrous-xylenol orange or ferrous-methylthymol blue gels, the dose sensitivity of the new formulation is approximately 2 to 3 times lower, but remains clinically adequate. A previously unreported dose rate dependence of the dose sensitivity was observed, and a new kinetic model for the signal development postirradiation was used to investigate this effect. Similar dose rate dependences in gels containing either methylthymol blue or xylenol orange, with or without doping with Nn and Gx, were observed, suggesting that the low ferrous ammonium sulfate concentrations used in studied formulations were responsible for this effect. CONCLUSIONS: A multifactorial design of experiments and a new kinetic model for the signal development postirradiation were successfully employed to optimize the composition and characterize the properties of a new ferrous-methylthymol blue-gelatin gel dosimeter doped with 5-nitro-1,10-phenanthroline and glyoxal. Concrete recommendations were provided for precise dosimetry using the new formulation.
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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 | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 |
| 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".