TH-AB-201-11: A Systematic Characterization of the Low Energy Response of Plastic Scintillation Detectors
Bibliographic record
Abstract
Purpose: To characterize the low energy behavior of scintillating material used in plastic scintillation detectors. Methods: Four plastic scintillation detectors (PSDs) were developed using three different scintillating material (BCF-10, BCF-12, BCF-60) and one scintillator-free fiber. The scintillators were 1 mm in diameter and 10 mm-long, coupled to a 15 meter long clear PMMA optical fiber. A photomultiplier tube was connected to this fiber to collect the scintillator's light signal. All fibers were covered by a light-tight polyethylene jacket. The PSDs were exposed to AAPM accredited low energy beam qualities ranging from 20 kVp to 250 kVp. Their response described the dose in polystyrene and was compared to the dose in air measured by a primary calibration chamber located at the beam exit. The mean energy and the spectral method were used to extract the effective mass energy-absorption coefficient using NIST database for each beam quality reference spectrum. Attenuation in air and in the fiber jacket were also considered. The scintillators expected response was compared to the experimental measurements and an energy-dependent correction factor was identified to account for low energy quenching occurring within the scintillators. Results: The clear optical fiber response was below 0.5% of the scintillator's light, which indicated that a negligible amount of fluorescence contamination was produced. The scintillators response increased by a factor 3.65 ± 0.07 between a 20 kVp and a 250 kVp beam. The correction factor varied with beam energy and remained above 84% for beam qualities of 30 kVp and above, but drops for very low energy (20 kVp) to about 77%. Conclusion: This work describes the PSD energy dependence to low energy beam qualities and identifies a correction factor related to low energy quenching. A detailed comprehension of intrinsic scintillator response is essential when designing accurate PSD dosimeters for radiology purposes. This work was supported in part by a NIH/NCI SBIR grant R44CA153824 and by grant # 435510 from the NSERC. JB is supported by a FQRNT doctoral research scholarchip and acknowledges partial support by the NSERC CREATE Medical Physics Research Training Network grant # 432290.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".