Poster - Thurs Eve-37: Energy and irradiation modality independence of calibration coefficients for water equivalent plastic scintillation detectors in the megavoltage range
Bibliographic record
Abstract
PURPOSE: To demonstrate that the independence of the calibration coefficients of plastic scintillation detector (PSD) for both photon and electron beams in the megavoltage energy range. METHOD AND MATERIALS: The PSD consists in a small 1 mm diameter and 2 mm long plastic scintillating fiber made of a polystyrene core (BCF-12, Saint-Gobain, inc.). The scintillator was coupled to a 2 meters long non-scintillating plastic optical fiber and a color CCD camera (Apogee instruments inc.) was used as photodetector. The calibration coefficients of the PSD where extracted for 6 MV, 23 MV photon beams and 9,12,15 and 18 MeV electron beams using a Farmer ionization chamber (Exradin). Complete removal of the Cerenkov radiation produced in the optical fiber was performed with a chromatic discrimination technique using the blue and green channel of the CCD camera. All measurements were performed according to the recommendations of the AAPM TG-51 protocol for clinical dosimetry. RESULTS: The PSD exhibits a maximum deviation of less than 1.7 % (about the mean) of its calibration coefficients over the measured energy range for both irradiation modalities. CONCLUSION: The energy independence of the calibration coefficients for PSD was demonstrated experimentally for the first time for both photons and electrons. PSDs have the potential to simplify and improve accuracy of dose measurements in clinical situations where photons and electrons are both present in the beam such as electron contamination in photon beams or bremsstrahlung contaminated electron beams.
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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 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.019 | 0.007 |
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".