TU‐D‐AUD C‐07: Electron Depth Dose Measurements Using a Plastic Scintillation Detector and a Parallel‐Plate Ionization Chamber
Bibliographic record
Abstract
Purpose: Plastic scintillation detectors (PSDs) have been shown not to require stopping power or perturbation corrections to measure absorbed dose in high energy electron beams. The purpose of this work is to compare the performance of ionization chambers and PSDs in precise measurements of electron beams. Method and Materials: Electron beam depth dose measurements were performed on a Varian Clinac iX for 6 and 18 MeV. The ionization chamber measurements were performed using a Roos (PTW) parallel plate ionization chamber. The ionization chamber measurements were converted to dose using stopping power ratios for realistic clinical beams. The scintillation dosimetry measurements were performed using a miniature water equivalent plastic scintillation detector (1.6 mm3). This detector is made out of a (1 mm diameter by 2 mm long) BCF‐12 scintillating fiber coupled to a color CCD camera. The Cerenkov radiation produced in the PSD was filtered by a chromatic discrimination technique. Results: The percentage depth dose of the Roos chamber measured at 6 and 18 MeV agree well with the scintillation detector depth dose from Dmax to the R50 depth. As the depth increases past R50, a gradual discrepancy appears between the curves provided by the 2 detectors at both energies. Past the practical range (Rp) and into the Bremsstrahlung tail, the percentage depth dose curve of the Roos does not agree with the plastic scintillation detector at both energies (20 % and 50 % difference at 6 and 18 MeV). Conclusion: The discrepancy between the detectors suggests that: 1) The stopping power ratios do not model properly the transition between electrons and photons at the Rp depth or 2) there may be an increase in Pwall with depth for the parallel plate chamber or 3) there is loss of water equivalence for the PSD at low electron energies.
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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 | 0.001 |
| 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 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".