Field output correction factors using a scintillation detector
Bibliographic record
Abstract
Abstract Background As small radiation fields play an ever‐increasing role in radiation therapy, accurate dosimetry of these fields becomes critical to ensure high quality dose calculation and treatment optimization. Despite the availability of several small volume dose detectors, small field dosimetry remains challenging. The PRB‐0002, a new plastic scintillation detector part of the Hyperscint RP‐200 dosimetric platform from Medscint, that requires only minimal corrections can potentially facilitate small field measurements. Purpose The main objective of this work is to adapt small field formalism to plastic scintillation dosimetry using both Monte Carlo (MC) simulations and measurements. The secondary objective is to use the fully characterized PRB‐0002 for accurate and precise measurements of field output correction factors and compare those measurements with that from other small field detectors. Methods Our work is based on IAEA TRS‐483 report. EGSnrc MC simulations of the PRB‐0002 were conducted to determine the impact of detector composition, surrounding materials, dose averaging within the sensitive volume as well as ionization quenching. From these simulations, the field output correction factors of PRB‐0002 were determined. Then, by experimental comparisons, field output correction factors for 2 solid state detectors and 3 small volume ion chambers have been determined. Results With PRB‐0002, the material composition factor is well balanced with the ionization quenching making the field output correction factor near unity. For fields between 0.6 0.6 and 30 30 , the field output correction factors of the PRB‐0002 were between 1.002 and 0.999 with a total uncertainty of 0.5%. Analysis of the uncertainty budget showed that, using PRB‐0002 for measuring output factors an overall uncertainty of 0.59% can be achieved for a 1 1 field size. Conclusions With field output correction factors close to unity for a wide range of field sizes, the PRB‐0002 is a near‐ideal detector for small field dosimetry. Furthermore, it can be used to experimentally determine the field output correction factors of other dosimeters with great accuracy.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".