Poster — Thur Eve — 61: A dosimetric comparison between single‐arc and double‐arc prostate VMAT plans
Bibliographic record
Abstract
This study compared the dosimetry between prostate plans using the single‐arc and double‐arc technique in volumetric modulated arc therapy (VMAT). Single‐arc and double‐arc prostate VMAT plans were created in five patients with prostate volumes ranging from 39.0–68.1 cm3. 6 MV photon beams generated by a Varian 21EX linac with 120‐leaf multileaf collimator, and prescription dose of 78 Gy with 39 fractions were used. Dose‐volume histograms of the target and critical organs, dose criteria such as the planning target volume (PTV) D99%, rectum D30% and rectum D50%, and dose profiles along the anterior‐posterior and lateral directions crossing the isocenter were determined using the Eclipse treatment planning system with RapidArc optimization. It is found that the double‐arc technique provided a better PTV coverage and rectal sparing compared to the single‐arc for all patients. For dose profiles crossing the isocenter, it is seen that the dose in the anterior‐posterior direction was shifted to the lateral, when the single‐arc technique was replaced by the double‐arc. This dosimetric change made the dose in the rectal position shift laterally to the femoral head, resulting in a lower rectal dose. The calculated monitor units (MUs) were 471–600 for the single‐arc plans and 587–730 for the double‐arc. Although the double‐arc plans on average required more MUs of about 20%, and almost twice the treatment time compared to the single‐arc, it is worthwhile to be considered particularly in some cases, where the dose criteria are difficult to achieve using the single‐arc technique.
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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) | 0.000 | 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 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.014 | 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".