Comparison of online adaptation strategies for magnetic resonance guided prostate radiation therapy
Bibliographic record
Abstract
Background and purpose: MR-guided adaptive radiation therapy allows for daily plan adaptation to account for anatomical changes. Two common strategies are adapt-to-position (ATP), involving re-optimization based on isocenter shifts, and adapt-to-shape (ATS), involving full recontouring and reoptimization. This study provides a dosimetric comparison of ATP and ATS using accumulated dose. Materials and methods: Dose accumulation was performed for 35 patients with prostate cancer treated on a 1.5 T MR-Linac. All patients received ATS-based treatment with either 30.0 Gy in 5 fractions (30.0/5) or 42.7 Gy in 7 fractions (42.7/7), using a 5 mm isotropic PTV margin. ATP plans were retrospectively simulated. For each fraction, dose was mapped to a reference image using deformable image registration and summed across fractions. Fractional and accumulated dose-volume histogram (DVH) metrics were compared between ATS and ATP and correlated with daily anatomical variation. Results: ATP and ATS achieved equivalent accumulated CTV D95 and D98 for both regimens. In the 30.0/5 cohort, small but statistically significant differences in OAR dose were observed: accumulated bladder D40 was 4 % lower for ATP (1.27 Gy; p = 0.0004), and rectum D50 was 1 % lower for ATP (0.40 Gy; p = 0.0008). Differences in rectum D1cc and bladder D5cc were not significant. In the 42.7/7 cohort, femur D5 was 3 % higher for ATP (0.83 Gy; p = 0.02); other differences were insignificant. Dosimetric differences across strategies correlated with interfraction motion. Conclusion: ATP and ATS provided equivalent target coverage. OAR differences were statistically significant in some cases but remained within clinical tolerances, suggesting minimal clinical impact.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".