MRI validation of Post-Prostatectomy Radiotherapy Contouring
Bibliographic record
Abstract
Introduction: Level One Evidence has established the indications for, and importance of, adjuvant radiotherapy following radical prostatectomy. Several guidelines have addressed delineation of the prostate bed but with variable specification of the inferior border relative to the penile bulb or to the first CT slice distal to visible urine in the bladder neck. This work determines the correlation between the caudal aspect of the anastomosis shown by the tip of the urethrogram cone and MRI anatomy. Materials and Methods : Sixteen patients receiving adjuvant radiotherapy following prostatectomy underwent diagnostic MRI in addition to planning CT with Urethrogram. The CT Reference Slice, tip of urethrogram cone and superior aspect of penile bulb were delineated. Results: MRI clearly demonstrates the penile bulb but not the anastomosis. In these 16 patients, the tip of the urethrogram cone was a median 3.9 mm cranial to the penile bulb (range 0-10.3 mm). Conclusion: We show marked variability in the distance between penile bulb and the tip of the urethrogram cone. In all sixteen patients, placing the inferior border of the CTV 15mm cranial to the penile bulb would have failed to treat the caudal aspect of the anastomosis, a frequent site of local relapse, that cannot be reliably landmarked by any other anatomic structure. Individualizing the treatment volume to patient anatomy is the only way to ensure consistent coverage without treating a larger than necessary volume in many patients. We recommend the use of planning urethrogram to minimize the potential for geographic miss.
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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 | 0.003 | 0.010 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".