One-step ultrasound-based high dose rate (HDR) prostate brachytherapy with dose escalation to the dominant intra-prostatic lesion.
Bibliographic record
Abstract
106 Background: To demonstrate feasibility of using high dose rate (HDR) brachytherapy to deliver 25% higher than prescription dose to the dominant intra-prostatic lesion (DIL) as defined on multi-parametric MRI for intermediate and high risk prostate cancer. Methods: Twenty six patients with predominantly unilateral disease consented to a University Ethics-approved phase II study of selective dose escalation. HDR brachytherapy was performed in weeks 1 and 3 of treatment, each delivering one fraction of 10 Gy to the whole prostate. External beam consisted of 46Gy/23 fractions starting 3 days after the first HDR fraction.T2 FSE images were obtained using 1.5T endorectal MRI in transverse, sagittal and coronal planes followed by Dynamic Contrast Enhancement after injection of gadolinium. Apparent Diffusion Coefficient maps were calculated. The DIL was contoured on the MRI and, following image registration, transposed to the preoperative TRUS performed in the treatment position. Intra-operative TRUS with source-delivery catheters in place was fused to the pre-op TRUS with the transposed DIL. The DIL was included in dose optimization criteria. Results: Twenty five of 26 patients had a visible DIL. Mean prostate percentage receiving the prescription dose (V100) was 98.2% (SD:1.1). Mean dose to 90% of the DIL (D90) was 13.2 Gy (SD: 1.7). DIL mean volume was 2.9 cc (SD:1.8) representing 9.5% (SD: 7.6) of the prostate volume. Coverage of the DIL was excellent with a median of 97% receiving the planned escalation of 25%. Established dose constraints to rectum and urethra were respected in all cases. The factor that limited DIL coverage was proximity to organs at risk. Peri-urethral location of the DIL limited coverage in five cases and two had a posterior DIL such that dose to the rectum limited escalation. However, these seven cases still achieved a mean DIL D90 of 12.2 Gy. Conclusions: Dose manipulation using US-planned HDR brachytherapy is readily achievable within the practice setting of a community cancer center. Dose escalation to the DIL to a mean of 132% of the prescribed dose for selected intermediate and high risk prostate cancer patients is feasible while respecting critical organ constraints. Further escalation is planned. Clinical trial information: NCT01605097.
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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 | 0.000 | 0.001 |
| 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) | 0.001 | 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 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".