Automatic needle localization in intraoperative 3D transvaginal ultrasound images for high-dose-rate interstitial gynecologic brachytherapy
Bibliographic record
Abstract
High-dose-rate interstitial gynecologic brachytherapy requires multiple needles to be inserted into the tumor and surrounding area, avoiding nearby healthy organs-at-risk (OARs), including the bladder and rectum. We propose the use of a 360° three-dimensional (3D) transvaginal ultrasound (TVUS) guidance system for visualization of needles and report on the implementation of two automatic needle segmentation algorithms to aid the localization of needles intraoperatively. Two-dimensional (2D) needle segmentation, allowing for immediate adjustments to needle trajectories to mitigate needle deflection and avoid OARs, was implemented in near real-time using a method based on a convolutional neural network with a U-Net architecture trained on a dataset of 2D ultrasound images from multiple applications with needle-like structures. In 18 unseen TVUS images, the median position difference [95% confidence interval] was 0.27 [0.20, 0.68] mm and mean angular difference was 0.50 [0.27, 1.16]° between manually and algorithmically segmented needles. Automatic needle segmentation was performed in 3D TVUS images using an algorithm leveraging the randomized 3D Hough transform. All needles were accurately localized in a proof-of-concept image with a median position difference of 0.79 [0.62, 0.93] mm and median angular difference of 0.46 [0.31, 0.62]°, when compared to manual segmentations. Further investigation into the robustness of the algorithm to complex cases containing large shadowing, air, or reverberation artefacts is ongoing. Intraoperative automatic needle segmentation in interstitial gynecologic brachytherapy has the potential to improve implant quality and provides the potential for 3D ultrasound to be used for treatment planning, eliminating the requirement for post-insertion CT scans.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".