Integrating Confidence Maps and Visual Servoing for Needle Tracking in Robotic US-Guided Percutaneous Nephrolithotomy
Bibliographic record
Abstract
Ultrasound-guided percutaneous nephrolithotomy (PCNL) is a minimally invasive procedure to remove large kidney stones through an incision in the patient’s back. PCNL requires a high level of dexterity to steer a surgical tool while visualizing it using ultrasound images. A robotic system that controls the ultrasound probe to automatically image the tool would alleviate the surgeon’s cognitive workload and potentially lead to more accurate kidney access. We propose a novel algorithm that combines visual servoing and confidence maps to track the position of a manually steered needle using a robotically actuated ultrasound probe. The algorithm automatically adjusts the position of the ultrasound probe so that the same longitudinal portion of the needle shaft is visible in the image, while simultaneously ensuring acoustic contact between the ultrasound probe and the tissue over uneven surfaces. Unlike previous methods, where confidence maps were used for probe positioning with static targets, this paper introduces the first unified algorithm that optimizes image quality while tracking a moving tool. It ensures continuous probe-tissue contact on uneven surfaces and does not require prior knowledge of the needle’s trajectory or additional sensors. The algorithm, evaluated in phantom tissue and in a realistic kidney mannequin, shows an average tool tracking accuracy of 1.65 mm and 1.17 mm, respectively, confirming its ability to reliably track a manually inserted tool during PCNL.
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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 | 0.007 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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 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".