Organizations: School of Medical Science and Technology, Indian Institute of Technology Kharagpur, Kharagpur 721302 India · Computer Science Department, Arizona State University, Tempe, Arizona 85287 USA · Narayana Hospital, Kolkata 700107 India
We present a real-time, hybrid framework for occlusion handling and depth-aware tracking in minimally invasive surgeries (MIS). Occlusions caused by surgical instruments often obscure the region of interest (ROI), affecting surgical precision. To address this, our approach integrates enhanced You Only Look Once (YOLO) based detection, Particle Filtering (PF), and monocular depth estimation using Multiple Depth Estimation Accuracy with Single Network (MiDaS). Occlusion is detected using a distance-based threshold between instruments and ROI. Experimental results demonstrate robust instrument detection with a confidence score of 0.85, effective occlusion event handling, and accurate depth prediction with an MAE of 0.34 cm and RMSE of 0.53 cm. Independent phantom-based validation against stereo depth measurements yielded an MAE of 0.65 cm and RMSE of 0.66 cm. The framework further achieved an occlusion detection accuracy of 81.95% while maintaining real-time performance at 38.7 FPS. Preliminary surgeon feedback indicates that the proposed visualization framework is clinically relevant and holds promise for future intraoperative image-guided navigation and decision support in MIS.
Figures & tables
Fig. 1: The workflow of the proposed system: (a) Surgical video frames for pre-processing. (b) Integration of particle filtering for surgical tool and ROI detection. (c) Monocular depth estimation using the MiDaS model. (d) Real-time visualization of the surgical scene.
Fig. 2: Representative frames of different surgical actions acquired from robot-assisted cholecystectomies (a–d) with corresponding relative depth maps (e–h).
Fig. 3: Representative surgical frames illustrating real-time instrument tracking and occlusion handling at (a) t, (b) t+3s with a text-based alert, (c) t+5s with a color-coded bounding box, and (d) t+9s with depth-aware color-coded cues, where the bounding box changes from green (safe) to yellow (partial occlusion) and red (complete occlusion).
Class
Precision
Recall
mAP 50
mAP 50-95
Overall
0.793
0.867
0.894
0.713
ROI
0.505
0.319
0.356
0.102
AtraumaticGrasper_Head
0.894
0.913
0.959
0.760
AtraumaticGrasper_Body
0.858
0.900
0.949
0.757
Electrichook
0.925
0.971
0.984
0.862
CurvedAtraumaticGrasper_Head
0.808
0.898
0.908
0.718
TABLE I: Class-wise detection performance of the proposed YOLOv10 detector on the extended hSDB dataset.
Training Dataset
mAP 50 (%)
mAP 50-95 (%)
Original (17 classes)
75.47±3.16
57.31±2.12
Extended (17 classes + ROI)
71.01±2.62
53.30±2.20
TABLE II: Five-fold cross-validation performance of the YOLOv10 detector on the hSDB dataset.
Fig. 4: Depth mapping and validation during robotic surgery: (a) Reference surgical scene with paper scale, (b) Corresponding depth map with marked coordinates, (c) The linear regression plot of real and predicted depth values.
Method
Backbone
Configuration
mAP 50-95 (%)
Faster R-CNN
ResNet50
FPN
20.2
ResNet50
FPN + OHEM
20.1
ResNet50
FPN + Double Head
22.9
ResNet101
FPN
22.8
ResNeXt101-32 × 4d
FPN
24.1
ResNeXt101-64 × 4d
FPN
24.9
TABLE III: Comparison of object detection performance with SOTA methods on the hSDB dataset.
Method
Motion Model
Appearance
Monocular
Depth-aware
Multi-object
Real-time
Association
Depth
Occlusion Reasoning
Tracking
Suitable
SORT [ 18 ]
Kalman Filter
×
×
×
✓
✓
DeepSORT [ 19 ]
Kalman + Deep Re-ID
✓
×
×
✓
Limited
ByteTrack [ 20 ]
IoU-based Association
×
×
×
✓
✓
PF + MiDaS (Proposed)
Particle Filter
×
✓
✓
✓
✓
TABLE IV: Qualitative comparison of representative tracking and occlusion handling approaches.
Configuration
tIoU
Mean Confidence
Latency (ms)
FPS
YOLOv10
0.4079
0.6680
18.3
54.6
YOLOv10 + PF
0.6134
0.8339
18.6
53.8
TABLE V: Ablation Study evaluating the contribution of Particle Filtering.
Fig. 5: Independent phantom-based validation of monocular depth estimation using the OAK-D Lite camera (N = 15): (a) Experimental setup showing the phantom and imaging configuration, (b) Acquired depth map overlaid on the corresponding RGB image, with the automatically detected ArUco marker (51.6 cm), (c) Corresponding MiDaS-predicted depth map from the captured RGB image, yielding an estimated depth of 50.96 cm (absolute error = 0.64 cm), and (d) Bland–Altman agreement analysis between MiDaS-predicted depths and OAK-D Lite reference measurements across all validation samples.
Fig. 6: Runtime distribution and throughput comparison across pipeline operating modes: (a) Individual module latency breakdown for full sequential processing ( 70.0 ms/frame); (b) Latency and frame rate comparison across Sequential ( 14.3 FPS), Interleaved Depth Sampling ( 38.7 FPS), and Tracking-Only ( 56.1 FPS) operational modes against the 30 FPS real-time target ( 33.3 ms) and 100 ms clinical threshold.
Fig. 7: Violin plots of (a) Occlusion frequency and years of surgical experience, (b) Surgeons’ preference of occlusion alerts.