SegResNet.| Stage | Purpose | Input | Output |
|---|---|---|---|
| 1 (Localization) | Coarse kidney ROI extraction | 128³ downsampled volume | Binary kidney mask |
| 2 (Refinement) | Fine-grained kidney + tumor segmentation | Native-res crop + Stage 1 mask (3 channels) | Multi-class segmentation (kidney/tumor) |
DiceFocalLoss (γ=2.0) – mitigates class imbalance, emphasizes boundary accuracyAdamW + CosineAnnealingLRRandRotated, RandFlipd, RandGaussianNoise, RandGaussianSmooth, RandScaleIntensity, RandShiftIntensity| Stage | Best Epoch | Dice Score |
|---|---|---|
| 1 (Localization) | 66 | 0.87 |
| 2 (Refinement) | 110 | 0.66 |
Note: Stage 2 operates on high-resolution, tumor-sparse crops cause boundary precision is critical. The lower Dice reflects the inherent difficulty of fine-grained tumor delineation—not model failure.






