Dear all,
In February we announced the KonfAI and IMPACT-Synth extensions. Here is what is new.
TotalSynth models
We released TotalSynth, pretrained models for synthetic CT from MRI and from CBCT, from the head to the pelvis (arXiv:2609.13838). They were trained on 1450 quality-controlled pairs of the SynthRAD2023 and SynthRAD2025 challenges plus four prostate cohorts, with the planning CT registered to each input by IMPACT-Reg. Three 5-fold families are available on Hugging Face:
| Model | Input | MAE (HU) | SSIM | PSNR (dB) |
|---|---|---|---|---|
| MRI-to-CT | MRI | 67.5 | 0.920 | 29.3 |
| CBCT-to-CT | CBCT | 53.6 | 0.939 | 32.1 |
| Unified | MRI or CBCT | 67.7 / 54.2 | 0.920 / 0.938 | 29.2 / 31.9 |
On an external whole-body Dixon MRI dataset (BIC-MAC), fine-tuning on 45 local cases brought the MAE from 100.9 to 62.2 HU. Each app ships its training configuration, so konfai-apps fine-tune starts from the released weights on your own pairs.
IMPACT-Synth
The extension runs these models on a loaded MRI or CBCT and checks the result:
- Synthesis: pick the model, the checkpoints to ensemble and the test-time augmentations, click Run. The sCT is loaded over the input, in HU. About 15 s per checkpoint on a 24 GB GPU.
- Evaluation with a reference CT: MAE map, PSNR, SSIM, and the Dice of TotalSegmentator structures on the sCT and on the CT.
- Evaluation without reference: uncertainty map from the ensemble and TTA spread, conformity map from the disagreement of the segmentations.
- Segmentation tab: TotalSegmentator, MRSegmentator and IMPACT-Seg on the input or on the sCT.
Video (2 min) and tutorial.
KonfAI
The generic extension runs any KonfAI App on the volumes of the scene. Since February: apps added from any Hugging Face repository or local folder, with per-checkpoint download; an Advanced dialog for patch size, batch size and the parameters an app exposes, saved as a local app if you want; remote servers (konfai-apps-server on a GPU machine, its GPUs and memory shown in the panel); live RAM and VRAM gauges; fine-tuning setup; a launcher for KonfAI Studio. ImpactSynth and ImpactReg are built on the same library and get all of it.
Three videos of about a minute: run a published app, quality assurance, apps and remote servers; tutorial.
Install
View → Extensions Manager → ImpactSynth or KonfAI (Slicer 5.10 or newer). PyTorch comes from the SlicerPyTorch extension; a GPU with 8 GB of VRAM is enough.
Feedback and requests for other models are welcome.
Valentin Boussot, Cédric Hémon
Boussot V. et al., TotalSynth: Robust Whole-Body Synthetic CT from MRI and CBCT, arXiv:2609.13838, 2026.
Boussot V., Dillenseger J.-L., KonfAI: A Modular and Fully Configurable Framework for Deep Learning in Medical Imaging, arXiv:2508.09823, 2025.