jiayangshi/lodochallenge_latent_diffusion

Latent Diffusion Model – LoDoChallenge (DM4CT)

This repository contains the pretrained latent-space diffusion model used in the
DM4CT: Benchmarking Diffusion Models for CT Reconstruction (ICLR 2026) benchmark.

🔗 Paper: https://openreview.net/forum?id=YE5scJekg5
🔗 Arxiv: https://arxiv.org/abs/2602.18589
🔗 Codebase: https://github.com/DM4CT/DM4CT

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🔬 Model Overview

This model learns a prior over CT reconstruction images in a compressed latent space using a denoising diffusion probabilistic model (DDPM).

Unlike the pixel diffusion model, diffusion is performed in the latent space of a pretrained autoencoder.

• Architecture:
  • VQ-VAE (image encoder/decoder)
  • 2D UNet operating in latent space
• Input resolution (image space): 512 × 512
• Latent resolution: (insert latent size, e.g., 64 × 64)
• Channels: 1 (grayscale CT slice)
• Training objective: ε-prediction (standard DDPM formulation)
• Noise schedule: Linear beta schedule
• Training dataset: Low Dose Grand Challenge (LoDoChallenge)
• Intensity normalization: Rescaled to (-1, 1)

The diffusion model operates purely in latent space and relies on the autoencoder for encoding and decoding.

This model is intended to be combined with data-consistency correction for CT reconstruction.

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📊 Dataset: Low Dose Grand Challenge

Source:
https://www.aapm.org/grandchallenge/lowdosect/

Preprocessing steps:

• Train/test split
• Rescale reconstructed slices to (-1, 1)
• No geometry information is embedded in the model

The model learns an unconditional latent prior over CT slices.

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🧠 Training Details

• Optimizer: AdamW
• Learning rate: 1e-4
• Batch size: (insert your batch size)
• Training steps: (insert number of steps)
• Hardware: NVIDIA A100 GPU

Training scripts:

• Latent diffusion: https://github.com/DM4CT/DM4CT/blob/main/train_latent.py
• Autoencoder training: (insert if separate)

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🚀 Usage

from diffusers import LDMPipeline

LDMPipeline = DiffusionPipeline.from_pretrained(
    "jiayangshi/lodochallenge_latent_diffusion"
)

pipeline.to("cuda")