CATNIP: An Open-Source Wave-Optics Simulation Framework for Multimodal X-ray Imaging

We present the Comprehensive Analysis Toolkit for Near-field Imaging and Phase-retrieval (CATNIP), a wave-optics framework for simulating near-field X-ray imaging and benchmarking multimodal retrieval algorithms. CATNIP supports PBI, GBI, SBI, and EI under the projection approximation, integrating three retrieval algorithms within complete simulation–reconstruction pipelines. Validation against theory and Geant4 shows strong agreement, with normalized root mean square errors typically below 10%. CATNIP runs locally with optional remote server integration, enabling both rapid prototyping and large-scale studies. It provides a computationally efficient alternative to Monte Carlo methods for the design, optimization, and evaluation of near-field X-ray imaging techniques.