BasisSimulator.jl: Open-source polychromatic CT simulation with a GPU-portable reconstruction stack

GPU-native Julia framework for CT and photon-counting CT simulation, reconstruction, and quantitative spectral imaging. Provides distance-driven forward projection (with Siddon ray tracing as an alternative), polychromatic Beer-Lambert physics with vendor-realistic detector response (MC-derived LUTs for GE Gemstone scintillator and Siemens NAEOTOM Alpha CdTe), FDK, helical WFBP and hybrid iterative reconstruction, sinogram and image-domain beam-hardening correction, projection-domain dual-kVp and PCCT material decomposition (K-channel profile likelihood, Cong 2022), spectral denoising, and virtual monoenergetic imaging (VMI + Grant 2014 Mono+) — all dispatching transparently across CPU, Metal, CUDA, and ROCm via AcceleratedKernels.jl.