Open-source 2D multispectral forward and inverse solver of the radiative transfer equation - de Ternero AM; Sancho J; Villa M; Martín-Pérez A; Vazquez G; Cebrián PL; Rosa G; Suthradhar P; Chavarrías M; Juárez E; Sanz C (Medical Imaging 2012: Image Processing, 2025)