Segmentation of aerated lung volume as a surrogate to assess the multifocal tumor spread in SPC-raf transgenic animal. Micro-CT showing the distinctive diffuse bilateral tumour growth (A). Seed points are placed manually in the aerated lung (B). Segmentation of the aerated lung is performed applying a region growing algorithm (C). Note that the lung areas consolidated by tumour are correctly excluded from the segmentation volume, no overspilling of segmentation volume into adjacent anatomical structures.