“…The contrast between lungs and the surrounding healthy tissue in CT scans is evident and this fact explains why a significant number of segmentation approaches incorporate thresholding 2 nd Portuguese Meeting in Bioengineering, February 2012 Portuguese chapter of IEEE EMBS Rectory of the University of Coimbra operations such as [4]- [6], among many others. In addition to thresholding approaches, other types of different segmentation methods can be defined [7], such as: region growing approaches [3] which extract regions according to predefined criteria, classifiers [8], clustering approaches, [9] Markov random field models [10], artificial neural networks [11], [12], deformable models [13] and atlas guided approaches [14]. In this paper we propose a method for the delineation of the lungs based on an automatic threshold technique.…”