1. A method for detecting airways within an original image of a chest, comprising: generating a segmented image of an airway from said original image using region growing; generating a candidate mask; and iteratively detecting additional airways in said original image by performing a plurality of iterations, each iteration comprising: detecting airway candidates by applying a three dimensional morphological operator to said original image to obtain a resulting image of said airway candidates wherein a size of the 3D morphological operator varies with each iteration; applying said candidate mask to said resulting image to generate a masked resulting image; and updating said segmented image of said airway using said masked resulting image to detect said airways.