1. A method for segmenting bone regions from Computed Tomography Angiography (CTA) volume data comprising the steps of: receiving grayscale CTA volume data, said CTA volume data containing bone regions and contrast agent filled vessels; automatically detecting and distinguishing between bone regions and contrast agent filled vessels in the CTA volume data; filtering noise from detected bone regions; and dilating the filtered detected bone regions to adjacent bones, wherein bone regions are detected by computing the following formula: γ=|∇f(x+r,y,z)|+|∇f(x−r,y,z)|−|∇f(x+r,y,z)+∇f(x−r,y,z)|, where f(x,y,z) is an intensity at spatial coordinate (x,y,z) and r is a resolution at which the bone regions are to be detected, and wherein a value of γ>τ is identified as an initial bone region prior to filtering and dilating, where τ is a targeted threshold value.