VSTRACH

vstrach - segment the trachea and airways

vstrach if=<tfile> of=<mask> [og=<v3d>] [sp=<seed>] [-v]

vstrach segments the airway lumen area from the whole lung CT scan. It invokes v3grow (3D region growing) and passes the appropriate parameters to v3grow. These parameters include the seed point location, region growing threshold, and the range of allowed volume. (See v3grow man page for more information)

The region growing threshold ([th=] in v3grow) is set to 120 (-904 HU).

The maximum allowed volume for the grown region ([M=] in v3grow) is set differently depending on the slice thickness of the CT scan input, as shown in the following:
1.25mm or less: M = 2000000 voxels
2.50mm or less: M = 1000000 voxels
greater than 2.50: M = 400000 voxels

To locate the seed point, the algorithm takes a 2D slice and finds the dark region that is relatively centered in horizontal dimension. Vstrach looks at the 2nd slice and takes the largest region’s center of mass as a seed point.

In case of invalid seed point (i.e. v3grow returns with error), v3grow is invoked once more with another seed point location. The new seed point is located by looking at the 45mm below the top-most slice of the scan.

Input must be a short image of a whole-lung CT scan.

v3grow

J. Lee