  A check of the eccentricity of the aluminised kapton straw tubes used in the
BTeV experiment is accomplished using X-ray tomography of the section of tubes
modules. 2 and 3-dimensional images of the single tubes and of the modules are
reconstructed and analysed. Preliminary results show that a precision better
than 40 $\mu$m can be reached on the measurement of the straw radii.
