[Examining the accuracy of mechanical stiffness of the C-arm in navigation procedures].

During x-ray based navigation a number of errors causes distortions in the output image. These errors lead to a fail position of the surgical instrument relative to the patients anatomy. To minimize these influences and to develop dewarping techniques an exact error source identification is necessary. This paper examines the mechanical shift of the x-ray source relative to the image intensifier. Therefore three measurement methods will be used: an optical tracking system, a x-ray opaque probe and the integrated laser cross of the C-arm. The results of this examination show a notable shift of the C-arm geometry. However, no hysteresis effects could be found.