Mathematical modeling and computer simulation of needle insertion into soft tissue
Fig 2
X-ray images of the cylindrical sample (diameter of 30 mm, height of 17 mm) of Sylgard 527 gel during needle insertion.
The images were acquired using X-ray C-arm General Electric 9900 apparatus located at The University of Western Australia Clinical Training and Evaluation Centre CTEC. (a) Calibration of the X-ray apparatus image acquisition system and image distortion evaluation using the X-ray opaque chessboard-like calibration pattern (the pattern was machined from a printed circuit board PCB). (b) X-ray image of the sample at the start of needle insertion. (c) X-ray image of the sample after the needle insertion to the depth of 8 mm. (d) Locally enlarged X-ray image after the needle insertion to the depth of 8 mm. Gel deformation in the area adjacent to the needle is clearly visible. U1 is the needle insertion depth (i.e. the needle tip displacement in relation to top sample surface) and U2 is the maximum deflection of the sample surface along the needle shaft. The deformation coefficient (see section 3.1 Kinematic approach) CD = U2/U1. For the experiment shown in this figure CD = U2/U1≈0.4.