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Shape determination during needle insertion With curvature measurements

The determination of a flexible needle shape during the insertion is an important issue in minimally invasive surgery techniques. This is especially critical when considering conventional surgery procedures where a surgeon usually determines how to proceed needle insertion further based on the current needle trajectory inserted into tissue during biopsy and removal of malignant tissues in the body. In this paper, we propose a new method to determine the shape of a needle that is being inserted, together with the curvature measurement data obtained by fiber Bragg gratings (FBG) sensors inside the needle. This approach can be particularly advantageous to the situations where visual guidance (such as by ultrasound probes) is not easily applicable. The description of a needle shape is based on the elastic rod theory and Lie-group-theoretic approach. We also present the comparison between two different calibration methods, which have an impact on the quality of the results of the proposed method. In order to verify the proposed method, needle trajectories by the model are compared with experimental data obtained by image analysis, which in turn emphasizes the capability of the proposed method.