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Needle Steering in Soft Tissue

Haghighi, Payam | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44575 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Jahed, Mehran
  7. Abstract:
  8. Medical needle interventions are a common technique for accessing tissue structures.In these procedures, needles are used, for example, to extract biopsy samples, brachytherapy, and to insert drugs. In TRUS guided prostate brachytherapy application, Physicians used ulterasound imaging to steer the needle and insert radioactive seeds into cancerous tumors to irradiate surrounding tissue over several months. Prostate rotation, deformation, and unavailability of imaging data during part of the insertion path result in misplaced seeds. To overcome these problems, in this research, we modeled the prostate, its membrane and the surrounding fatty tissue as linearly elastic homogenous material, and used the FEM based algorithm to calculate the deformation of prostate and estimate the force distribution along the needle shaft during insertion. We then fully modeled the behavior of the nonflexible needle inside the soft tissue, and designed a model-based controller for steering of needle. This inverse dynamic controller is designed such that the needle will be asymptotically converges the target. Although the placement error can’t be zero in practice due to the nonhonomic behavior of the needle, but will be decreased by average of 92%. It is shown that the uncertainty in the tissue mechanical parameters dramatically affects the system performance. To handle this uncertainty, a novel H ¥ robust controller is proposed. First of all, we obtained the needle steering close-loop diagram, and then extracted the LFT structure. Numerical results are presented to illustrate the enhanced performance of the proposed methodology by an average of 55%
  9. Keywords:
  10. Robust Control ; Needle Steering ; Brachytherapy ; Finite Element Method ; Model Based Control ; Soft Tissues

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