Reality-based needle insertion simulation for haptic feedback in prostate brachytherapy

There is a strong need to improve the tools clinicians use for training in procedures such as prostate brachytherapy where the success rate is directly related to the clinician´s level of experience. Accurate haptic feedback is needed for developing improved surgical simulators and trainers for such procedures. In prostate brachytherapy, accurate needle placement of radioactive seeds in the prostate is crucial to the success of the surgery and to the quality of life of the patient. Therefore, a trainer or simulator for this and other types of needle insertion tasks require an accurate reality-based quantification and model of the needle and soft tissue interaction. To achieve this, we utilize the X-ray images produced by a dual C-arm fluoroscope setup during a needle insertion task to obtain parameters needed for accurate modeling of soft tissue and needle interactions. The needle and implanted markers in the tissue are tracked during the insertion and withdrawal of the needle at speeds of 1.016 mm/sec, 12.7 mm/sec and 25.4 mm/sec. Both image and force data are utilized to determine important parameters such as the local effective modulus during puncture and the approximate cutting force for soft tissue samples. A finite element model was built using the data to model needle puncture of tissue