Tham khảo tài liệu 'recent advances in biomedical engineering 2011 part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Towards a Robotic System for Minimally Invasive Breast Interventions 589 positioning the US probe guided by an image acquisition algorithm for automatic retrieval of the image of the target. This system continuously orients the transducer such that the 3D coordinates of the target are tracked in real-time. A novel sensorless technique for detecting contact state of US probe is also being investigated. The region in the image close to the edge where the US probe makes contact with the surface is used to detect the contact state of the US probe. This region is extracted from the US image and Otsu s method is used to estimate the greyscale threshold for the region. The threshold differential between contact and non contact states is used to infer the contact state of the US probe. The target manipulation technique presented in this paper will be integrated with the autonomous US imaging system to provide comprehensive robotic assistance during US guided breast interventional procedures. 6. Discussion PI control architecture has been presented in the paper for guiding a target towards the needle path. The performance of the controller is tested on phantoms with elastic property similar to that of breast tissue. We have demonstrated planar needle insertion as a proof-of-concept of a new control approach to target manipulation. As discussed in Section it does not limit the scope of our results. Results show that PI controlled robotic fingers can be used to efficiently position a target inline with needle during insertion. The proposed technique of guiding breast interventions can increase the success rate of the procedure. The entire procedure is predicted to be fast making it clinically viable. Since the needle is not steered inside the breast tissue damage is also minimized. Additionally since multiple insertions are not required the proposed technique will likely reduce clinician fatigue and patient discomfort and improve the structural integrity of the tissue .
