Nasopharynx cancer, or nasopharyngeal carcinoma (NPC), is a tumor that originates in the nasopharynx, the uppermost region of the pharynx where the nasal passage and the throat join. It is a common disease occurring to ethnic Chinese people living in or emigrating from southern China; it is also the eighth most frequently occurred cancer among Singaporean men. Traditional posterior nasopharyngeal biopsy using a flexible nasal endoscope has the risks of abrasion and injury to the nasal mucosa and thus causing trauma to the patient. Therefore, the goal of this project is to develop a compact continuum tubular robotic system to achieve collision free nasopharyngeal biopsy.
Fig.1 Illustration of the proposed CTR for nasopharyngeal biopsy.
We developed a compact CTR which is 35 cm in total length, 10 cm in diameter, 2.15 kg in weight, and easy to be integrated with a robotic arm to perform more complicated operations.
Fig.2 The proposed continuum tubular robot
Fig.3 Compact and light weight CTR integrated with a positioning arm for
better conducting surgery
We also developed a 3D printed biopsy needle to equip our robot for transnasal biopsy procedure.
Fig.4 3D printed biopsy needle for transnasal biopsy
The workspace of the robot was analyzed to determine optimized tube parameters.
Fig.5 Workspace comparison for 3-DOF CTR with three initial configurations.
Top: all the outstretched part of the inner tube exposes; Middle: the outstretched part of the inner tube is partially covered by the outer tube; Bottom: the outstretched part of the inner tube is totally covered by the outer tube.
Further more, by using an electromagnetic tracking system, we are able to build a navigation system with shape reconstruction for the tubes.
Fig.6 Shape reconstruction using 3-order Bézier curve fitting
Fig.7 Sensing by EM tracker
Fig.8 Navigation interface
Three groups of experiments were carried out. The first group is to tele-operate the robot to follow a linear path and a circular path. We found that the path following accuracy was about 2 mm.
Fig.9 Tele-operating the robot to follow a linear path and a circular path
Fig.10 Accuracy of the robot following the predefined paths
The second group is to validate the shape reconstruction algorithm. The accuracy of the results is about 1 mm.
Fig.11 Reconstruction setup
Fig.12 Reconstruction error
In the last group of experiments, the robot was tested in a biopsy procedure on a cadaver. The feasibility of the proposed robotic system was validated.
Fig.13 Cadaver experiment setup
Fig.14 Cadaver experiment process
Research Fellow: Liao Wu
PhD Student: Keyu Wu
FYP Student: Li Ting Lynette Teo
Intern Student: Jan Feiling and Xin Liu
Project Investigator: Hongliang Ren
 Liao Wu, Shuang Song, Keyu Wu, Chwee Ming Lim, Hongliang Ren. Development of a compact continuum tubular robotic system for nasopharyngeal biopsy. Medical & Biological Engineering & Computing. 2016.
 Keyu Wu, Liao Wu, Hongliang Ren. Motion planning of continuum tubular robots based on features extracted from statistical atlas. In: Proceedings of 2015 IEEE International Conference on Intelligent Robots and Systems (IROS 2015).
 Keyu Wu, Liao Wu, Chwee Ming Lim, Hongliang Ren. Model-free image guidance for intelligent tubular robots with pre-clinical feasibility study: towards minimally invasive trans-orifice surgery. In: Proceedings of 2015 IEEE International Conference on Information and Automation (ICIA 2015). ( best paper finalist)
 Benedict Tan, Liao Wu, Hongliang Ren. Prototype development of a handheld tubular curvilinear robot for minimally invasive surgery. In: The 11th Asian Conference on Computer Aided Surgery (ACCAS 2015).
 Keyu Wu†, Liao Wu†, Hongliang Ren. An image based targeting method to guide a curvilinear concentric tube robot. In: Proceedings of 2014 IEEE International Conference on Robotics and Biomimetics (ROBIO 2014). Bali, Indonesia, 2014: 386-391 († equally contributed author).