A Novel Robotic Bronchoscope System for Navigation and Biopsy of Pulmonary Lesions

Abstract

Transbronchial biopsy sampling, as a minimally invasive method with relatively low risk, has been proved to be a promising treatment in the field of respiratory surgery. Although several robotic bronchoscopes have been developed, it remains a great challenge to balance size and flexibility, while integrating multisensors to realize navigation during complex airway networks. This paper proposes a novel robotic bronchoscope system composed by end effector with relatively small size, relevant actuation unit, and navigation system with path planning and surgical guidance capability. The main part of the end effector is machined by bidirectional groove on a nickel-titanium tube, which can realize bending, rotation, and translation 3 degrees of freedom. A prototype of the proposed robotic bronchoscope system is designed and fabricated, and its performance is tested through several experiments to verify the stiffness, flexibility, and navigation performance. The results show that the proposed system is with good environment adaptiveness, and it can become a promising biopsy method through natural cavity of the human body.

Fig. 1.

Mechanism design of the robotic bronchoscope system. (A) The overall system contains 2 parts: end effector and actuation unit. Coil springs are added to realize variable stiffness capability. OD, outer diameter; ID, inner diameter. (B) End effector is composed by Ni–Ti tube, tip section, and several spacer discs. PTFE outer sleeve is for the variable length of bending section capability.

Fig. 2.

Kinematics and cavity passage capability analysis. (A) Kinematics model and coordinate systems. (B) Regular reachable workspace. (C) Augmented workspace by variable length of bending section capability. (D) Examples of robot posture in bronchus. Case i and ii, restricted by bifurcation and channel wall without certain capability; case iii, successful entry into target bronchus with certain capability.

Fig. 3.

Navigation system workflow. (A) The overall framework and the purpose of it are to localize the tip of robotic bronchoscope in the complex airway networks. (B) Surgical path planning procedures. Step 1 is the entry point, step 2 is the target point, and step 3 is the generated path. CT, computed tomography.

Fig. 4.

Stiffness test. (A) Experimental setup. (B and C) Setup for low and high stiffness states. The tensions of the coil springs are different. (D) Results of stiffness test.

Fig. 5.

Flexibility test. (A) Experimental setup. (B to D) Examples of robot posture in phantom. Red points illustrate that the robot is restricted by channel wall, while green point illustrates that the robot enters target branch successfully with a relatively short length of bending section.

Fig. 6.

Navigation-assisted intervention experiment. (A) Experimental setup. (B) One scene of end effector in the phantom during experiments. (C) Corresponding navigation system display. FG, field generator; SCU, system control unit; SIU, sensor interface unit; UI, user interface.