An Endoluminal Robotic Platform for Minimally Invasive Surgery

Transcription

1 The Fourth IEEE RAS/EMBS International Conference on Biomedical Robotics and Biomechatronics Roma, Italy. June 24-27, 2012 An Endoluminal Robotic Platform for Minimally Invasive Surgery S. Tognarelli, Member IEEE, M. Salerno, G. Tortora, Student Member IEEE, C. Quaglia, P. Dario, Fellow, IEEE, A. Menciassi, Member, IEEE Abstract²During past years, Natural Orifice Translumenal Endoscopic Surgery (NOTES) has been introduced in the medical scenario, leading to the miniaturization of robotic systems and harboring the concept of inserting functional units into the human body for performing surgery. An innovative endoluminal robotic platform for Minimally Invasive Surgery (MIS), and more specifically for NOTES, has been developed and tested. The platform is composed of a miniaturized camera robot coupled with an anchoring frame conceived to assure adequate robotic stability inside the abdominal cavity during surgical tasks. The anchoring frame consists of a Shape Memory Alloy (SMA) actuated magnetic frame attached to the abdominal wall by means of permanent magnets. A dedicated docking mechanism has been integrated in order to assure positioning and anchoring of robotic modules. All platform elements have been specifically designed for NOTES applications: the magnetic frame and the robotic camera module have a diameter of 14 mm and 12 mm respectively. In this work, the endoluminal platform has been illustrated and its potentialities demonstrated in in-vitro conditions on a human phantom. T I. INTRODUCTION echnological advances allowed significant improvements in surgery aiming to reduce operative invasiveness. Specialized tools and innovative instruments allowed to overcome drawbacks in visualization and manipulation tasks, making laparoscopy the state of the art for most surgical procedures. Recently, Natural Orifice Translumenal Endoscopic Surgery (NOTES) has been introduced in the surgical setting with the purpose of making surgery even less invasive: by using a natural orifice, such as the upper gastrointestinal tract, the peritoneal cavity can be reached eliminating external incisions [1]. Based on this, NOTES approach has nowadays the potential to again revolutionize general surgery likewise laparoscopy did in the past [2]. Even if there is still some debate on the appropriateness of NOTES, the transition from laparoscopy to NOTES offers most of the advantages of laparoscopy, including pain reduction, short patient recovery time, and better aesthetics results by using natural orifices for reaching the operative site. NOTES technique is very appealing from WKHSDWLHQW VSHUVSHFWLYHbut it introduces additional surgical and technical challenges for the physicians. The insertion port is limited to the size of the selected natural orifice (e.g. Manuscript received on January 31, This work was supported by the European Commission in the framework of the ARAKNES FP7 European Project All authors are with The BioRobotics Institute, Scuola Superiore 6DQW $QQD3LVD,WDO\H-mail: n.surname@sssup.it). ST is the corresponding author ( s.tognarelli@sssup.it). mouth, anus, vagina), losing the possibility to insert multiple instruments through the same access simultaneously. Moreover, NOTES instruments must be adequately flexible to go through the natural orifice and to follow both the anatomical curvature and the physiological lumen. Since current endoscopic tools are inadequate for NOTES procedures, new technologies are needed to face with these challenges and improve the surgeon abilities in a NOTES approach. Robotics has already significantly influenced laparoscopy and could allow notable advancements in NOTES as well. The da Vinci Surgical System (Intuitive Surgical, CA, USA) represents successful commercially available telerobotic system installed worldwide ( However, it still requires traditional laparoscopic accesses for arms insertion, and consequently, it requires the same level of invasiveness. Much effort is currently being directed towards the development of next-generation robotic systems [3]-[5], but limited results have been obtained for NOTES because few robots are capable of navigating the complex anatomical geometry of a natural lumen. Other solutions have been proposed for Single Port Laparoscopy (SPL) [6],[7]. However, these systems are activated by an external driving system, and they will always be constrained by the entry point. In this framework, innovative miniature in-vivo robots are being introduced with the final aim to provide vision and assistive tasks to the surgeon preserving the overall flexibility. Significant examples of innovative robotic devices have been investigated worldwide for NOTES procedures [8]-[10] or for vision purposes in Minimally Invasive Surgery (MIS) [11], [12]. Moreover, by exploiting the intrinsic nature of the in-vivo robot, multiple devices can be deployed in the abdominal cavity through a single access point, by leaving back just thin wires for powering or image delivering [13]. In order to use in-vivo robots as a complete surgical platform for NOTES procedures, and not only as assistive tools for specific surgical tasks, a new design approach is needed. A stable frame for tissue manipulation and/or visualization tasks is required, that also allows for the necessary flexibility for system insertion through natural orifices. Based on the above considerations, an innovative endoluminal robotic platform has been developed for addressing all the requirements (such as dexterity and stability) for making NOTES procedures actually feasible thanks to different actuation solutions. By exploiting the magnetic attraction force between a couple of magnets, housed in the robotic system and outside of the patient respectively, an actuated frame equipped with a dedicated /12/$ IEEE 7

2 docking mechanism for the anchoring of miniaturized robots has been realized and tested. This paper briefly describes the design of the modular robotic units that compose the platform, the successful assembly of the system in a phantom model, and the in-vitro evaluation in order to assess the feasibility of the proposed approach. (a) (b) II. SYSTEM DESIGN In this section we present the development methodology of an innovative robotic platform for NOTES procedures, based on a modular approach allowing to implement a multifunctional miniaturized system inside the abdominal cavity. The concept of reconfigurable modular robotic system has been exploited to improve the platform kinematics in endoluminal interventions. Based on this objective, the proposed platform is composed of internal (intra-abdominal) and external (extracorporeal) components, which are magnetically coupled across the abdominal wall via magnetic attraction force (Fig. 1). The internal unit consists of an actuated triangular-shaped magnetic frame equipped with a dedicated docking mechanism for the anchoring of miniaturized modular robotic units (Fig. 2). The actuated magnetic frame allows to anchor in-vivo robots inside the abdominal cavity thus guaranteeing to reach the stable adhesion necessary for complete surgical interventions. Moreover, the triangular shape allows the anchoring of several robotic units at the same time, without any additional incisions. Finally, the insertion configurations of both the magnetic frame and the robotic units allows to reach the abdominal cavity following the anatomical curvature of the human esophagus, and thus avoiding any damage to the tissues. As described in [14], essential robotic units in any surgical procedure are image acquisition unit, retraction unit and manipulator unit. The need of different robots complicates the platform design since different units apparently require a different design, and consequently a different docking mechanism for anchoring to the frame. In this framework, the main purpose of this work is to present a general purpose design of the anchoring frame that can be used in a wide range of surgical tasks. As robotic module, a camera robot will be illustrated in this paper, but considerations related to docking systems and anchoring problems can be applied to any kind of miniaturized robotic modules, such as manipulators and/or retractors. The internal anchoring frame contains three couples of magnets placed at each frame side and, when inside the abdominal cavity, it is manipulated by using an external hand-held magnetic device positioned on the external surface of the abdomen. If surgical modules are stably attached to the anchoring magnetic frame, the surgical ZRUNVSDFHFDQEH³WUDQVODWHG LQGLIIHUHQWSRVLWLRQVRIWKH abdomen, thus optimizing the operating conditions for the operator. The external hand-held magnetic frame assures adequate robotic stability and proper range of motion, thus adding external Degrees of Freedom (DoFs) to the intraabdominal components. (c) Fig. 1. Magnetic frame (a) and mock-up of the robot (b) during insertion phase; assembled version of the endoluminal robotic platform: intraabdominal (c) and extracorporeal (d) view. Fig. 2. Internal unit of the endoluminal platform: miniature camera module anchored on the actuated triangular-shaped magnetic frame equipped with a dedicated docking mechanism. A. Robotic platform design The internal surgical platform is composed by three modules, there are illustrated below. 1) Anchoring frame. Solid and stable adhesion to the abdominal wall is required to guarantee accuracy and precision in surgical tasks [15]. Moreover, in NOTES, small actuators should be used for allowing to reach the abdominal cavity by using a natural orifice. According to this, a dedicated Shape Memory Alloy (SMA) actuated anchoring frame has been developed and magnetic attraction force between the internal frame and an external hand-held magnetic module has been exploited. The diameter for the anchoring frame should be no bigger than 14 mm in order to be safely inserted into the abdominal cavity without any damage for the patient tissues. Moreover, the length of rigid parts should be compatible with the esophagus anatomy, in order to safely follow the lumen curvature up to the stomach and pass through the gastric wall for reaching the abdominal cavity. Consequently, the design of an active frame with two different configurations (i.e. open and close), enabling flexibility for system delivery (i.e. insertion and extraction) and rigidity during surgical operations, has been carried out. The basic design consists of introducing an actuator at each joint of the triangular frame, that allow to pass from close to open configuration and viceversa. Being the size limitation the main difficulty in the endoscopic delivery of robotic devices, SMA actuators (d) 8

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5 configuration (from close to open) and for allowing system deployment; (c) deployment of the triangular shaped magnetic frame in the phantom abdomen by using a traditional flexible endoscope (STORZ, PKS, Head V2.4, Germany); (d) SMA spring cooling process for coming back to triangular shaped configuration; (e) frame stabilization and anchoring by means of the external handheld magnetic system; (f) deployment of the miniature robotic module into the gastric cavity, passing through the endoscopic overtube by pushing again with the flexible endoscope; (g) anchoring of the robotic module into the docking mechanism; (h) un-docking process once performed the surgical inspection; (i) re-opening procedure by supplying current to the SMA actuators of the frame and frame retraction through the phantom esophagus. The protocol has been repeated 3 times to decrease single procedure time, and to test procedure reliability and repeatability. The steps of the above protocol are illustrated in the companion video. IV. RESULTS The feasibility of the proposed endoluminal platform for NOTES procedures has been validated by means of in-vitro tests on a gastric medical training phantom. The medical procedure for system deployment, magnetic anchoring, robot docking and un-docking has been successful (see attached video for details). By introducing the activated SMA system through the endoscopic overtube, the phantom abdomen has been easily reached; power supply has been switched off for reaching the triangular-shaped close configuration and magnetic coupling with the external magnetic handle has been assured. In order to record the entire procedure from outside, a see-through plexiglass surface has been used for simulating the patient abdominal wall. The high rigidity of this simulated abdominal wall makes difficult and time consuming the anchoring procedure. In in-vivo conditions, the abdominal wall is highly deformable, so that the operator can push down the external frame and consequently he/she can exploit the magnetic attraction force between the external and the internal magnets for frame lifting. Fig. 7. Tobii X50 eyetracker data for robot control, raw (right) and filtered (left) fixations. Fig. 8. Raw (red) and filtered (blue) fixations (left) and corresponding robot position within the motion range (right). A continuous current has been used to change the SMA frame configuration (close-open) in about 5-10 s; the average time for completing the introduction, positioning and anchoring procedure of the triangular module has been 10 minutes with a very steep learning curve (after a few tests this time becomes as short as 8 minutes). After that, the modular camera robot has been inserted into the phantom abdominal cavity and attached to the docking areas by using a running wire (see attached video). The action of the running wire together with the magnetic force allowed the proper alignment of the robot as well as a reliable docking. Further position adjustment of the robot is obtained by activating the internal motors, thus making easier the robot insertion in the docking system. For the following undocking phase of the camera robot, the mechanism based on the R module has been exploited: with the rotational movement of the base module, adequate torque has been produced for decoupling/misaligning the magnets housed in the triangular frame and in the robotic camera respectively. Finally, platform disassembly and components retraction have been executed to close the in-vitro test session. In average, the complete procedure of frame deployment, frame anchoring, robot docking and un-docking and system final retraction required about 30 minutes. This value results compatible with results described in literature for complete NOTES procedures [18]. Details about the experimental tests have been reported in the attached video, where all the procedure steps have been recorded. Regarding the HMI, preliminary results have been obtained by testing the eye-tracking system and the robotic camera separately from the overall platform. The results show how raw fixations are correctly filtered to the exact quadrant on the screen they belong to, and how both camera robotic joints follow the intended path without deviations (Fig. 7 and Fig. 8). As the motion sequence is Down, Up, Left, Right, the P joint is fixed to its maximum ³8S position before the horizontal motion is applied to the R joint, thus H[SODLQLQJWKHµ7 VKDSHRIWKHJUDSK (Fig. 8 on the right). Although, the eye-tracking system has been proved to work for controlling the camera robot, its key advantages benefits respect to a hand-controlled joystick will be assessed in future. V. CONCLUSIONS AND FUTURE WORK In this paper, an innovative endoluminal platform for MIS tasks and more specifically for NOTES procedures has been 11

6 proposed. The concept of modular robotic units is aimed to improve current robotic surgery by means of small, redundant and less bulky devices. Starting from this consideration, a modular system composed by an articulated robotic camera and a home-made anchoring platform has been described, developed and tested. The potentials of the proposed platform have been demonstrated in in-vitro conditions by using a commercial gastro-bulboscopy human phantom. Preliminary experiences have been gained and good results have been obtained in terms of procedure feasibility; however, future efforts will be devoted to improve the current version of the endoluminal platform with the aim to enhance the system capabilities and widening surgical applications. As regards the triangular anchoring frame and the external hand-held device, custom magnets could be used in more advanced prototypes with the double aim to: 1) improve the coupling strength by increasing the magnetic attraction force and 2) scale down the diameter of the SMA actuated magnetic frame. A miniaturized version of the platform could indeed be beneficial not only for NOTES procedures in smaller anatomies, but also for traditional minimally invasive procedures with trocar diameters of 12 mm. Concerning the modular robotic unit, encouraging results have been obtained with the 2 DoFs camera robot, demonstrating that the assembled platform is a valid solution for providing medical assistance in vision tasks during a NOTES procedure. Stable anchoring has been provided and simple docking and un-docking mechanisms have been validated. Moreover, the proposed docking mechanism, with slight modifications, can be adapted to different robotic modules (e.g. retractors or manipulators). However, being the rotational movement of the R module used both for R motion and for the module detachment, the proposed undocking mechanism could not be the most appropriate solution for advanced surgical robotic modules equipped with multi DoFs, such as a retraction module or a 6 DoFs manipulator robot. In order to avoid any unintentional module detachment during surgical tasks implying a roll movement, alternative solutions are required. The concept of a SMA actuated docking mechanism has been investigated and a preliminary prototype is currently under design. Finally, an in-vivo test session on animal model has been planned for the next months in order to validate the proposed platform in a real surgical scenario. [2] $)RUJLRQH³,QYLYRPLFURURERWVIRUQDWXUDORULILFHWUDQVOXPLQDO surgery. Current status and future phuvshfwlyhv Surg Oncol, vol. 18, pp , [3] ' &KRL DQG & 5LYLHUH ³)OH[XUH-based manipulator for active KDQGKHOGPLFURVXJLFDOLQVWUXPHQW LQ 2005 Proc. Annu. Conf. IEEE Engineering in Medicine and Biology Society (EMBS), Sep [4] J. A. Ding, et al.³'hvljq6lpxodwlrqdqg(ydoxdwlrqri.lqhpdwlf Alternatives for Insertable Robotic Effectors Platforms in Single Port $FFHVV6XUJHU\ LQ2010 Proc. ICRA Conf, pp [5] U. Hagn, et al.³'/50lur6xujhdyhuvdwlohv\vwhpiruuhvhdufklq engrvfrslf7hohvxujhu\ Int J CARS, vol. 5, pp.183±193, [6] G-P Haber,et al., Novel Robotic da Vinci Instruments for Laparoendoscopic Single-site Surgery, Rapid Communication, Urology,vol. 76, pp , [7] M. Piccigallo, U. Scarfogliero, C. Quaglia, G. Petroni, P. Valdastri, A. Menciassi, P. Dario, Design of a Novel Bimanual Robotic System for Single-Port Laparoscopy, IEEE Transaction on Mechatronics, vol 16, no. 6, pp , [8] D. J. Scott, et al. ³&RPSOHWHO\WUDQVYDJLQDOQRWHVFKROHF\VWHFWRmy XVLQJPDJQHWLFDOO\DQFKRUHGLQVWUXPHQWV Surg Endosc, vol. 21, no. 12, pp. : , [9] A. C. Lehman, et al.³1dwxudorulilfhfkrohf\vwhfwrp\xvlqjd PLQLDWXUHURERW Surg Endosc, vol. 23, pp. 260±266, [10] A. C. Lehman, et al.³dexterous miniature robot for advanced PLQLPDOO\LQYDVLYHVXUJHU\ Surg. Endosc., vol. 25, no. 1, pp , Jan [11] S. Park et al³7urfdu- less instrumentation for laparoscopy magnetic positioning of intra-degrplqdofdphuddqguhwudfwru Ann. Surg., vol. 245, pp , [12] 7+X3.$OOHQ1-+RJOHDQG'/)RZOHU³,QVHUWDEOHVXUJLFDO LPDJLQJGHYLFHZLWKSDQWLOW]RRPDQGOLJKWLQJ Int. J. Robot. Res. vol. 28, no. 10, pp , [13] K. Harada, et al.³$uhfrqiljxudeohprgxoduurerwlfhqgoluminal VXUJLFDOV\VWHPYLVLRQDQGSUHOLPLQDU\UHVXOWV Robotica, vol. First View, pp. 1-13, [14] G. Tortora, A. Dimitracopoulos, P. Valdastri, A. Menciassi and P. 'DULR ³'HVLJQ RI 0LQLDWXUH 0RGXODU LQ YLYR 5RERWV IRU'HGLFDWHG Tasks in Minimally InvDVLYH 6XUJHU\ LQ Proc. IEEE/ASME International Conference on Advanced Intelligent Mechatronics Conference, pp [15] G. W. Taylor, et al.³:hwdgkhvlrqirudplqldwxuhprelohlqwud- DEGRPLQDOGHYLFHEDVHGRQELRPLPHWLFSULQFLSOHV Proc. IMechE ± J. Mechanical Engineering Science, vol. 224, pp , [16] T. Waram, Actuator design using shape memory alloys, 2nd ed. (Metri), Hamilton, Ont [17] $1HVSROL6%HVVHJKLQL63LWWDFFLR(9LOODDQG69LVFXVR³7KH high potential of shape memory alloys in developing miniature mechanical devices: A review on shape memory alloy mini- DFWXDWRUV Sensor Actuat. A-Phys., vol. 158, pp. 149±160, [18] D. J. Scott, et al.³&rpsohwho\wudqvydjlqdo127(6fkrohf\vwhfwrp\ using magnetically anchored instrumeqwv Surg. Endosc., vol. 21, pp. 2308±2316, ACKNOWLEDGMENT The authors wish to thank A. Melani, N. Funaro and C. Filippeschi for prototypes manufacturing, M. Silvestri and M. Visentini Scarzanella for the invaluable support. REFERENCES [1] S. A. Giday, S. V. Kantsevoy, and A. N. Kalloo, "Principle and History of Natural Orifice Translumenal Endoscopic Surgery (NOTES)," Minimally Invasive Therapy and Allied Technologies, vol. 15, no.6, pp ,