Disclosed is a system proposed to enhance the effectiveness of computer aided surgery with a robot assisted needle insertion device in transcutaneous procedures.
Current practice for transcutaneous radiofrequency (RF) ablation involves a series of imaging and manual insertion based on the judgment of radiologists or surgeons. This method is tedious and often subject to uncertainties especially in the case of a large tumor where multiple needle insertions are required to destroy the entire tumor. Despite the development of sophisticated imaging modalities and surgical planning software, the bottleneck continues to be the uncertainty associated with intraoperative execution especially without real time image guidance.
While experienced surgeons may perform ablation therapy using real time ultrasound image guidance, this method has its disadvantages including the inadequacy in depth perception and the creation of a transient hyperechoic zone due to the microbubbles in ablated tissue.
The present invention addresses the foregoing problems in the art. In particular, a system and method of the invention provide robotic assistance and navigational guidance for needle placement in an overlapping ablation technique during tumor treatment. Example tumor areas effectively treated by the present invention may be one tumor of >3 cm diameter (for example), or multiple tumors near each other (each about 2-3 cm diameter for example) totaling 4 cm or more diameter target area, or other tumorous areas (formed of one or many localized tumors) of an effective size or volume requiring multiple ablations. In the prior and state of the art, multiple ablations of such relatively large tumor areas are difficult to perform accurately throughout and have no effective monitoring method. Hence embodiments of this invention present a solution to overcome these difficulties.
The present invention procedure of preoperative imaging and planning followed by intraoperative robotic execution of the ablation treatment plan is more systematic and consistent compared to the existing judgment based approach. A specialized robotic mechanism and control system are designed to execute preoperatively planned needle trajectories. Its navigation system combines mechanical linkage sensory units with an optical registration system. There is no demanding requirement for bulky hardware installation or expensive computational software modules.
The invention method and system can readily operate in any conventional operating theater. Apart from task requirements of the system, the apparatus also contains functional features that address safety and compatibility requirements in a surgical environment. In addition, the elegant design facilitates potential expansions. The application of orientation-transport and micro-macro manipulator design concepts makes the mechanism adaptive to the execution of complicated preoperative plans required to perform the overlapping ablation technique.
Two ex-vivo experiments and an in-vivo study are conducted with the developed prototype TRAINS, herein referenced as the preferred embodiment.
Embodiments (methods and systems of computer-aided surgery having robot assisted needle insertion) comprise: preoperatively imaging a target tumor area and planning target needle positions, resulting in a preoperative treatment plan;
The preoperative treatment plan has target needle positions in image coordinates. The step of translating thus (i) transforms target needle positions to real world coordinates and (ii) digitally computes a joint trajectory plan by converting a design specific kinematic model (for treating the target tumor area) to robotic paths.
The step of robotically executing is by a robotic manipulator and the 3D coordinate tracking system. This step includes confirming validity of placement of a first needle insertion (final position) and once confirmed, using the first needle placement (final position) as the reference for subsequent needle insertions and ablations of the joint trajectory plan.
The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.
a-2b are flow diagrams of data, control and operation of the embodiment of
A description of example embodiments of the invention follows. The teachings of all patents, published applications and references cited herein are incorporated by reference in their entirety.
The present invention introduces a transcutaneous robot assisted insertion navigation system that serves to bridge the gap in preoperative planning and intraoperative procedure by translating the preoperative plan into intraoperative execution consistently.
The preferred embodiment, the Transcutaneous Robot-assisted Ablation-device Insertion Navigation System (TRAINS) 100 is described now with reference to the Figures. Specific industrial applications include (but are not limited to): transcutaneous procedure for ablation therapy and needle placement in interventional procedures (including ablation therapy, biopsies, and laparoscopic procedures). Other applications are in the purview of those skilled in the art given this disclosure.
TRAINS is a system 100 for performing a transcutaneous procedure for ablation treatment in relatively large tumor areas (for non-limiting example, on the order of 2-3 cm diameter, formed of one or multiple close to each other tumors) through a preplanned robotic execution based on image diagnosis and a preoperative surgical plan. The invention system 100 comprises a robotic manipulator system 13 and a 3D coordinate tracking system 15 as illustrated in
A systematic approach to be executed with the developed prototypical system 100 is illustrated in
Next, the planned needle trajectories and ablation target positions computed in image coordinates 25 are mapped to real-world coordinates 27 through registration 26. Known registration techniques are used. The resulting target (real-world coordinates) data is used at computerized path planning step or module 33 to compute a joint trajectory 35 based on the design specific kinematic model (detailed later). Eventually the robotic manipulator 13 executes the preplanned path for needle placement 37 and delivers ablation therapy.
More specifically continuing from
An alternative embodiment is that after the final position of first needle placement 37 in the organ is confirmed (validated) via existing/known imaging modality such as ultrasound 39, a marker is placed at the target position prior to or after the ablation of the first needle placement 37. The marker may be an ultrasound contrast medium that can be injected into the tissue or other material that can be tracked external to the body. Robotic system 13 proceeds with the second and subsequent needle insertions and ablations of the registered plan 33. The marker may serve as the reference for subsequent insertions and calibration if needed as well as modification of surgical plan.
The robotic system 13 includes a novel manipulator mechanism together with its motion control software for execution of needle manipulation and insertion trajectories.
In a preferred embodiment, the specialized robotic arm (main manipulator unit) 41 is an 8 degree of freedom (DOF) serial manipulator comprising three passive links and five motorized axles. It applies the concept of a micro-macro manipulator for rapid deployment and fine placement of the needle.
In addition to the geometric optimization, this architecture also facilitates a more precise positioning during reinsertion of needles for multiple overlapping ablations. The translational approach in regional structure facilitates the implementation of a high-precision translational stage for joints (links) 4 and 5.
The complete design of the submanipulator assembly 43 in one embodiment is featured in
The entire robotic manipulator 13 can be mounted on to a wheeled mobile base 49 as showed in
The articulating nature of the manipulator 13 structure is advantageous for navigational trackers implementation. Wireless orientation sensors or encoders can be used for tracking the serial manipulator. Task coordinates can be obtained easily from joint coordinates 35 and vice versa by applying the appropriate Jacobian transformation. The closed form kinematic and dynamic model can be established. This is made possible by the design which partitions the multi-objective task of coarse needle transport, fine needle positioning and incision orientation. Hence, there is minimal need for demanding real time data acquisition and numerical computation of inverse kinematics. The invention system 100 uses an optical coordinate tracker 15 (
Embodiments of the present invention, such as preferred embodiment TRAINS 100, are resource efficient as each is specifically designed for transcutaneous ablation therapy. An embodiment 100 can be installed readily in any conventional operating theater or imaging center for outpatient surgery. Commercially available robotic systems capable of MIS do not serve as an efficient solution to the issue of RF ablation for relatively large tumor area treatment. As a result of the functional varieties of existing commercial surgical robotic systems, a larger operation envelope and more manpower are required to set up and operate them. It is therefore unpractical to utilize existing robotic surgical systems for transcutaneous procedures.
While there are many registration methods, tracking apparatus and surgical navigation systems, most of these operations are passive and involve manual control. They provide a form of spatial guidance but do not guarantee effective and consistent translation of preoperative plans to intraoperative executions. Applicant's introduction of robotic assistance in TRAINS 100 addresses this issue. Robotic execution of transcutaneous insertion ensures that multiple needle placement is consistent with the preplanned target.
The use of mechanical linkage sensory units and a vision based registration system 15 (discussed above) in tandem for surgical navigation is advantageous in terms of consistency, robustness and cost efficiency. This approach avoids the need to install expensive modalities like ultrasound localizers or high precision 3D vision systems which may not be available in a conventional operating theater.
The design of a mobile base 49 (
Accuracy of needle insertion is usually compromised by uncertainties like tissue deformation, needle deflection, motion of subject due to respiration or heartbeats, and registration misalignment. Respiration gait compensation can be integrated readily to the planning model at 33 (
Apart from transcutaneous needle insertion, the robotic system 100 can also perform ablation treatment in laparoscopic procedures. There may be instances where a transcutaneous procedure causes potential complications due to the location of the tumor or the limited task space capacity of the manipulator 13. The surgeon may decide to do a laparoscopic procedure if the needle 47 placement options risk inevitable burning of neighboring organs or the abdominal wall. In such situations the ability to execute software controlled RCM facilitates multiple needle insertions to treat relatively large tumor areas. The needle 47 can be pivoted remotely at an isocentric point constrained by the incision port.
A computation scheme to derive the inverse kinematics is presented. This computation method is designed for the proposed task-specific needle insertion for laparoscopic mode of operation. The computation method assigns the global frame of reference at the constrained entry point. For a given set of target insertion points, a corresponding set of end-effector 45 positions can be obtained. The end effector position refers to the position of Frame 7 (conventional frame assignments according to mobility of the needle 47) with respect to the global frame at the port. Hence joint coordinates (q4, qs, q6, q7, q8) can be computed such that the needle 47 is constrained within the entry port. The computational scheme is presented as follows:
Step 1: Compute end-effector position
For a given position of target PT(xT, yT, zT), find end-effector 45 position PE (xE, yE, zE).
Since our application uses a rigid needle 47, the corresponding end-effector 45 positions can be obtained from the target points with the following transformation as shown in equation (1).
P
E
=−I
k
P
T (1)
is the scaling matrix and
zE is the Z-axis coordinates of the end effector 45 and is a constant determined during the deployment of the submanipulator 43 discussed previously. The negative scaling matrix effectively maps the target position to the opposite octant of the 3D Cartesian space. This mapping relationship applies to the transformation of the distal end to the proximal end of any general rigid laparoscopic tools attached to the end effector 45.
Step 2: Obtain translational joint coordinate q4 and q5
By geometric inspection of the manipulator 13 design, the following relationship of the joint and task coordinates can be observed.
Step 3: Obtain joint coordinate q6, q7 and q8
As discussed previously, the remote center of motion can be analyzed as a multibody system with four degrees of freedom. For analyzing needle application, the orientation along the axial direction of the needle 47 shaft is not relevant. Hence the motion of the end effector 45 with respect to the global frame is analyzed as three degrees of freedom motion including rotation along X and Y axes, and translation along the axial direction of the needle 47 shaft. Mathematically, this can be represented by a homogenous transformation matrix shown in equation (3).
where Rk(θ) is a rotation of θ about k-axis and Pz(r) is a translation of r along Z-axis.
By comparing the position coordinates in the transformation matrix, the following expressions can be obtained.
This coordinate system is essentially a spherical coordinate system and can be related to our generalized joint coordinate system of 35 (
A computation scheme to obtain the relative transformation matrix from the incision point to the target point can be computed as illustrated below.
Step 1: Obtain transformation matrix of target point with respect to fiducial marker frame, MTT
M
T
T
=[K]
M′
T
T′ (8)
M and M′ denote frame assigned to the fiducial marker in world coordinates and image coordinates respectively. T and T′ denote frame assigned to target point in world and image coordinates.
Step 2: Obtain transformation matrix of incision port with respect to fiducial marker frame, PTM
The principle is to acquire a geometrical relationship of the incision port and the fiducial marker.
P
T
M=PTGGTM (9)
where P denotes frame assigned to incision port,
M denotes frame assigned to fiducial marker, and
G denotes a chosen global frame.
Step 3: Obtain transformation matrix of target point with respect to incision port, PTT
P
T
T=PTMMTT (10)
The coordinates are obtained from the 3D tracking system reference to a global frame.
While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
Other embodiments are further provided in “A Robotic System for Overlapping Radiofrequency Ablation in Large Tumor Treatment” by L. Yang, et al. in IEEE/ASME Transactions on Mechatronics, Vol. 15, No. 6, December 2010 (pgs. 887-897) a copy of which appears as Appendix I of the priority U.S. Provisional application herein incorporated in its entirety. Other details for embodiments are provided in Appendix II of the priority U.S. Provisional application herein incorporated in its entirety.
This application claims the benefit of U.S. Provisional Application No. 61/448,829 filed on Mar. 3, 2011. The entire teachings of the above application are incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
61448829 | Mar 2011 | US |