Patent Application
20110071380
This invention relates to tools for use in surgery and in particular manual tools that may be used for Minimally Invasive Surgery (MIS) such as prostate-related interventions: focal ablation, brachytherapy, and biopsy
The localized treatment of tumors and other medical conditions can be performed by: (i) focal ablation, coagulation of diseased tissue; and (ii) brachytherapy, the implantation of radioactive materials. Focal ablation is used to heat the tissue locally until it coagulates thus destroying the tumor cells. Implantation of radioactive implants directly into tumors results also in the destruction of the tumor cells. These types of surgeries are used for prostate therapy. An additional intervention is biopsy, a method of diagnosis of cancer.
One particular challenge with these types of surgeries is for the surgeon, during surgery, to know the location of the end of the interventional (surgical) needle with respect to the tumor, that is, the location of the element that comes into contact with the tumor, and provides the anatomical changes thereof.
Accordingly it would be advantageous to provide a method of locating the tip of the surgical instrument (needle) in real time and displaying that location on images of the organ or gland being surgically affected. Such medical images are obtained by ultrasound, or other type of imaging process such as MR (magnetic resonance).
The present invention relates to a medical device for use in association with a medical image of the gland or organ having a known reference point, the medical device comprising: a structural frame being positioned at a predetermined (and measurable) location relative to the medical image reference point; a horizontal joint operably connected to a horizontal position sensor and operably connected to the frame; a vertical joint operably connected to a vertical position sensor and operably connected to the frame; a pan joint operably connected to a pan position sensor and operably connected to the frame; a tilt joint operably connected a tilt position sensor and operably connected to the frame; a medical instrument assembly operably connected to a medical instrument position sensor and operably connected to the horizontal joint, the vertical joint, the pan joint and the tilt joint; a control system operably connected to the horizontal position sensor, the vertical position sensor, the pan position sensor, the tilt position sensor, the tilt position sensor and the medical instrument position sensor whereby the control system determines the position of a predetermined location on the medical instrument assembly relative to the structural frame.
The medical device may further include a mover being positioned at a predetermined location relative to the medical image reference point, wherein the frame is movably attached to the mover and may further include a means for determining the position of the frame relative to the mover such that the position of the frame is positioned at a predetermined location relative to the medical image reference point.
The horizontal joint and horizontal position sensor of the medical device may include a multi-turn potentiometer operably connected to an anti-backless spur gear and a rack, a linear guide unit operably connected to the rack, a locking mechanism operably connected to the rack and a means for moving the rack operably connected to the rack.
The vertical joint and horizontal position sensor of the medical device may include a multi-turn potentiometer operably connected to an anti-backless spur gear and a rack, a locking mechanism operably connected to the rack and a means for moving the rack operably connected to the rack.
The medical device as claimed in any one of claims 1 to 4 wherein the pan joint and pan position sensor includes a rotary potentiometer a pan joint support operably connected to the potentiometer and a locking mechanism operably connected to the potentiometer.
The tilt joint and tilt position sensor may include a rotary potentiometer a shaft operably connected to the potentiometer, a tilt joint support operably connected to the potentiometer and a locking mechanism.
The medical instrument assembly may be a needle assembly.
The needle assembly and medical instrument assembly position sensor may include a linear potentiometer, a needle tool operably connected to the linear potentiometer, a guiding shaft for receiving the needle tool, a lock operably connected to the guiding shaft, a slide block operably connected to the guiding shaft and a connector.
The medical image may be an ultrasound image or an MR image and it may be obtained in real time. Alternatively the medical image may be a blended real time ultrasound image and a pre-operative MR image.
In another aspect of the invention there is provided a method of positioning a medical instrument assembly comprising the steps of:
obtaining a magnetic resonance image of the organ or gland;
obtaining an ultrasound image of the organ or gland;
merging the magnetic resonance image with the ultrasound image to obtain a merged image;
determining a position of a predetermined point on the medical instrument assembly connected to a manual medical tool system; and
locating the position of the predetermined point on the merged image.
The position of the predetermined point of the medical instrument may be determined continuously in real time and a location of the point may move on the merged image as the medical instrument assembly moves.
The ultrasound image may be obtained continuously in real time.
The method may further include the step of determining a best path to reach a predetermined target in order to move the medical instrument and show the best path on the merged image.
In a further aspect of the invention a method of positioning a medical instrument assembly including a medical instrument comprises the steps of:
obtaining a magnetic resonance image;
determining a position of a predetermined point on the medical instrument assembly connected to a manual medical tool system; and
locating the position of the predetermined point on the magnetic resonance image.
The position of the predetermined point of the medical instrument may be determined continuously in real time and a location of the point may move on the magnetic resonance image as the medical instrument assembly moves.
The magnetic resonance image may be updated as the medical instrument is being moved.
The method may further include the step of determining a best path based to move the medical instrument and showing the best path on the magnetic resonance image.
The method may be used in association with minimally invasive surgery and the minimally invasive surgery may be chosen from the group consisting of focal ablation, brachytherapy and biopsy.
Further features of the invention will be described or will become apparent in the course of the following detailed description.
The invention will now be described by way of example only, with reference to the accompanying drawings, in which:
Referring to
The MIFAT system architecture is shown in
The treatment planning and monitoring software system is comprised of the a plurality of modules namely: 1) MRI and ultrasound image-fusion; 2) real-time ultrasound image capture and the contour overlay display; 3) a treatment planning (the best path optimization for the needle insertion); 4) an image-registered intervention; 5) desired needle insertion overlay on real time ultrasonic image; 6) user graphical interface (GUI).
For intervention, the patient is placed on the standard Operation Room (OR) table. The combined MIFAT device and TRUS probe are secured to a mover of precision stepper that is attached on a precision stabilizer mounted on the operating room table. The precision stepper and precision stabilizer may be obtained from Radiation Therapy Products (RTP).
Referring to
The MIFAT device 32 has two separate linear joints 42 to implement horizontal and vertical movements by manually, respectively.
The MIFAT device 32 also has two rotational joints 44: Pan (rotation in horizontal plane) and Tilt (rotation in vertical plane), shown in
The medical instrument assembly 36 is shown in
An alternative embodiment of the manual instrumented focal ablation tool constructed in accordance with the present invention is shown in
As seen in
In order to track the ultra-sound probe insertion depth during the procedure, a linear sensor 98 and a linear scale 100 are mounted on stepper 34 as shown on
Because the MIFAT is mounted mechanically on the stepper 34 (see
The manual medical tool is spatially registered to the ultrasound images. The real-time ultrasound images are transferred onto a computer that is also situated in the operating room.
The Software of MIFAT implements the following functions:
Potentiometers 102 are used to measure each position of needle on x, y, pan, tilt and also the penetration of the needle. The diagram is shown in
To display the real time ultrasound video from the ultrasound machine, MIFAT software captures the video out from the machine using a pinnacle 510-USB video capturer. To implement the video capturing, DirectShow™ technology is used. A class named CDSControl™ is built. There are more than 30 functions in this class to implement the capturing, filtering, overlaying and displaying for the video.
For the contour display, the VTK and DirectShow is used together. The Visualization Toolkit (VTK)™ is an open-source, freely available software system for 3D computer graphics, image processing, and visualization used by thousands of researchers and developers around the world. VTK may be used to produce the contour of the prostate and tumour. Preferably, first vtkSTLReader™ is used to read the 3D model of the tumour and prostate from the STL file (Note: “stl” is derived from the word “Stereolithography.” a stl file is a format used by Stereolithography software to generate information needed to produce 3D models on Stereolithography machines). Secondly a vtkPlane™ is used to define the current image plane based on the measure. Then a vtkcutter™ cut the 3D model to et a set of points which define the contour of prostate and tumour. Finally the two contours are overlaid on the realtime video using DirectShow.
Best path means a line through which a needle should go through and get a best treatment result. This requires the user to input the PTV (Planning Target Volume) as a binary mask, as well as an initial angle to optimize for, and constraints on the angles. The algorithm will determine the distance from a line at a given angle (with the centroid of the PTV being a point on that line), to each of the points in the PTV. The least squares sum of this distance is then minimized. This is implemented in the function get Initial Insertion Angle.
The best path may be determined in light of specific internal (anatomical) structures that the surgeon wishes to avoid. As well or in addition the best path may be determined in light of the volume of the tumor and the most effective path of a laser to the tumor.
Preferably the image area is on top left of the screen. The image in this area is captured from the real time video output of the TRUS unit, and the virtual contours of prostate and cancer are overlaid on the image.
A marker for “aiming” to the target is overlaid on the image. It can help the physician to aim the needle to the target before needle penetration based on the feedback from sensors. The marker indicates the predicted position of the needle tip when it reaches the transverse plane through the target. In order to remind the physician of the relative position of the tip of the needle, one of three statuses is shown on the image:
Preferably the video control area 110 is on the right of the screen. A sample video control area 110 is shown in
Preferably, the sensor information area 122 can control and show the information from the sensors, as shown in
Preferably, as shown in
Preferably, as shown in
Emulating experiments were designed with a prostate training phantom to demonstrate the MIFAT system. Three major issues for the experiments are described as below.
A commercial prostate training phantom 150 (CIRS Model 053A, shown in
For emulating experiments, the prostate phantom 150, the stepper and the tool device were rigidly attached to the base support. Because the tool device was mounted mechanically on the TRUS stepper, and the stepper was electronically encoded, the probe insertion depth with respect to stepper base and the tool frame was always identified on computer. Thus, the needle could be calibrated directly to the TRUS image.
Needle insertion and tracking: The goal was to demonstrate the placement of needle into the phantoms and the integration with the rest of the intra-operative system, especially with real-time ultrasound tracking.
The following sequences were executed in every needle insertion experiment:
The purpose of calibration was to determine the parameters which defined the transformation of a point in one coordinate system (i.e. an image) to another coordinate system. For MIFAT system, the real-time (or intra-operative) TRUS image had to be matched to the preoperative MR image so the needle tip could be accurately located according to the best path plan. And the needle tip had to be transformed to the fixed base frame.
The calibration procedure had the following components: manually positioning the TRUS probe so the real-time (or intra-operative) image shown on the computer-based User Interface was similar to the corresponding 2D contours—overlays, which were sliced on the prostate and lesions 3D model that were created with the pre-operative MR (or TRUS, just for the phantom experiments) images; registering the TRUS images to the needle guide via adjusting the mounting position of the phantom and the tool device.
The computer displayed a live 2D—prostate image on top left of its screen. The image was captured from the real-time video output of the TRUS machine, and the MRI-based virtual contours of the prostate were superimposed in green and the contours of the lesions were overlaid on the image.
Fused MRI/TRUS guidance needle intervention tracking tests were performed several times.
After manually moving the horizontal (X), vertical (Y), Pan and Tilt joints of the tool to the corresponding Entry coordinate created by the best path planning software, (While moving each joint, its displacement was being fed back to computer and shown in the corresponding test box of computer-based User Interface; also a green square “aiming” marker was shown on the image area, as shown in
Several experiments on a phantom have shown the capacity of MIFAT to reach its target with a few millimetres accuracy.
The experiments for emulating TRUS-guided interventions on a phantom have demonstrated the feasibility of the MIFAT concept, with fusing preoperative MR images to intra-operative TRUS image and resulting needle intervention accuracies estimated within the acceptable range of a few millimetres. It will likely improve the target accuracy in the future work.
For clinical practices (especially, at the stage of early prostate cancer), the 3D model of prostate and tumor should be created with the pre-operative MR images.
It will be appreciated by those skilled in the art that MIFAT could be used for other minimally invasive surgery such as brachy, biopsy and ablation. As well, the device could be used conjunction with other medical instrument assemblies in other surgical procedures. In addition, it will be appreciated by those skilled in the art that the MIFAT could also be used in association with a magnetic resonance imager (MRI). If MIFAT is used with an MRI the medical instrument assembly position and best path will be shown on the MR image as the medical instrument is being positioned in the patient.
Generally speaking, the systems described herein are directed to the MIFAT device. As required, embodiments of the present invention are disclosed herein. However, the disclosed embodiments are merely exemplary, and it should be understood that the invention may be embodied in many various and alternative forms. The Figures are not to scale and some features may be exaggerated or minimized to show details of particular elements while related elements may have been eliminated to prevent obscuring novel aspects. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention. For purposes of teaching and not limitation, the illustrated embodiments are directed to a MIFAT device and the MIFAT system.
As used herein, the terms “comprises” and “comprising” are to be construed as being inclusive and opened rather than exclusive. Specifically, when used in this specification including the claims, the terms “comprises” and “comprising” and variations thereof mean that the specified features, steps or components are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.
This patent application relates to U.S. Provisional Patent Application Ser. No. 61/272,296 filed on Sep. 9, 2009 entitled MANUAL INSTRUMENTED MEDICAL TOOL SYSTEM which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61272296 | Sep 2009 | US |
