DE102012002412A1 - Device for determination of position of puncture needle in workspace of ultrasound probe for human body, has processor unit introducing stitch projection and penetration depth of needle together with image for representation of projection - Google Patents

Abstract

The device has a lens projecting an object point in a workspace parallel to a midpoint beam on pixels of a charge coupled device camera (4), where light is received through the lens. Image information of the camera, incidence angle of a linear detection light beam and ultrasound image are supplied to a processor unit. The processor unit introduces a stitch projection in a position at an angle, an intersection point of the stitch projection in plane-sound plumbing and penetration depth of a puncture needle together with the ultrasound image for representation of the projection. An independent claim is also included for a kit comprising a determination device.

Description

Problem and state of the art

The vessels and nerves in the human body are mostly invisible from the outside. Your puncture requires good knowledge of the anatomy of the puncture target and the adjacent anatomical lead structures that help with orientation. Ultrasound scans provide the ability to visualize the target structures by creating a two-dimensional image of the target and the surrounding tissue. The coordination of the ultrasound image with the position and sting direction of the puncture needle is made difficult by several circumstances. The plane of the two-dimensional ultrasound image and the position of the puncture needle inserted into the body are usually so far apart that the target structure and needle can not be displayed together in the ultrasound image by tilting and moving the sound probe. This problem increases with the distance between the insertion position of the needle and the position of the sound probe. Furthermore, puncture needles - especially thin needles suitable for performing nerve blocks - are difficult to see in the ultrasound image ( MAECKEN et al. 2007 ).

The anatomical situation of an ultrasound - controlled puncture of a branch of the median nerve extending into the left hand is in 2 shown. The sound probe is placed on the palmar side of the forearm in the area of the wrist. The line through which the sound enters the tissue of the arm placed on the skin of the arm is referred to below as the X-axis, the direction in which the ultrasound propagates into the depth of the tissue, as the Z-axis, the sound designated. Accordingly, let the radial intersection of the Z-axis with the X-axis be defined as 0 point of the coordinate system of the Schalllotung, with the Y-axis of the Schalllotung located at right angles from the X and Z axis on the skin in front of the sound probe. The angle between X- and Z-axis is rectangular, whereas the angle between Z- and Y-axis depends on the angle of inclination, or on the tilting position of the X-axis rotatable sound probe (about 45-135 GRT) For example, this angle is also rectangular.). In the working space of the ultrasound-guided puncture, a puncture needle is placed on the skin of the forearm. The ray which continues as an extension of this attached puncture needle below the skin level is as a stitch projection, as a broken line in 2 shown. In the three-dimensional coordinate system, the puncture needle in the graph formed of the X- and Z-axes may be in the plane of the sounding as the projection line S (x, z) and in the graph formed of the Y- and Z-axes are represented as projection line S (y, z) ( 2 ). The other illustrations thus relate to a three-dimensional rectangular coordinate system. The stitch projection S (x, z) is located in the plane of the sound slot and therefore appears in the ultrasound image, as in the graph of the X and Z axis as a straight line. At which point of this straight line the pierced needle is projected depends on the steepness of the puncture and thus on the angle Ay. The point of intersection of the stitch projections in the plane of the sound sounding is indicated below by a marker ( 1 , T><T) is displayed on the line S (x, z) in the image of the sound sounding.

Chan et al. (2005) such as Najafi and Rohling (2011) describe the optical detection of the position of puncture needles by monocular and binocular camera systems, which are mounted on the sound probe and look at the located in front of the sound probe working space of the puncture needle. In experiments on models, the authors were able to reliably detect the position of injection needles in the space in front of the sound probe after appropriate calibration of each camera.

Our own attempts to image puncture needles with corresponding monocular and binocular camera systems of comparable quality, however, show that the presentation of suitable for the conduct of local anesthesia puncture needles - 20 to 24 gauge needles were used - under the prevailing conditions in operating rooms significantly more difficult.

Above all, it has been shown that, the illumination of the working space in front of the sound probe by the necessary movements of needle and sound probe under the light conditions present in operating rooms is constantly changing. In addition, when placed at a shallow angle to the skin shorter needles parts of the hand movements of the surgeon in the field of view of the camera systems take place. The lighting conditions in the working area in front of the sound probe can be improved by suitable lighting means, which are attached to the sound probe and illuminate the working space. Nonetheless, several problems remain in the practical implementation:
The vast majority of the procedures are not performed by injections in even skin surfaces but in curved anatomical structures. In the usual conduction blocks such as axillary plexus blockages, scalenus blockages, local anesthesia of the ganglion stellatum, anterior infraclavicular blockades, blockages of the femoral nerve, popliteal blocks as well as vascular punctures such as the puncture of the internal jugular vein, the subclavian vein and the femoral vein, take on sound probes mounted Cameras needle images in front of him changing backgrounds of changing illuminated and moving body surfaces and cavities.

In the ultrasound-sonographically navigated puncture, the sound probe is placed on or pressed into the body surface in different ways. Especially with local anesthesia and vascular punctures, the changes in the tissue in the sound image, which are triggered by different firm pressing the sound probe, an important criterion for the identification of the sonografierten body structure (distinction of veins, arteries, nerve cords and tendons). Also sound probes are rotated over the tissue and tilted to capture the spatial shape of the structures in the tissue. In each of these manipulations, both the backgrounds of the body surface detected by the cameras and the light reflected by the needle change.

The topological anatomical conditions in the working space in front of ultrasound probes considerably complicate the analysis by camera systems of recorded images. Almost at all positions of the ultrasound probe caused by the necessary inclinations of the puncture needle silhouettes of the needle on the body surface.

The knowledge of the penetration depth of the needle necessary for the correct puncture forces a corresponding marking of the needle when using navigation systems. Furthermore, in systems for the three-dimensional representation of the puncture needle layer it is recommended to use markings on the puncture needle which define at least one specific location of the puncture needle for camera systems. In the light conditions present in operating rooms, it is very difficult to visually mark puncture needles for camera systems. In order to avoid injury during the puncture, the diameter of the needle must not be increased by the markings. The needle surface should not be additionally roughened by markings for the same reason. However, markings which are easily identifiable with camera systems considerably exceed the space provided by common local anesthetic baths.

Furthermore, the germ-free envelope of the sound probe presents a further problem. Ultrasonic probes must be enveloped with sterile foils for sterile coverage in order to avoid the bacterial contamination of the puncture site. The irregular arrangement of such translucent envelopes disturbs the reproduction of the needle image considerably. The movements of the film sections in front of the camera caused by the operator disturb the optical quality of the camera image considerably.

Description of the invention

In a simple embodiment of the invention, the position of the puncture needle by means of at least two light beams hereinafter referred to as locating light beams (O) and determined at least one photodetector. The two locating light beams successively pass over a horizontal sector of equal height Z0 or Z1 in the area in front of the sound probe ( 3 ). When sweeping the puncture needle, the light is reflected by the needle and reflected back to a mounted on the front of the sound probe light detector. The angle between the x-axis and the pin which hits the pin ( 3 α1, β1, α2, β2) can be determined, for example, from the angular velocity of the rotating light beam and the time required for the light beam to pass from the Z-line (0 GRT) to reach the reflective puncture needle. For this purpose, in each case a photodiode can be mounted in the interior of the Meßvorichtung so that they can be detected by the locating light beam when driving over a defined position z. B. the Z-line is illuminated, wherein the light pulse is measured with a measuring amplifier and fed to a computer. When the light of two rotating locating light beams (L1, L2) from different positions of the X-axis hits a point of the puncturing needle and the light reflected from this point is incident on the photodetector located in front of the sonic probe (FIG. 3 D), this point P (x1, y1, z1) on the puncture needle and the light sources L1 and L2 can be considered as a triangle. The triangle is in 3 The upper side C is delimited by the vertices L1 and L2. The vertex P (x1, y1, z1) opposite the base C is achieved with a beam of L1 with the inside angle α1 and with a beam of L2 with the inside angle β1. The height (Y1) dropped from P (x1, y1, z1) to baseline C divides C into sections x1 and q. X1 corresponds to the intersection of the stitch projection at the level of the skin level (see 1 ).

Another point on the puncture needle P (x2, y2, z2) can be optically detected in the same way by another pair of rotatably held detection light beams L3 and L4, which run parallel to the light sources described above, two other sectors in front of the sound probe. With this additional, spatial information for P1 and P2, the position of the stitch projection S (x / z), x1, x2 and the angle Az as well as the passage of the stitch projection in the plane of the sound sounding ( 1 T><T) and displayed on the sound image. The 4 shows an exemplary embodiment of the invention without limiting it thereto. The locating light beams ( 4 , O) are detected by means of the light sources ( 4 left top, bottom left) and by mirror on the rotating mirror ( 4 DS) deflected. For synchronous rotation, the two rotating mirrors (DS) are connected to each other by a toothed belt or by a gear, which engage in each one connected to DS pinion. For better clarity, see 4 to the figure of a toothed belt driving motor, as well as the representation of the electrical lines to light sources and photodetectors have been omitted. In 4 bottom right is the provided with slit-shaped panels end plate of the device with a photodetector for measuring the reflected light from the puncture detection beam (O). In the in 4 In the illustrated example of the invention, the rotatably supported light sources (L1, L2, L3, L4) are provided with means for measuring the angles of the locating light beams (O) radiated into the area in front of the sound probe. The measurements angle of the location light beams can be done by incremental encoder, which are connected via corresponding USB connections directly to the computer, which is also connected to the camera and ultrasound device. The two locating light beams can be advantageously rotated in opposite directions by a gear, so that each locating light beam passes successively from one outside to the other inside the working space.

In further studies, the intensities of detection light rays reflected by various puncture needles (20-23 gauge diameter) have been investigated. In addition to the measurement of the returned light intensities with individual photodiodes, measurements of the light reflected by the puncture needles in the camera image of a CCD camera mounted on the ultrasound probe have also been recorded. For this purpose, a lens is in front of the CCD camera ( 5 . 6 ) consisting of at least one converging lens ( 5.1 ) and a mirror ( 5.2 ) has been pre-set so that each object point in the working space, parallel to the line of the center beam of the lens on a corresponding pixel of the camera comes for imaging. The axis-parallel representation of the working space on the image plane of the camera is effected by installing a lens with a sufficiently strong overall focal length. The necessary for handling small size of the navigation device can be advantageously achieved by a deflection mirror ( 1 . 5.2 . 3 . 5.2 . 4 . 5.2 ) without substantial losses in the quality of the lens. The beam path through the lens is in 7 represented, wherein the reflection of the beam path has not been reproduced upwards for clarity. The mirror is only hatched indicated ( 5.2 ), the beam path has been shown in one plane. In the lower section of the 7 is the angle of the irradiated location light beam α of the laser ( 6 ). On the right side is the right-angled triangle, which can be constructed from the angle α of the tracking light beam, from the reflection line (Y1) and from the distance X1 of the camera image. This triangle of which α and X1 are known, respectively, is the basis of the triangulations performed by the arithmetic unit. The 5 1 shows an application example of an arrangement with an axis-parallel projecting objective, consisting of a 7.5 d Fresnel lens (FIG. 5.1 ), a deflection mirror ( 5.2 ); a CCD camera ( 4 ) and an ultrasound device ( 2 ). The desired axis-parallel projection of all object points of the working space has been carried out by adjusting the distance between the camera and lens based on placed at different distances in front of the lens calibration models. A single rotatable light source for generating a locating light beam ( 6 ), with an incremental encoder ( 7 ) and stepper motor ( 8th ) is located to the left of the lens. The ultrasound couplings are carried out on gel blocks with embedded metal target structures, which correspond exactly to the dimensions of the calibration bodies in terms of their dimensions and positions and are located in the gel block exactly below the position which was taken by the calibration body during the calibration of the camera and the objective. The 8th shows in the upper part of the camera image of a recorded with the system puncture needle in the working space of the device according to the invention over the ultrasound image of the gel block (in the lower part of the figure). The sizes X1 and the angle Az can be determined directly from the camera image and displayed as a stitch projection in the ultrasound image. Following the superimposed stitch projection, the target structures, which run axis-parallel to the center beam of the camera with the puncture needle from a variety of different projections Xn and Az (n) can be safely hit safely, the passage of the stitch projection through the level of the sound and the insertion depth of the puncture needle remain unknown without the use of a tracking beam.

Investigations with the above-described camera and lens device and various light sources as a tracking light beam have now surprisingly shown that the puncture needle is well represented by the sweeping of the working space with a line laser in the image of the camera unit. If the sound probe inclines into the working space of the puncture, a line of light can be observed on the body surface, which is clearly interrupted or rejected by the puncture needle. The problem with spot locating beams that reflections from the body surface are difficult to differentiate from the desired reflections of the light beam through the puncture needle can thus be easily resolved by graphical analysis of the puncture needle induced distortion of the light line radiated onto the body. At the moment, in At the same time an interruption of the line of light radiated onto the skin and a reflection of the locating light beam from the puncture needle occur when the linear locating light beam passes over the puncture needle. The line of the tracking light beam irradiated onto the skin is thereby projected in the camera image to a different location than the reflection of the light from the surface of the puncture needle.

Furthermore, both small punctiform markings pushed onto the puncture needle and small dents driven into the needle surface appear as very characteristic distortions of the light line. With precise calibration of the lens and camera unit, known straight course of the puncture needle and sufficiently accurate measurement of the angle of incidence α of the line laser resolutions of the puncture needle structure and the needle position can be achieved in subpixel dimensions of the camera unit. Algorithms suitable for the calculations are known to those skilled in light-section methods for the three-dimensional optical detection of three-dimensional bodies. For example, the algorithms of the OpenCV, Qt and IVT program libraries can be used for the device according to the invention.

The light line is inventively taken by a lens and a camera that brings the entire working space of the ultrasound puncture axis parallel to the center beam of the camera for display. Experiments with simple non-axis parallel projecting lens systems show that when the needle is placed in the margins of the working space and in cases where the puncture is directed towards the line laser, precise data on the position of the needle can no longer be measured and calculated.

Non-axis parallel to the center beam imaging lenses have advantages in the reproduction of driven into the puncture needle or milled marker features. Advantageously, therefore, both camera systems can be installed simultaneously in the navigation system. In this case, the installation of a camera recording at a wider angle proves to be particularly advantageous, as an additional recording system rotating with the tracking light. Although the difficulty of missing spatial resolution can be partially met by imaging the working space using a plurality of camera systems spaced apart on the X axis of the sound baffle and / or two equally arranged line lasers. The measuring cycles of the system, however, lengthen considerably when using two line lasers. The use of multiple camera systems is generally associated with increased computational effort.

The use of line lasers as locating light beam ensures that the puncture needle is not only illuminated at individual punctual sections, as is the case with the use of punctiform light beams, but is detected in the longer course of the light beam. This only allows the puncture needle for calculating the penetration depth by small markers to make different. As a marker, this all measures to change the light reflection properties of the puncture needle into consideration. This can be accomplished by shading (overpainting), by engraving (very small densely spaced refractive lines), by deforming the surface (for example, by small dents driven into the needle surface, and by grinding in small (reflecting mirror planes).

In a further embodiment, small marking bodies, advantageously spherical rotational bodies are pushed, which have a small bore for receiving the puncture needle ( 1 . 3.1 . 3.2 ). Of these deferred marking bodies, one in the region of the syringe attachment piece of the needle can be firmly connected to the latter ( 1 . 3.1 ) and a second displaceable marker body are closer to the needle tip with respect to the first marker body ( 1 . 3.2 ). By deeper insertion of the needle, the front marker body can be pushed backwards by contact with the body surface. Advantageously, the front marker body may be connected by a spacer to the rear part of the needle; Particularly advantageously, the spacer has a hinge mechanism ( 9 3.3 ), which locks the front marker body in position until the locking is released by contact of the front marker body with the body surface, and the marker body by a retraction device, for example, a spring ( 9 . 3.5 ) is pulled back to a fixed position.

In a further embodiment, the marking body can be carried out so that they are slightly under pressure of the front marker body ( 1 3.2 ) on the body surface of the needle and fall down. The 9a shows a longitudinal sectional view of an exemplary embodiment of the puncture needle with deferred marking bodies ( 3.2 . 3.1 ). The 9b shows the front marker body ( 3.2 ) in the cross-sectional image. The front marker body ( 3.2 ) is equipped with a hinge mechanism ( 3.3 ) with the rear marker body ( 3.1 ) connected. When pressing the front marker body ( 3.2 ) on the skin becomes the hinge joint, by a lever ( 3.4 ) pushed up or folded down. This allows the effect of the spring ( 3.5 ) the up contractively moving arms of the hinge. The hinge joint folds up, pulling the front marker body ( 3.2 ) to the rear. The exact position to which the front marker body ( 3.2 ) can be locked by locking ( 3.6 ) are set to puncture needle or hinge joint.

An exemplary embodiment of a device according to the invention comprises:
A suitable and calibrated for imaging the working space in front of the sound probe camera, a lens consisting of lenses and / or mirrors, which images the subject image of the puncture space in front of the ultrasonic probe on the light sensors of the camera that all points of the working space of the puncture in a for Center beam of the camera parallel projection are imaged on the image plane of the camera ( 7 ).

At least one rotatably held linear locating light beam whose line curve is advantageously parallel to the Z axis of the Schalllotung, and its pivot point is particularly advantageous on the input plane of the optical lens system for axis-parallel representation of the working space.

Means for rotating the linear locating light beam and means for measuring the angle of the irradiated locating light beam to the X-axis of the coordinate system of the Schalllotung (incremental encoder).

Means for aspirating and smoothing the sterile cover of the sterile acoustic probe sheath to the apertures provided in front of the camera and lenses for the passage of the light and the exit ports of the detection beam.

A computer unit (PC), which contains information from the camera, the means for measuring the angle of the irradiated linear tracking light beam (incremental unit), the sound probe, and drives the motor of the rotatably held linear locating light beam.

Puncture needles marked by markings; or puncture needles, which are characterized by at least 2 deferred rotation bodies (i., balls), wherein the front marking body closest to the needle tip can be moved to the rear end of the needle during insertion of the needle; and a hinge mechanism that pulls the front marker body backward upon contact with the skin.

A kit containing the device according to the invention as well as puncture needles whose surface contour is characterized by dents. Puncture needles in whose surface contour very small closely adjacent grooves were engraved. A cover sheet having a different color from the line laser described above and the light beam emitted from the laser is adsorbed. A translucent sterile sheath into which the sound probe and the device according to the invention for ultrasonic navigation can be inserted, which can be sealed after introduction of the sound probe to the outside and which contains a hose open to the sound probe, which is connected to a Absaugvoririchtung (film and suction are in 1 not shown). A defined calibration image on the sterile cover foil of the puncture site.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• MAECKEN et al. 2007 [0001]
• Chan et al. (2005) [0003]
• Najafi and Rohling (2011) [0003]

Claims (10)

Device for determining the position of a puncture needle in the working space of an ultrasound probe with at least one camera and illuminants, characterized in that the puncture needle carrying optical markings is swept by a linear locating light beam rotated by a motor from a center point of the camera with at least one linear locating light beam rotated by a motor, and the light reflected by the puncture needle is picked up by an objective which projects the countergeneral points in the working space parallel to its center ray onto corresponding pixels of the camera, the image information of the camera and the angle of incidence of the linear locating light beam being supplied together with the ultrasound image to a processor unit which is the stitch projection, with X1 and AZ, the intersection of the stitch projection with the level of the Schalllotung, and the penetration depth of the needle together with the ultrasound image for display to be brought. Apparatus according to claim 1, characterized in that the locating light beam is punctiform. Device according to claims 1 and 2, characterized in that at least one camera brings the working space with a lens for display, which does not parallel to the center beam of the camera images the Gegengenstandspunkte of the working space. Device according to one or more of the preceding claims, characterized in that the puncture needle is optically marked by changing its surface. Device according to the preceding claim, characterized in that small grooves or depressions are chiselled or driven into the puncturing needle. Device according to one or more of the preceding claims, characterized in that small marking bodies, advantageously spherical rotary bodies are pushed onto the puncture needle having a small bore for receiving the puncture needle, wherein a rear of this deferred marking body in the region of the syringe attachment piece of the needle with this fixed is connected and a second displaceable marker body is closer to the needle tip with respect to the first marker body. Device according to one or more of the preceding claims, characterized in that a hinge mechanism holds the front marking body in a fixed position and pulls it backwards on contact with the skin. Device according to one or more of the preceding claims, characterized in that the sound probe is introduced into a translucent sterile sheath, which can be sealed to the outside after insertion of the sound probe and which contains a tube open to the sound probe, which is connected to a suction device. Device according to one or more of the preceding claims, characterized in that the data of the ultrasonic soldering together with the data of the camera unit and the angles measured with a device for measuring the angle of incidence of the locating light beam are fed to a computer unit which controls the motor of the locating light beam and the data to the Stichprojektion together with the ultrasound image on a Bidlschirm represents. A kit containing the device according to the invention as well as puncture needles whose surface contour is characterized by dents. Puncture needles in whose surface contour very small closely adjacent grooves were engraved. A cover sheet having a different color from the line laser described above and the light beam emitted from the laser is adsorbed. A translucent sterile sheath into which the sound probe and the inventive device for ultrasonic navigation can be introduced, which can be sealed after introduction of the sound probe to the outside and which contains a tube open to the sound probe, which is connected to a suction device, a defined calibration image on the sterile cover foil of the puncture site.

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