JP2018187171A - Registration marker and utilization program for registration marker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a design of a registration marker, enabling a coordinate system of a robot to be accurately aligned with a coordinate system of a medical image on a photographed medical image, and to provide an image processing and calculation means for aligning the coordinate systems of both robot and medical image.SOLUTION: The registration marker is a structure made of resin material. The registration marker comprises a base 2, and oblique prismatic bodies 3, 4, 5, 6 each of which is a cuboid, extends in a direction perpendicular to the base 2 and is installed on the base 2a at a prescribed inclination. The base 2 may have a hole for connection with other equipment. A target surface serving as a reference plane of a marker can be identified correctly with respect to the CT imaging reference surface coordinate system by referring to quadrangles 14, 15, 16, 17 shown in a sectional drawing of the oblique prismatic bodies 3, 4, 5, 6, and thereby the reference axis of the image can be determined correctly in an image photographed by CT.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a registration marker for operating a robot on a medical image, and a computer program used when a medical image photographed using the registration marker is processed by a computer.

  There is a treatment in which a surgical robot is operated using a medical image obtained from a medical imaging device such as CT or MRI as a guide. For example, when a puncture treatment such as biopsy or drug injection is performed on a cancer tumor, the position of the tumor is confirmed with a medical imaging device, and the puncture position and angle are determined based on a medical image. In order to move the end effector of the surgical robot that holds the needle to a precisely specified position / angle, it is necessary to accurately match (register) the acquired medical image and the three-dimensional coordinate system of the end effector of the robot. . If the coordinate system is deviated, the coordinate system is deviated from the designated position on the image, and there is a possibility that the accuracy of puncture will be reduced and interference with other devices may occur.

For this purpose, for example, it is necessary to accurately calculate the position and orientation of the end effector and the reference position and orientation of the image based on CT image data captured by CT. In order to accurately calculate the position of the end effector, it is necessary to photograph the registration marker attached to the end effector.
The registration marker calculates the position / angle of the marker from the obtained two-dimensional image group. Not only robot registration but also medical imaging markers for position acquisition have been proposed. For example, the marker of Patent Document 1 is composed of a base formed of a non-contrast agent and three spheres, and constructs a three-dimensional image from the captured CT image and specifies a reference point on the captured image. Is possible. Regarding the CT image and robot registration method, Patent Document 2 proposes a method using a laser marker irradiated from CT.

JP 2009-142561 A US Pat. No. 7,747,927

  By the way, the accuracy required for registration of a robot and CT images in puncture is very high. In particular, a puncture treatment for a deep body tumor requires a position error of 0.5 mm or less and an angle error of 1 ° or less. In the case of the above-mentioned Patent Document 1, an attempt is made to construct a three-dimensional image from a group of two-dimensional images and specify the position of the marker of the sphere. However, the use of voxel data and spheres that are difficult to detect accurately are handled. Therefore, highly accurate correction is difficult. In the case of Patent Document 2, registration is performed using a visible light laser as a reference. However, since the width of the marker laser irradiated from the CT is about 2 mm, it is considered that an error will occur.

  Also, the time required for registration and the installation cost are important. In the case of the above-mentioned patent document 1, it is assumed that correction calculation takes time because it is necessary to process a three-dimensional image. In the case of the above-mentioned Patent Document 2, the laser installation position and the positional relationship with the bed differ for each CT, which is not desirable from the viewpoint of versatility.

  Accordingly, the present invention provides a registration marker having a geometric shape capable of calculating the position / angle of the robot end effector with respect to the reference plane from the photographed two-dimensional CT image group, and the registration for correcting the position / angle of the robot from the calculation result. The purpose is to provide a management program.

  (1) The registration marker of the present invention is provided in a vertical plane extending in a normal direction of a reference plane including the base and a reference plane including the base, the base being set in parallel with the plane for taking a medical image. An oblique prism body extending at a predetermined gradient with respect to the base is provided, and the base and the oblique prism body are registration markers formed of a material that can be contrasted by a medical imaging apparatus.

  (2) The registration marker of the present invention extends in a normal direction of a base installed in a parallel positional relationship with a plane for taking a medical image and a reference plane including the base, and is not parallel to each other A registration unit formed of a material that can be contrasted by a medical imaging apparatus, and the base unit and the oblique column body are provided with an oblique column body extending at a predetermined gradient with respect to the base in a plurality of vertical planes. It is a marker.

  (3) The registration marker of the present invention can measure an angle and / or displacement with respect to a plane on which a medical image is taken, and the medical image may include a CT image, an MRI image, and a fluoroscope image.

  (4) The registration marker of the present invention includes an oblique column body extending at a predetermined gradient with respect to the base described in (1) above in the vertical plane described in (1), and parallel to the vertical plane. Alternatively, an oblique prism body extending with a predetermined gradient with respect to the base described in (1) above may be provided in a non-parallel plane.

  (5) The registration marker of the present invention may be capable of measuring both the angle in two different directions with respect to the plane on which the medical image is taken and the position in the direction perpendicular to the base described in (1) above.

(6) The utilization program of the present invention is a program for utilizing the registration marker according to any one of (1) to (5) above,
Processing to store in advance two or more oblique prisms and store their arrangement, dimensions, positional relationship to the robot and other similar devices, the shape change of the parallelogram appearing in the cross section of the CT image, and the resolution of the CT image When,
Image display processing for storing a parallelogram geometric amount that is a cross-section of the oblique column body that appears in CT image data that is captured by setting the registration marker at a predetermined position in a robot and other similar devices When,
This is a registration marker utilization program characterized by including:

(7) The utilization program of the present invention is a program for utilizing the registration marker according to any one of (1) to (6) above,
A process of calculating and storing a rotation angle of the reference plane of the registration marker according to (1) with respect to the CT imaging reference plane coordinate system from the stored geometric amount;
An operation command such that the reference plane of the registration marker and the CT imaging reference plane coordinate system are in parallel with the robot and other similar devices according to the stored rotation angle;
This is a registration marker utilization program characterized by including:

(8) The utilization program of the present invention is a program for utilizing the registration marker according to any one of (1) to (6) above,
In the CT image obtained again in a state where the reference plane coordinate system of the registration marker and the CT imaging reference plane coordinate system are parallel by the operation command, the registration marker is stored by the geometric amount stored by the program described in (5) above. A process for calculating and storing a distance in which the CT imaging reference plane of the reference plane is separated in a direction perpendicular to the coordinate plane;
The operation command such that the reference plane of the registration marker and the CT imaging reference plane coordinate system match the robot according to the stored distance,
This is a registration marker utilization program characterized by including:

  ADVANTAGE OF THE INVENTION According to this invention, the marker and program which enable accurate registration of a medical image and a robot simply and with high precision can be provided, and it can contribute to an effective treatment in a clinical field.

1 is a front view of a registration marker 1 according to an embodiment of the present invention. It is the figure which showed two medical image photography cross sections parallel to the base 2 in the side view of the marker 1 with the straight line. It is the figure which showed two medical image photography cross sections perpendicular | vertical with respect to the side surface to the side view of the marker 1 with the straight line. It is a rear view of the registration marker 1 which concerns on embodiment of this invention. 1 is an isometric view of a registration marker 1 according to an embodiment of the present invention. It is sectional drawing of the marker 1 when a medical image is image | photographed by the plane shown by the straight line 7 in FIG. 2 or FIG. It is sectional drawing of the marker 1 when a medical image is image | photographed by the plane shown by the straight line 8 in FIG. It is sectional drawing of the marker 1 when a medical image is image | photographed by the plane shown by the straight line 9 in FIG. It is a follow chart for demonstrating the processing content of the program which concerns on one Embodiment of this invention.

  The registration marker according to the present invention is composed of oblique prisms arranged in four directions, and has a major feature that the shape depicted in the CT image changes due to the deviation of the position / angle of the robot with respect to the CT imaging reference plane. is there. The geometric amount of the cross-sectional shape of the marker is grasped from the drawn shape using image processing. Since the cross-sectional shape is composed of straight lines, the error in image processing is smaller than that of a circular shape. Further, by arranging the oblique prisms in all directions, it is possible to calculate both the positional and angular deviations with the same marker. Furthermore, trigonometric functions are used for the correction calculation in the angle calculation. By using an oblique prism instead of a right prism, it is possible to calculate a minute angle deviation near the CT imaging reference plane with high accuracy. .

  The registration program according to the present invention obtains the geometric amount of each vertex and each side of the cross-sectional shape of the marker depicted in the captured CT image by image processing, and from the geometric amount, the position of the marker relative to the CT imaging reference plane This is a program that calculates the angle deviation and instructs the position and angle of the robot to match the CT imaging reference plane based on the calculation result, and inputs basic data such as marker size and CT scan settings to initialize the program. The step of obtaining the geometrical amount of the marker cross-sectional shape from the acquired CT image group, calculating the deviation of the marker position / angle with respect to the CT imaging reference plane, and adjusting the position / angle of the robot from the calculation result And causing the computer to execute the steps.

  Hereinafter, embodiments of a registration marker and a registration marker utilization program according to the present invention will be described in detail with reference to the drawings.

  The registration marker of this embodiment (hereinafter simply referred to as “marker”) is attached to a predetermined part of the robot and used to recognize the position of the predetermined part. The predetermined portion may be an end effector of a robot. The robot described above is juxtaposed with the medical imaging apparatus and used together with the medical imaging apparatus. A medical imaging apparatus is an apparatus that captures a medical image such as a tomogram of a patient. Examples of medical imaging devices include CT devices, MRI devices, and fluoroscope devices. That is, examples of the medical image include a CT image, an MRI image, and a fluoroscope image.

  The marker of the present embodiment includes a prismatic body made of a contrast material. In the usage state of the marker, the prismatic body extends in a direction inclined with respect to the head-to-tail direction of the medical imaging apparatus. Note that the extending direction of the prismatic body means the extending direction of the column axis of the prismatic body. Further, when the robot is used, the prismatic body is located within the imageable area of the medical imaging apparatus. Since the prismatic body is made of a contrast material, a tomogram of the prismatic body can be imaged by a medical imaging apparatus. A resin may be used as the contrast material. Further, the entire marker may be integrally formed of a contrast material.

  In the following description, the head-to-tail direction of the medical imaging apparatus may be referred to as the Z direction, the vertical direction as the Y direction, and the direction orthogonal to both the Z direction and the Y direction as the X direction. A plane orthogonal to the Z direction may be referred to as an XY plane, a plane orthogonal to the Y direction may be referred to as a ZX plane, and a plane orthogonal to the X direction may be referred to as a YZ plane. Further, rotation around an axis parallel to the Z direction may be referred to as θZ rotation, rotation around an axis parallel to the Y direction may be referred to as θY rotation, and rotation around an axis parallel to the X direction may be referred to as θX rotation.

  In the medical imaging apparatus, a tomographic image (medical image) of a tomogram parallel to the XY plane is obtained. At this time, a cross section of the prismatic body appears in the image of the tomography crossing the prismatic body. The state of this cross section differs depending on the positional relationship between the real fault and the real marker. Therefore, if a predetermined calculation is performed based on the cross-sectional state of the prismatic body that appears in the tomographic image, the positional relationship between the real fault and the real marker can be derived. Here, the “section state” may include the position of the section in the translational direction on the tomographic image, the position of the section in the rotation direction, the shape of the section, and the like. When a plurality of cross sections appear, the “cross-section state” may include a positional relationship between the plurality of cross sections. Further, the “positional relationship” may include a positional relationship in the translation direction and a positional relationship in the rotation direction.

  Since the positional relationship between the tomography and the marker can be derived as described above, the positional relationship between the medical imaging apparatus and the marker can be recognized. In addition, the positional relationship between the patient and the robot placed on the medical imaging apparatus can be recognized.

  Although the number of prisms provided in the marker may be one, it is more preferable if it is plural. In this case, the positional relationship between the tomogram and the marker can be recognized in more detail based on the state of the plurality of cross sections appearing on the tomographic image. Alternatively, the positional relationship can be recognized with high accuracy. Moreover, it is preferable that the some prismatic body with which a marker is provided is extended in the direction which is not mutually parallel.

  As an example of the marker as described above, a perspective view of the marker 1 is shown in FIG. The marker 1 includes a flat rectangular base 2. The base 2 is provided with a plurality of connection holes. The marker 1 is fixed to the end effector of the robot by screwing using a connection hole or the like. The marker 1 may be used in such a posture that the base 2 is substantially parallel to the XY plane. In the following description, X, Y, and Z are used in correspondence with the posture of the marker 1 such that the base 2 is parallel to the XY plane. In addition, it is assumed that two of the four sides of the rectangle presented by the base 2 extend in the X direction and the other two sides extend in the Y direction.

  The marker 1 includes four oblique pillars 3, 4, 5, 6 erected on the edges of the four sides of the base 2. The base 2 and the four oblique columns 3, 4, 5, 6 may be integrally formed. The four oblique columns 3, 4, 5, 6 all have the same shape. The oblique column 3 and the oblique column 5 are provided at the edges of the sides of the base 2 facing each other. The oblique column 4 and the oblique column 6 are provided at the edges of the sides of the base 2 facing each other. All the oblique columns 3, 4, 5, 6 extend in a direction inclined with respect to the direction orthogonal to the base 2. Specifically, the column axes of all the oblique columns 3, 4, 5, 6 intersect with the XY plane at an angle of 45 °.

  When the marker 1 is projected onto the ZX plane, the extending direction of the oblique prism 3 and the extending direction of the oblique prism 5 are line-symmetric with respect to an axis parallel to the Z direction. When the marker 1 is projected onto the ZX plane, the extending direction of the oblique prism 4 and the extending direction of the oblique prism 6 are both parallel to the Z direction. When the marker 1 is projected onto the YZ plane, the extending direction of the oblique column 4 and the extending direction of the oblique column 6 are line-symmetric with respect to an axis parallel to the Z direction. When the marker 1 is projected onto the YZ plane, the extending direction of the oblique prism 3 and the extending direction of the oblique prism 5 are both parallel to the Z direction.

  According to the marker 1 as described above, four cross sections of each of the oblique prisms 3, 4, 5, 6 appear in the tomographic image of the tomogram parallel to the XY plane. An example of four cross sections of each of the oblique prisms 3, 4, 5, 6 appearing in the tomographic image is, for example, a cross section 10, 11, 12, 13 as shown in FIG. Based on the states of the four cross sections, the positional relationship between the real fault and the real marker 1 can be recognized by a predetermined calculation. As a result, the positional relationship between the medical imaging device and the marker 1 can be recognized, and a registration process for accurately matching the three-dimensional coordinate system between the medical image and the robot is possible.

  Hereinafter, the detailed configuration of the marker 1 will be described with reference to the drawings, and the utilization program of the marker 1 will be described in detail.

FIG. 1 is a front view of a registration marker (hereinafter simply referred to as “marker”) 1 according to an embodiment of the present invention, FIG. 2 and FIG. 3 are side views of the marker 1, and FIG. FIG. 5 and FIG. 5 are isometric views of the marker 1.
1 to 5, the marker 1 has a plate-like base 2 formed of a resin material, for example, PEEK resin.

  This marker 1 is attached to the end effector of the robot and used when the robot and the coordinate system of the CT image are matched. The base 2 of the marker 1 has a square shape in plan view and has a mounting hole for each device.

  The marker 1 includes oblique prisms 3, 4, 5, and 6 that are arranged so that the end portions thereof coincide with the side surfaces of the base 2 and project in the planar direction. Each oblique column 3, 4, 5, 6 is made of a resin material, for example, PEEK resin.

In this embodiment, each oblique column 3, 4, 5, 6 is inclined at 45 ° along the side surface of the base 2. Further, the marker 1 is integrally molded by cutting out PEEK resin, for example, and the base 2 and the oblique prisms 3, 4, 5, 6 are integrated.
In addition, it replaces with the integral shaping | molding by cutting, and it is good also as a structure which piles up and adhere | attaches each diagonal column 3, 4, 5, 6 on the four side surfaces of the base 2. FIG.

  FIG. 6 is a diagram showing a cross section when the marker 1 shown in FIG. 5 is positioned in parallel to the CT imaging reference plane and the CT is imaged on the reference plane of the marker, that is, the imaging plane 7. At this time, as shown in FIG. 6, the cross section of the marker 1 is displayed with four parallelogram cross sections 10, 11, 12, and 13 which are cross sections of the oblique prisms 3, 4, 5, and 6.

  FIG. 7 is a view showing a cross section of the marker 1 when the CT shown in FIG. 5 is imaged on the imaging surface 8 inclined with respect to the CT imaging reference plane. At this time, as shown in FIG. 7, the cross section of the marker 1 is displayed with four parallelogram cross sections 14, 15, 16, and 17 that are cross sections of the respective oblique prisms 3, 4, 5, and 6. The CT of the marker 1 is calculated from the ratio of the lengths of the long sides of the displayed parallelogram sections 14, 15, 16, and 17 with the length of each long side of the parallelogram sections 10, 11, 12, and 13 as a reference. An angle from the imaging reference plane is calculated. At this time, by using an oblique column of 45 °, it is possible to calculate with a small error even for an imaging surface with a small angle of inclination near the CT imaging reference surface.

  FIG. 8 is a diagram showing a cross section of the marker 1 when CT is imaged on the imaging surface 9 obtained by translating the marker 1 shown in FIG. 5 with respect to the CT imaging reference plane. At that time, as shown in FIG. 8, four parallelogram sections 18, 19, 20, and 21, which are sections of the respective oblique prisms 3, 4, 5, and 6, are displayed as the section of the marker 1. The position of the marker 1 from the CT imaging reference plane is determined from the distance of the center position of the displayed parallelogram sections 18, 19, 20, and 21 with the center position of the parallelogram sections 10, 11, 12, and 13 as a reference. calculate.

FIG. 9 is a flowchart for showing a flow of processing contents of a program for utilizing the marker 1 according to the embodiment of the present invention. Next, the contents of the program for utilizing the marker 1 will be described with reference to FIG.
First, the marker 1 is attached to the end effector of the robot and moved to a position where CT imaging is possible. When the program starts, it is first determined whether or not the standard dimension of the marker 1 is stored. If the standard dimension of the marker 1 is not stored, input of the standard dimension is required.
The standard dimensions of the marker 1 are the lengths of the four sides of the base 2 of the marker 1 described with reference to FIG. 1 and the external dimensions of the oblique pillars 3, 4, 5, 6.

  Next, CT imaging is performed and image data is input. At that time, it is determined whether or not the resolution information of the CT image is stored, and if the resolution of the CT image is not stored, the input of the resolution is required.

  Then, after that, a CT image is displayed, from which the geometric amount of the cross-sectional shape of the marker 1 is acquired using image processing, and the rotation angle of the marker 1 with respect to the CT imaging reference plane is calculated. Using the calculation result, the robot is instructed to move the end effector of the robot so that the marker reference plane and the CT imaging reference plane are parallel.

  Then, another CT image is taken and data is input. The geometric amount of the cross-sectional shape of the marker 1 is acquired from the displayed CT image using image processing, and the distance of the reference surface of the marker 1 with respect to the CT imaging reference surface is calculated. Using the calculation result, the robot is instructed to move the end effector of the robot so that the center point of the marker reference plane matches the center point of the CT imaging reference plane.

  Finally, the coordinate system of the CT imaging reference plane is coordinate-converted and stored in the robot coordinate system via the positional relationship between the marker 1 and the robot. In other words, the pixel position designated on the CT image is converted as three-dimensional position information of the robot coordinate system.

DESCRIPTION OF SYMBOLS 1 Registration marker 2 Base 3, 4, 5, 6 Inclined prism 7 Imaging surface 8 when imaged on the reference plane of the marker Imaging surface 9 in which the imaging surface 7 moves in a direction perpendicular to the base 1 Imaging surface 7 is the base Imaging surface 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 moved in a direction perpendicular to 1 Parallelogram section

Claims (8)

  A base installed in a positional relationship that is parallel to the plane for taking a medical image, and a predetermined plane with respect to the base in a vertical plane extending in a normal direction of a reference plane including the base A registration marker comprising an extending oblique prism body, wherein the base and the oblique prism body are made of a material that can be contrasted by a medical imaging apparatus.   A base installed in a parallel position relative to a plane for taking a medical image; and a plurality of vertical planes extending in a normal direction of a reference plane including the base and not parallel to each other A registration marker formed of a material that can be contrasted with a medical imaging apparatus.   3. The resist according to claim 1, wherein an angle and / or displacement with respect to a plane on which the medical image is taken can be measured, and the medical image includes a CT image, an MRI image, and a fluoroscope image. Marker.   The oblique prism body extending at a predetermined gradient with respect to the base according to claim 1 in the vertical plane according to claim 1, and the non-parallel plane not parallel to the vertical plane according to claim 1. The registration marker of any one of Claims 1-3 provided with the oblique column body extended | stretched with the predetermined gradient with respect to a base.   The resist according to any one of claims 1 to 4, wherein both the angle in two different directions with respect to a plane for taking a medical image and the position in a direction perpendicular to the base according to claim 1 can be measured. Marker. A program for utilizing the registration marker according to any one of claims 1 to 5,
Processing to store in advance two or more oblique prisms and store their arrangement, dimensions, positional relationship to the robot and other similar devices, the shape change of the parallelogram appearing in the cross section of the CT image, and the resolution of the CT image When,
Image display processing for storing a parallelogram geometric amount that is a cross-section of the oblique column body that appears in CT image data that is captured by setting the registration marker at a predetermined position in a robot and other similar devices When,
A registration marker utilization program characterized by including: A program for utilizing the registration marker according to any one of claims 1 to 6,
A process of calculating and storing a rotation angle of the reference plane of the registration marker according to claim 1 with respect to the CT imaging reference plane coordinate system from the stored geometric amount;
An operation command such that the reference plane of the registration marker and the CT imaging reference plane coordinate system are in parallel with the robot and other similar devices according to the stored rotation angle;
A registration marker utilization program characterized by including: A program for utilizing the registration marker according to any one of claims 1 to 6,
6. The CT image acquired again in a state in which the reference plane coordinate system of the registration marker and the CT imaging reference plane coordinate system are parallel by the operation command, according to the geometric amount stored by the program according to claim 5, Processing for calculating and storing the distance at which the CT imaging reference plane of the reference plane is separated in a direction perpendicular to the coordinate plane;
The operation command such that the reference plane of the registration marker and the CT imaging reference plane coordinate system match the robot according to the stored distance,
A registration marker utilization program characterized by including: