CN112043377A - Method and system for ablation path planning assisted by ultrasound field simulation in any CT slice - Google Patents

Abstract

The ultrasound visual field simulation auxiliary ablation path planning method and system for any section of CT comprises the following steps: (1) acquiring a CT image, and reconstructing data of bones, body surfaces, livers, tumors and blood vessels; (2) selecting the position of an ultrasonic probe in the intercostal space parallel to the right season, generating a CT section passing through the center of the tumor, and ensuring that the section does not intersect with the ribs; (3) cutting and converting the CT section to simulate the actual abdominal ultrasonic visual field range; (4) generating a needle insertion path in an ultrasonic visual field plane, wherein the path needs to meet a constraint condition not intersecting with a blood vessel; (5) generating a simulated thermal field; and (4) judging the spatial coverage relation between the thermal field and the tumor, if the thermal field and the tumor are not completely covered, acquiring the parallel section of the plane along the long axis direction of the coronary tumor, and executing the step (3) until the thermal field completely covers the tumor.

Description

Method and system for ablation path planning assisted by ultrasound field simulation in any CT slice

technical field

The invention relates to the technical field of medical image processing, in particular to a CT arbitrary section ultrasonic field of view simulation-assisted ablation path planning method, and a CT arbitrary section ultrasonic field of view simulation-assisted ablation path planning system.

Background technique

Compared with surgery, ultrasound-guided microwave and radiofrequency ablation is a new method for local treatment of liver cancer. This technology is guided by ultrasound, and through microwave or radiofrequency needles, electromagnetic waves are converted into heat energy, and the energy is transferred to the tumor area to achieve localized tumor performance. Complete coagulation necrosis has been recommended as the first-line treatment for small hepatocellular carcinoma by many international guidelines such as NCCN and BCLC. However, ultrasound-guided ablation of liver cancer is a comprehensive process involving a variety of knowledge and technical links. Although this technology is widely used, there are still some important basic scientific problems to be solved.

Precision is the ultimate goal of tumor ablation therapy. Individualized three-dimensional space needle insertion path planning is an essential means to achieve precise ablation. At present, 3D ablation path planning is based on the patient's preoperative CT or MR images, and a 3D model is established, so that planners can clearly observe the adjacent relationship around the tumor in 3D space, design a precise needle insertion path to avoid important structures such as blood vessels, and minimize damage. , The minimum number of needle injections to achieve the best therapeutic effect. However, preoperative planning based on CT images often has a large deviation from the intraoperative puncture path guided by ultrasound, and this defect has become one of the challenges of accurate ablation.

3D space display is the advantage of 3D space needle insertion planning, but it also has major limitations. Specifically, the CT observation field of view is quite different from the intraoperative real-time ultrasound field of view, resulting in path planning and actual ultrasound guidance only through CT images. Inconsistent operability of lower needles ultimately leads to a disconnect between surgical planning and actual execution. At present, the intraoperative navigation technology of multimodal image fusion based on magnetic positioning technology can realize the fusion of CT and ultrasound images, but it needs to be combined with a magnetic positioning device, and the intraoperative needle insertion process still needs to rely on the preoperative needle insertion path planning. In addition, the simulated ultrasound method can establish three-dimensional volume ultrasound based on the real ultrasound acquisition of the region of interest, and display the tomographic image according to the virtual probe position, but the volume ultrasound acquisition process is complicated and difficult to obtain, resulting in its poor practicability. In recent years, ultrasound image simulation methods based on CT data, such as the ultrasound reflection model method, all focus on the simulation of image imaging modes and image resolution. Therefore, based on the above problems, there is an urgent need for a visual preoperative planning system based on CT, which can integrate CT and intraoperative ultrasound image visual field display features in three-dimensional space, and improve the operability and accuracy of preoperative planning.

SUMMARY OF THE INVENTION

In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a CT arbitrary section ultrasonic field of view simulation-assisted ablation path planning method, which focuses more on the simulation with both CT image resolution and ultrasonic imaging field of view, so that In the preoperative 3D planning process, the needle insertion is planned based on the CT image and the actual perspective of the doctor during the operation, so as to facilitate the rational planning of the operation by the imaging doctor who is not an ultrasound professional, and improve the practicability and accuracy of the preoperative planning.

The technical scheme of the present invention is: this CT arbitrary section ultrasonic field simulation auxiliary ablation path planning method, which comprises the following steps:

(1) Obtain CT images and reconstruct bone, body surface, liver, tumor, and blood vessel data;

(2) Select the position of the ultrasound probe parallel to the right intercostal space, and generate a CT section through the center of the tumor to ensure that the section does not intersect with the ribs;

(3) The CT section is cut and transformed to simulate the actual abdominal ultrasound field of view;

(4) In the plane of the ultrasound field of view, a needle insertion path is generated, and the path needs to meet the constraint condition that it does not intersect with the blood vessel;

(5) Generate a simulated thermal field; determine the spatial coverage relationship between the thermal field and the tumor, if not completely covered, obtain a parallel section of the plane along the long axis of the coronal tumor, and perform step (3) until the thermal field completely covers the tumor.

The present invention obtains CT images, performs three-dimensional reconstruction, generates CT cross-sections passing through the center of the tumor, cuts and transforms the CT cross-sections, simulates the actual abdominal ultrasound field of view, generates a needle insertion path within the ultrasound field of view, generates a simulated thermal field, and more It focuses on the simulation of both CT image resolution and ultrasound imaging field of view, so that in the process of preoperative 3D planning, the needle insertion is planned based on the CT image while referring to the doctor's actual viewing angle during the operation, so as to facilitate the rational planning of the operation by the imaging doctor who is not an ultrasound professional. Improve the feasibility and accuracy of preoperative planning.

Also provided is a CT arbitrary slice ultrasound visual field simulation-assisted ablation path planning system, which includes:

Data import module, which is configured to acquire CT images;

Reconstruction modules configured to reconstruct bone, body surface, liver, tumor, blood vessel data;

A CT section generation module configured to select an ultrasound probe position parallel to the right intercostal space, and to generate a CT section through the center of the tumor, ensuring that the section does not intersect the ribs;

A simulated ultrasound field of view module, which is configured to cut and transform the CT section to simulate the actual abdominal ultrasound field of view;

A needle entry path generation module, which is configured to generate a needle entry path within the ultrasound field of view plane, and the path needs to satisfy the constraint condition that it does not intersect with the blood vessel;

The simulation thermal field generation module is configured to determine the spatial coverage relationship between the thermal field and the tumor. If the thermal field is not completely covered, a parallel section of the plane is obtained along the long axis of the coronal tumor, and the simulated ultrasound field of view module is executed until the thermal field completely covers the tumor. .

Description of drawings

FIG. 1 is a flow chart of a method for planning an ablation path assisted by ultrasound field simulation in any CT slice according to the present invention.

FIG. 2 is a flow chart of a specific embodiment of the method for planning an ablation path assisted by CT arbitrary slice ultrasound field simulation according to the present invention.

FIG. 3 is a schematic diagram of path planning according to the present invention.

Detailed ways

Image-guided minimally invasive techniques have become one of the hotspots in tumor treatment. In order to achieve precise tumor inactivation under the guidance of ultrasound images, 3D visualization preoperative planning is an essential method. However, preoperative planning based on CT images is often associated with ultrasound guidance. Therefore, the invention of CT three-dimensional images with ultrasound field of view is the key method to solve this problem.

As shown in Figure 1, this CT arbitrary slice ultrasound field simulation-assisted ablation path planning method includes the following steps:

(1) Obtain CT images and reconstruct bone, body surface, liver, tumor, and blood vessel data;

(2) Select the position of the ultrasound probe parallel to the right intercostal space, and generate a CT section through the center of the tumor to ensure that the section does not intersect with the ribs;

(3) The CT section is cut and transformed to simulate the actual abdominal ultrasound field of view;

(4) In the plane of the ultrasound field of view, a needle insertion path is generated, and the path needs to meet the constraint condition that it does not intersect with the blood vessel;

(5) Generate a simulated thermal field; determine the spatial coverage relationship between the thermal field and the tumor, if not completely covered, obtain a parallel section of the plane along the long axis of the coronal tumor, and perform step (3) until the thermal field completely covers the tumor.

The present invention obtains CT images, performs three-dimensional reconstruction, generates CT cross-sections passing through the center of the tumor, cuts and transforms the CT cross-sections, simulates the actual abdominal ultrasound field of view, generates a needle insertion path within the ultrasound field of view, generates a simulated thermal field, and more It focuses on the simulation of both CT image resolution and ultrasound imaging field of view, so that in the process of preoperative 3D planning, the needle insertion is planned based on the CT image while referring to the doctor's actual viewing angle during the operation, so as to facilitate the rational planning of the operation by the imaging doctor who is not an ultrasound professional. Improve the feasibility and accuracy of preoperative planning.

Preferably, in the step (1), CT equipment is used to scan the abdomen, to obtain DICOM (Digital Imaging and Communications in Medicine) images of preoperative CT, and to segment and three-dimensionally reconstruct relevant regions of interest.

Preferably, the step (2) includes the following sub-steps:

(2.1) Calculate the geometric center coordinates of the tumor based on the three-dimensional tumor model;

(2.2) Two points p1 and p2 were selected on the right body surface parallel to the intercostal space as the initial position of the probe, and the CT slice was determined in combination with the center point of the tumor.

Preferably, in the step (2.1), the calculation is realized by the following methods: calculating the mean value of the coordinates of the data points of the tumor body, or searching for the maximum point of the tumor diameter through a double-section loop iteration.

Preferably, the step (2.2) is implemented by a multi-plane reconstruction method.

Preferably, the step (3) includes the following steps:

(3.1) Using the probe model as an input parameter, obtain the ultrasonic transducer array width L in the probe, the conventional imaging angle θ during ultrasound surgery, the depth information H and the CT image resolution p;

(3.2) According to the position coordinates of the two points of the initial probe, an initial two-dimensional matrix M1(H, W) is generated on the CT slice, where W=2*H*sin(θ/2)+L*tan(θ/2), The starting point of the left line boundary of the ultrasonic fan is a[1, a], where a=int[H*sin(θ/2)-L(1-tan(θ/2))/2)/p], the left side of the right starting point b[1,b], where b=int[a+L/p], the coordinates of the end point of the left line of the ultrasound line boundary c[c,1], where c=int[(H*cos(θ/2)-L* (1-tan(θ/2))/tan(θ/2)/2)/p], the coordinates of the end point of the ultrasound right boundary d[c, d1], where d1=int[W/p];

(3.3) The radian boundary coordinates of the left side of the deep part of the fan shape are determined by [int[(h+k*radian(θ)/s/2)/p], k], where k=1, 2, 3...w/p/2 , the radian boundary coordinates of the right side are obtained from the symmetry information, and the radians of the shallow sector of the sector are calculated in the same way;

(3.4) Replace the pixel value outside the sector boundary of the M1 matrix with 0 to generate a matrix M2, which is an ultrasound field simulation matrix.

Preferably, the step (4) includes the following sub-steps:

(4.1) Take the right boundary point of the probe as the needle insertion point and the tumor center as the target point to generate the initial needle insertion path;

(4.2) Using the blood vessel V as the constraint condition, determine whether the path intersects with the blood vessel. If it intersects, rotate to the right by a certain angle with the center of the tumor as the center until it does not intersect the blood vessel, and determine the needle entry path N1 in this plane.

Preferably, the certain angle in the step (4.2) is 5°.

Preferably, in the step (5), according to the model of the ablation needle, a simulated thermal field is generated by taking the intersection of the path and the distal boundary of the tumor as the boundary point of the long axis of the thermal field, and the parameters of the thermal field are set according to the model of the ablation needle.

Those of ordinary skill in the art can understand that all or part of the steps in the method of the above-mentioned embodiments can be completed by instructing the relevant hardware through a program, and the program can be stored in a computer-readable storage medium, and the program can be stored in a computer-readable storage medium. During execution, it includes each step of the method in the above embodiment, and the storage medium may be: ROM/RAM, magnetic disk, optical disk, memory card, and the like. Therefore, corresponding to the method of the present invention, the present invention also includes a CT arbitrary slice ultrasound visual field simulation-assisted ablation path planning system, which is usually expressed in the form of functional modules corresponding to each step of the method. The system includes:

Data import module, which is configured to acquire CT images;

Reconstruction modules configured to reconstruct bone, body surface, liver, tumor, blood vessel data;

A CT section generation module configured to select an ultrasound probe position parallel to the right intercostal space, and to generate a CT section through the center of the tumor, ensuring that the section does not intersect the ribs;

A simulated ultrasound field of view module, which is configured to cut and transform the CT section to simulate the actual abdominal ultrasound field of view;

A needle entry path generation module, which is configured to generate a needle entry path within the ultrasound field of view plane, and the path needs to satisfy the constraint condition that it does not intersect with the blood vessel;

The simulation thermal field generation module is configured to determine the spatial coverage relationship between the thermal field and the tumor. If the thermal field is not completely covered, a parallel section of the plane is obtained along the long axis of the coronal tumor, and the simulated ultrasound field of view module is executed until the thermal field completely covers the tumor. .

A specific embodiment of the present invention will be described below.

As shown in Figure 2 and Figure 3, the path planning method of the present invention includes:

S1. Obtain CT images;

Abdominal scan was performed with CT equipment to obtain DICOM images of preoperative CT.

S2 segmentation to reconstruct bone, body surface, liver, tumor, blood vessel data;

Segment and 3D reconstruct relevant regions of interest.

S3. Select the position of the ultrasound probe parallel to the right intercostal space, and generate a CT section through the center of the tumor to ensure that the section does not intersect with the ribs;

First, based on the three-dimensional tumor model, calculate the geometric center coordinates of the tumor. This calculation can be achieved by various methods, such as calculating the mean value of the coordinates of the data points of the tumor body, or finding the maximum point of the tumor diameter through double-section cyclic iteration; on the right body surface Two points p1 and p2 were selected as the initial position of the probe for the parallel rib space, and the CT slice was determined in combination with the center point of the tumor. This calculation can be realized by a multi-plane reconstruction algorithm.

S4. Transform the CT section to simulate the fan-shaped field of view of abdominal ultrasound;

Taking the probe model as the input parameter, the width L of the ultrasonic transducer array in the probe, the conventional imaging angle θ in the ultrasound operation, the depth information H and the CT image resolution p are obtained; according to the position coordinates of the two points of the initial probe, the initial two points are generated in the CT slice. Dimensional matrix M1(H,W), where W=2*H*sin(θ/2)+L*tan(θ/2), the starting point a[1, a] of the left line boundary of the ultrasonic sector, where a=int [H*sin(θ/2)-L(1-tan(θ/2))/2)/p], left b[1,b] from the right starting point, where b=int[a+L/p] , the coordinates of the end point of the left line boundary of the ultrasound c[c,1], where c=int[(H*cos(θ/2)-L*(1-tan(θ/2))/tan(θ/2)/ 2)/p], the coordinates of the end point of the ultrasound right boundary d[c, d1], where d1=int[W/p]. The radian boundary coordinates of the left side of the deep sector of the sector are defined by [int[(h+k*radian(θ)/s/2)/p],k], where k=1,2,3...w/p/2, the right side The radian boundary coordinates are obtained from the symmetry information, and the radians of the shallow part of the sector are calculated in the same way. Then, replace the pixel values outside the sector boundary of the M1 matrix with 0 to generate a matrix M2, which is an ultrasound field simulation matrix.

S5. In the ultrasound field of view plane, generate a needle insertion path, and the path needs to satisfy the constraint condition that it does not intersect with the blood vessel;

Take the right boundary point of the probe as the needle entry point and the tumor center as the target point to generate the initial needle entry path; take the blood vessel V as the constraint condition to determine whether the path intersects with the blood vessel, and if it intersects, rotate to the right with the tumor center as the center A certain angle can be set as 5° as the rotation step, until it does not intersect with the blood vessel, and the needle entry path N1 of this plane is determined.

S6. Generate a simulated thermal field;

According to the type of ablation needle, a simulated thermal field is generated by taking the intersection of the path and the distal boundary of the tumor as the boundary point of the long axis of the thermal field, and the parameters of the thermal field can be set according to the type of ablation needle.

S7. Determine the spatial coverage relationship between the thermal field and the tumor at this level. If it is not completely covered, translate a path that satisfies the constraints on the plane until the thermal field completely covers the tumor.

According to the boundary coordinates of the thermal field and the spatial coordinates of the tumor, the relationship between the thermal field and the tumor is judged. If it is not completely covered, a path Nn that satisfies the constraints will be translated in the plane, and the translation step distance is set as the radius of the short axis of the thermal field until The thermal field completely covers the tumor.

Compared with ultrasonic simulation methods such as multimodal image fusion based on magnetic positioning technology and ultrasonic simulation technology, this method is simpler, more convenient and easier to implement. In line with the application purpose of the present invention, it focuses on the simulation of the range of the ultrasound imaging field of view, rather than the simulation of the spatial resolution of the ultrasound image, which is beneficial to the radiologists who are not professional in ultrasound to carry out reasonable spatial planning and treatment of tumors.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to the present invention The protection scope of the technical solution of the invention.

Claims (10)

1. CT arbitrary section ultrasound visual field simulation assisted ablation path planning method, is characterized in that: it comprises the following steps: (1) Obtain CT images and reconstruct bone, body surface, liver, tumor, and blood vessel data; (2) Select the position of the ultrasound probe parallel to the right intercostal space, and generate a CT section through the center of the tumor to ensure that the section does not intersect with the ribs; (3) The CT section is cut and transformed to simulate the actual abdominal ultrasound field of view; (4) In the plane of the ultrasound field of view, a needle insertion path is generated, and the path needs to meet the constraint condition that it does not intersect with the blood vessel; (5) Generate a simulated thermal field; determine the spatial coverage relationship between the thermal field and the tumor, if not completely covered, obtain a parallel section of the plane along the long axis of the coronal tumor, and perform step (3) until the thermal field completely covers the tumor. 2. The method for simulating assisted ablation path planning of CT arbitrary slices according to claim 1, characterized in that: in the step (1), a CT device is used to scan the abdomen to obtain the DICOM image of the preoperative CT, segment and 3D reconstruction of the relevant region of interest. 3. The CT arbitrary section ultrasound visual field simulation-assisted ablation path planning method according to claim 2, wherein the step (2) comprises the following sub-steps: (2.1) Calculate the geometric center coordinates of the tumor based on the three-dimensional tumor model; (2.2) Two points p1 and p2 were selected on the right body surface parallel to the intercostal space as the initial position of the probe, and the CT slice was determined in combination with the center point of the tumor. 4. The method for planning an ultrasound field of view simulation-assisted ablation path of any CT slice according to claim 3, wherein: in the step (2.1), the calculation is realized by the following method: calculating the mean value of the coordinates of the data points of the tumor body, or by Double profile loop iteratively find the point of maximum tumor diameter. 5 . The method according to claim 4 , wherein the step (2.2) is realized by a multi-planar reconstruction method. 6 . 6. The CT arbitrary section ultrasound visual field simulation-assisted ablation path planning method according to claim 5, wherein the step (3) comprises the following sub-steps: (3.1) Using the probe model as an input parameter, obtain the ultrasonic transducer array width L in the probe, the conventional imaging angle θ during ultrasound surgery, the depth information H and the CT image resolution p; (3.2) According to the position coordinates of the two points of the initial probe, an initial two-dimensional matrix M1(H, W) is generated on the CT slice, where W=2*H*sin(θ/2)+L*tan(θ/2), The starting point of the left line boundary of the ultrasonic fan is a[1, a], where a=int[H*sin(θ/2)-L(1-tan(θ/2))/2)/p], the left side of the right starting point b[1,b], where b=int[a+L/p], the coordinates of the end point of the left line of the ultrasound line boundary c[c,1], where c=int[(H*cos(θ/2)-L* (1-tan(θ/2))/tan(θ/2)/2)/p], the coordinates of the end point of the ultrasound right boundary d[c, d1], where d1=int[W/p]; (3.3) The radian boundary coordinates of the left side of the deep part of the fan shape are determined by [int[(h+k*radian(θ)/s/2)/p], k], where k=1, 2, 3...w/p/2 , the radian boundary coordinates of the right side are obtained from the symmetry information, and the radians of the shallow sector of the sector are calculated in the same way; (3.4) Replace the pixel value outside the sector boundary of the M1 matrix with 0 to generate a matrix M2, which is an ultrasound field simulation matrix. 7. The CT arbitrary section ultrasound visual field simulation-assisted ablation path planning method according to claim 6, wherein the step (4) comprises the following sub-steps: (4.1) Take the right boundary point of the probe as the needle insertion point and the tumor center as the target point to generate the initial needle insertion path; (4.2) Using the blood vessel V as the constraint condition, determine whether the path intersects with the blood vessel. If it intersects, rotate to the right by a certain angle with the center of the tumor as the center until it does not intersect the blood vessel, and determine the needle entry path N1 in this plane. 8 . The method according to claim 7 , characterized in that the certain angle in the step (4.2) is 5°. 9 . The method according to claim 8 , characterized in that: in the step (5), according to the type of ablation needle, the intersection of the path and the distal boundary of the tumor is taken as the thermal field length The axis boundary point generates a simulated thermal field, and the thermal field parameters are set according to the type of ablation needle. 10. CT arbitrary section ultrasound visual field simulation-assisted ablation path planning system, characterized in that: it includes: Data import module, which is configured to acquire CT images; Reconstruction modules configured to reconstruct bone, body surface, liver, tumor, blood vessel data; A CT section generation module configured to select an ultrasound probe position parallel to the right intercostal space, and to generate a CT section through the center of the tumor, ensuring that the section does not intersect the ribs; A simulated ultrasound field of view module, which is configured to cut and transform the CT section to simulate the actual abdominal ultrasound field of view; A needle entry path generation module, which is configured to generate a needle entry path within the ultrasound field of view plane, and the path needs to satisfy the constraint condition that it does not intersect with the blood vessel; The simulation thermal field generation module is configured to determine the spatial coverage relationship between the thermal field and the tumor. If the thermal field is not completely covered, a parallel section of the plane is obtained along the long axis of the coronal tumor, and the simulated ultrasound field of view module is executed until the thermal field completely covers the tumor. .

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