Steam ablation planning and navigation method and system based on multimodal medical image fusion

Abstract

The present invention provides a steam ablation planning and navigation method and system based on multimodal medical image fusion, the method comprising the following steps: receiving a human MRI medical diagnostic image, segmenting a prostate hyperplasia area; receiving a human ultrasound image, registering the human ultrasound image and the MRI medical diagnostic image to obtain a registration matrix, the registration matrix converting the ultrasound coordinate system to the MRI coordinate system; dividing the prostate hyperplasia area into a plurality of ablation areas; receiving a human ultrasound image acquired in real time, mapping the human ultrasound image acquired in real time to the MRI medical diagnostic image based on the registration matrix; identifying a first ultrasound plane tangent to each ablation area; receiving a projection of an ablation gun on the first ultrasound plane, identifying the ablation position and excitation direction of the ablation gun corresponding to each ablation area, helping a navigation operator to complete the operation of the corresponding ablation area, and effectively improving the accuracy and reliability of the operation.

Description

Technical Field

[0001] The present invention relates to the technical field of medical image processing, and in particular to a steam ablation planning and navigation method and system based on multimodal medical image fusion. Background Art

[0002] Prostatic hyperplasia, also known as benign prostatic hyperplasia, is a common age-related disease in men, usually manifested by symptoms such as frequent urination, urgency, increased nocturia, and dysuria. Prostatic hyperplasia mainly affects the quality of life of middle-aged and elderly men, and its incidence rate gradually increases with age.

[0003] Treatments for prostate hyperplasia include medication, minimally invasive surgery, and traditional surgery. Conservative medication is suitable for patients with mild symptoms, but has little effect on severe patients. Traditional surgery is more traumatic, takes longer to recover, and requires longer hospital stays. It is more risky and may cause complications such as bleeding, infection, and urinary incontinence. Minimally invasive surgery is less invasive, has a faster recovery, and takes a shorter time to operate. The urethra retains the catheter for a shorter time after surgery.

[0004] Steam ablation technology has become a better choice for relieving symptoms while minimizing or eliminating hospitalization time and postoperative complications. How to better plan and guide medical staff during surgery under ultrasound guidance has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to address the planning and navigation issues of steam ablation and to propose a steam ablation planning and navigation method and system based on multimodal medical image fusion.

[0006] The technical solution of the present invention is:

[0007] The present invention provides a steam ablation planning and navigation method based on multimodal medical image fusion, the method comprising the following steps:

[0008] S1, receiving human MRI medical diagnostic images and segmenting the prostate hyperplasia area;

[0009] S2, receiving a human ultrasound image, registering the human ultrasound image and the MRI medical diagnostic image to obtain a registration matrix, which converts the ultrasound coordinate system into the MRI coordinate system;

[0010] S3, dividing the prostate hyperplasia area into several ablation areas;

[0011] S4, receiving a human ultrasound image acquired in real time, and mapping the human ultrasound image acquired in real time to an MRI medical diagnostic image based on the registration matrix acquired in S2;

[0012] A first ultrasonic plane tangent to each ablation region is identified; a projection of the ablation gun on the first ultrasonic plane is received, and the ablation gun steam ablation position and excitation direction corresponding to each ablation region are identified.

[0013] Furthermore, S3 is specifically:

[0014] S31, obtaining the minimum circumscribed cuboid of the prostate hyperplasia region;

[0015] S32, establish a coordinate system, where the x direction is from right to left of the human body, the y direction is from head to toe of the human body, and the z direction is from chest to back of the human body; obtain the physical length zl of the minimum circumscribed cuboid along the z axis and the physical length yl along the y axis;

[0016] S33, comparing the physical length zl of the z-axis with a threshold value 1, and determining whether to divide the minimum circumscribed cuboid along the z-axis;

[0017] If the physical length zl≤threshold 1, the minimum circumscribed cuboid is divided along the y-axis according to the first division method to obtain a plurality of first ablation blocks, and whether each first ablation block is a reserved block is further determined, and the reserved block is used as the ablation area;

[0018] If the physical length zl>threshold 1, the minimum circumscribed cuboid is divided along the y-axis and then along the middle of the z-axis according to the second division method to obtain multiple second ablation blocks, and then it is determined whether each second ablation block is a reserved block, and the reserved block is used as the ablation area.

[0019] Further, in S33, determining whether each first ablation block is a reserved block is specifically as follows:

[0020] Compare whether the volume of each first ablation block is greater than threshold 2, if so, retain the current first ablation block, otherwise, delete the current first ablation block.

[0021] Further, in S33, determining whether each second ablation block is a reserved block is specifically as follows:

[0022] Dividing the plurality of second ablation blocks obtained in the second division manner into two groups along the z-axis;

[0023] Comparing whether the volume of each second ablation block is greater than a threshold value 2, if so, retaining the current second ablation block, otherwise, deleting the current second ablation block;

[0024] The retention status of the second ablation blocks is updated based on the block retention status of the corresponding positions of the two groups of second ablation blocks divided along the z-axis.

[0025] Furthermore, based on the block retention status of the corresponding positions of the two groups of second ablation blocks divided along the z-axis, the retention status of the second ablation blocks is updated specifically as follows:

[0026] If the two ablation blocks at the corresponding positions are both reserved, the two second ablation blocks are reserved as two ablation areas;

[0027] If any one of the two ablation blocks at the corresponding position is retained, the two second ablation blocks are retained and merged into one ablation area;

[0028] If the two ablation blocks at the corresponding positions are not to be retained, the two ablation blocks are merged into one. When the volume of the merged ablation block is greater than threshold 2, the merged ablation block is used as an ablation area. Otherwise, the two ablation blocks are deleted.

[0029] Furthermore, in S33, the minimum circumscribed cuboid is divided along the y-axis as follows:

[0030] The ablation interval distance is set according to the ablation range of one needle of the ablation gun, and is divided along the y-axis, with the number of divisions num = physical length yl / ablation interval distance.

[0031] Furthermore, S4 is specifically:

[0032] S41. Obtaining the center of gravity of any ablation area;

[0033] S42, receiving a human body ultrasound image acquired in real time and mapping it to an MRI medical diagnostic image, identifying a first ultrasound plane tangent to the ablation region, and recording the number of the ablation region tangent to the first ultrasound plane;

[0034] S43, receiving the projection of the ablation gun on the first ultrasonic plane, and when it is recognized that the ablation gun and the first ultrasonic plane are in the same plane, the ablation gun reaches the steam ablation position of the current ablation area;

[0035] S44, receiving the projection of the ablation gun rotating at the steam ablation position, and when the projection of the arrow from the needle seat to the needle tip of the ablation gun on the ultrasound plane points to the outline of the current ablation area, locking it as the excitation direction of the ablation gun;

[0036] S45. Traverse all ablation areas and obtain the steam ablation position and excitation direction of each ablation area according to S41-S44.

[0037] Further, in S42, the first ultrasound plane tangent to the ablation area is identified as:

[0038] Calculate the distance from the real-time acquired human ultrasound image to the center of gravity of the ablation area dis 1;

[0039] ;

[0040] in: ustlis the physical coordinate of the upper left corner of the ultrasound plane, usNorm is the normal vector of the ultrasound plane, is the modulus of the normal vector of the ultrasound plane, p The spatial physical location representing the center of gravity of the ablation area;

[0041] Distance dis 1 compared with threshold 3, when dis 1<threshold 3, the current ultrasound plane is tangent to the corresponding ablation area.

[0042] Further, in S43, identifying that the ablation gun and the first ultrasound plane are in the same plane specifically includes:

[0043] S431, calculating the distance from the ablation gun to the first ultrasound plane dis 2;

[0044] ;

[0045] in: tip is the projection coordinate of the ablation gun tip, ustl is the physical coordinate of the upper left corner of the ultrasound plane, usNorm is the normal vector to the ultrasound plane;

[0046] S432, distance dis 2 is compared with threshold 4;

[0047] when <Threshold 4, the current ablation gun and the first ultrasound plane are in the same plane;

[0048] when dis 2>Threshold 4: The ablation gun has not reached the ultrasound plane along the advancing direction, prompting the operator or medical staff to continue advancing the ablation gun;

[0049] when dis 2<-threshold 4, the ablation gun exceeds the ultrasonic plane in the advancing direction, prompting the operator or medical staff to retract the ablation gun.

[0050] A system used in a steam ablation planning and navigation method based on multimodal medical image fusion, the system comprising:

[0051] Data preparation module: receiving human MRI medical diagnostic images, segmenting the prostate area and prostate hyperplasia area, and performing 3D reconstruction and rendering of the segmented prostate area;

[0052] Data fusion module: receiving human ultrasound images, and performing registration and fusion of human ultrasound images and MRI medical diagnostic images;

[0053] Steam ablation planning module: divides the reconstructed and rendered prostate hyperplasia area into several ablation areas, and performs three-dimensional reconstruction and rendering of the ablation areas;

[0054] Steam ablation navigation module: receiving the real-time acquired human ultrasound image, identifying the first ultrasound plane tangent to each ablation area; receiving the projection of the ablation gun on the first ultrasound plane, identifying the ablation gun steam ablation position and excitation direction corresponding to each ablation area;

[0055] Navigation visualization module:

[0056] The real-time received human ultrasound image, the corresponding MRI medical diagnostic image, the ablation range and excitation direction of the ablation gun and the number of the corresponding ablation area are displayed in real time.

[0057] Beneficial effects of the present invention:

[0058] The steam ablation navigation module of the present invention determines whether the ultrasonic plane is tangent to each area, identifies the first ultrasonic plane tangent to the ablation area, and the ultrasonic probe arrives at the position; receives the projection of the ablation gun on the first ultrasonic plane, and when it is identified that the ablation gun and the first ultrasonic plane are in the same plane, the ablation gun reaches the steam ablation position of the current ablation area; further receives the projection of the operator rotating the ablation gun, and when the projection of the arrow from the ablation gun needle seat to the needle tip on the ultrasonic plane points to the outline of the current ablation area, it is locked as the excitation direction of the ablation gun. At this time, the correct excitation direction is found, prompting the operator to excite the ablation gun, helping the navigation operator to complete the operation of the corresponding ablation area, and cyclically operates this process to complete the ablation steps of all ablation areas, effectively improving the accuracy and reliability of the operation.

[0059] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0061] Figure 1 A flow chart showing the division of a prostate hyperplasia area into several ablation areas according to the present invention.

[0062] Figure 2 A schematic diagram of the present invention with labeled proliferative regions is shown.

[0063] Figure 3 A schematic diagram of the partitioned proliferation area of ​​the present invention is shown.

[0064] Figure 4 A schematic diagram of fusion guidance of the present invention is shown. DETAILED DESCRIPTION

[0065] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0066] Embodiment 1

[0067] A steam ablation planning and navigation method based on multimodal medical image fusion, the method comprising the following steps:

[0068] S1, receiving human MRI medical diagnostic images and segmenting the prostate hyperplasia area;

[0069] S2, receiving a human ultrasound image, registering the human ultrasound image and the MRI medical diagnostic image to obtain a registration matrix, wherein the registration matrix converts the ultrasound coordinate system to the MRI coordinate system, wherein the registration may adopt an ICP iterative registration method;

[0070] S3, dividing the prostate hyperplasia area into several ablation areas;

[0071] S4. Receive the real-time acquired human ultrasound image, map the real-time acquired human ultrasound image to the MRI medical diagnostic image based on the registration matrix acquired in S2, and identify the first ultrasound plane tangent to each ablation area; receive the projection of the ablation gun on the first ultrasound plane, and identify the ablation gun steam ablation position and excitation direction corresponding to each ablation area.

[0072] like Figure 1 As shown in FIG. 1 , it is a flow chart of dividing a prostate hyperplasia area into a plurality of ablation areas according to the present invention, and S3 is specifically:

[0073] S31, obtaining the minimum circumscribed cuboid of the prostate hyperplasia region;

[0074] S32, establish a coordinate system, where the x direction is from right to left of the human body, the y direction is from head to toe of the human body, and the z direction is from chest to back of the human body; obtain the physical length zl of the minimum circumscribed cuboid along the z axis and the physical length yl along the y axis;

[0075] S33, comparing the physical length zl of the z-axis with a threshold value thre1 to determine whether to divide the minimum circumscribed cuboid along the z-axis; generally, 0.75d<threshold value 1<0.95d is selected, where d is the diameter of the ablation range;

[0076] If the physical length zl≤threshold value thre1, the minimum circumscribed cuboid is divided along the y-axis according to the first division method to obtain a plurality of first ablation blocks, and whether each first ablation block is a reserved block is further determined, and the reserved block is used as the ablation area;

[0077] If the physical length zl>threshold thre1, the minimum circumscribed cuboid is divided along the y-axis and then along the middle of the z-axis according to the second division method to obtain multiple second ablation blocks, and then it is determined whether each second ablation block is a reserved block, and the reserved block is used as the ablation area.

[0078] In one example, S33 determines whether each first ablation block is a reserved block specifically as follows:

[0079] Compare whether the volume of each first ablation block is greater than a threshold value thre2, which is generally selected as 0.8×the volume of the actual ablation range. If yes, keep the current first ablation block, otherwise, delete the current first ablation block.

[0080] In one example, S33 determines whether each second ablation block is a reserved block specifically as follows:

[0081] Dividing the plurality of second ablation blocks obtained in the second division manner into two groups along the z-axis;

[0082] Comparing whether the volume of each second ablation block is greater than a threshold value 2, if so, retaining the current second ablation block, otherwise, deleting the current second ablation block;

[0083] The retention status of the second ablation blocks is updated based on the block retention status of the corresponding positions of the two groups of second ablation blocks divided along the z-axis.

[0084] In one example, based on the block retention status of the corresponding positions of the two groups of second ablation blocks divided along the z-axis, updating the retention status of the second ablation blocks is specifically as follows:

[0085] If the two ablation blocks at the corresponding positions are both reserved, the two second ablation blocks are reserved as two ablation areas;

[0086] If any one of the two ablation blocks at the corresponding position is retained, the two second ablation blocks are retained and merged into one ablation area;

[0087] If the two ablation blocks at the corresponding positions are not to be retained, the two ablation blocks are merged into one. When the volume of the merged ablation block is greater than threshold 2, the merged ablation block is used as an ablation area. Otherwise, the two ablation blocks are deleted.

[0088] In one example, S33 divides the minimum circumscribed cuboid along the y-axis as follows:

[0089] The ablation interval distance is set according to the ablation range of one needle of the ablation gun, and is divided along the y-axis, with the number of divisions num = physical length yl / ablation interval distance.

[0090] In one example, S4 is specifically:

[0091] S41. Obtaining the center of gravity of any ablation area;

[0092] S42, receiving a human body ultrasound image acquired in real time, identifying a first ultrasound plane tangent to the ablation region, and recording the number of the ablation region tangent to the first ultrasound plane;

[0093] S43, receiving the projection of the ablation gun on the first ultrasonic plane, and when it is recognized that the ablation gun and the first ultrasonic plane are in the same plane, the ablation gun reaches the steam ablation position of the current ablation area;

[0094] S44, receiving the projection of the ablation gun rotating at the steam ablation position, when the projection of the arrow from the ablation gun needle seat to the needle tip on the ultrasound plane points to the outline of the current ablation area, lock it as the excitation direction of the ablation gun, such as Figure 4 A schematic diagram of fusion guidance of the present invention is shown;

[0095] S45. Traverse all ablation areas and obtain the steam ablation position and excitation direction of each ablation area according to S41-S44.

[0096] In one example, S42 identifies that the first ultrasound plane tangent to the ablation region is specifically:

[0097] Calculate the distance from the real-time acquired human ultrasound image to the center of gravity of the ablation area ;

[0098] ;

[0099] in: is the physical coordinate of the upper left corner of the ultrasound plane, is the normal vector of the ultrasound plane, is the modulus of the normal vector of the ultrasound plane, The spatial physical location representing the center of gravity of the ablation area;

[0100] in: is the physical coordinate of the upper left corner of the ultrasound plane, is the normal vector of the ultrasound plane, is the modulus of the normal vector of the ultrasound plane, The spatial physical location representing the center of gravity of the ablation area;

[0101] Distance Compared with threshold 3, threshold 3 is used to determine whether the current ultrasound plane is tangent to the current ablation area. Generally, 0.05*d<threshold 3<~0.15*d is selected. When the value is less than the threshold value 3, the current ultrasound plane is tangent to the corresponding ablation area.

[0102] In one example, S43 identifies that the ablation gun and the first ultrasound plane are in the same plane as follows:

[0103] S431, calculating the distance from the ablation gun to the first ultrasound plane ;

[0104] ;

[0105] in: is the projection coordinate of the ablation gun tip, is the physical coordinate of the upper left corner of the ultrasound plane, is the normal vector to the ultrasound plane;

[0106] S432, distance Compare with threshold 4, where threshold 4 is used to determine the positional relationship between the current ultrasound plane and the current ablation gun, and is generally selected from 1mm to 1.5mm;

[0107] when <Threshold 4, the current ablation gun and the first ultrasound plane are in the same plane;

[0108] when >Threshold 4: The ablation gun has not reached the ultrasound plane along the advancing direction, prompting the operator or medical staff to continue advancing the ablation gun;

[0109] when <-Threshold 4, the ablation gun exceeds the ultrasonic plane in the advancing direction, prompting the operator or medical staff to retract the ablation gun.

[0110] Embodiment 2

[0111] The present invention provides a system adopted by a steam ablation planning and navigation method based on multimodal medical image fusion, the system comprising:

[0112] Data preparation module: receiving human MRI medical diagnostic images, segmenting the prostate area and prostate hyperplasia area, and performing 3D reconstruction and rendering of the segmented prostate area;

[0113] Data fusion module: receiving human ultrasound images, and performing registration and fusion of human ultrasound images and MRI medical diagnostic images;

[0114] Steam ablation planning module: divides the reconstructed and rendered prostate hyperplasia area into several ablation areas, and performs three-dimensional reconstruction and rendering of the ablation areas;

[0115] Steam ablation navigation module: receiving the real-time acquired human ultrasound image, identifying the first ultrasound plane tangent to each ablation area; receiving the projection of the ablation gun on the first ultrasound plane, identifying the ablation gun steam ablation position and excitation direction corresponding to each ablation area;

[0116] Navigation visualization module: presents the real-time received human ultrasound images and the projection of the ablation gun on the 3D reconstructed and rendered MRI medical diagnostic images.

[0117] During specific operations, the steam ablation navigation module identifies the first ultrasonic plane tangent to the ablation area by judging whether the ultrasonic plane is tangent to each area, that is, when the operator cuts the probe ultrasonic plane to a certain ablation area, the operator is prompted to reach the position of the probe; the operator slowly advances the ablation gun along the urethra, and at this time receives the projection of the ablation gun on the first ultrasonic plane. When it is identified that the ablation gun and the first ultrasonic plane are in the same plane, the ablation gun reaches the steam ablation position of the current ablation area, and the operator is prompted not to advance the ablation gun any further; further, the projection of the operator rotating the ablation gun is received, and when the projection of the arrow from the ablation gun needle seat to the needle tip on the ultrasonic plane points to the outline of the current ablation area, it is locked as the excitation direction of the ablation gun. At this time, the correct excitation direction is found, and the operator is prompted to excite the ablation gun, helping the navigation operator to complete the operation of the corresponding ablation area. This process is cyclically operated to complete the ablation steps of all ablation areas, effectively improving the accuracy and reliability of the operation.

[0118] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A steam ablation planning and navigation system based on multimodal medical image fusion, characterized in that: The system includes: Data preparation module: Receives human MRI medical diagnostic images, segments the prostate area and prostate hyperplasia area, and performs 3D reconstruction and rendering of the segmented prostate area; Data fusion module: receives human ultrasound images and performs registration and fusion on human ultrasound images and MRI medical diagnostic images; Steam ablation planning module: divides the reconstructed and rendered prostate hyperplasia area into several ablation areas, and performs 3D reconstruction and rendering of the ablation areas; Steam ablation navigation module: receives real-time human ultrasound images and identifies the first ultrasound plane tangent to each ablation area; receives the projection of the ablation gun on the first ultrasound plane and identifies the steam ablation position and excitation direction of the ablation gun corresponding to each ablation area; Navigation visualization module: Display the real-time received human ultrasound image, the corresponding MRI medical diagnostic image, the ablation range and excitation direction of the ablation gun, and the number of the corresponding ablation area in real time; The reconstructed and rendered prostate hyperplasia area is divided into several ablation areas, specifically: Obtain the minimum circumscribed cuboid of the prostate hyperplasia area; Establish a coordinate system where the x direction is from right to left of the human body, the y direction is from head to toe of the human body, and the z direction is from chest to back of the human body; obtain the physical length zl of the minimum circumscribed cuboid along the z axis and the physical length yl along the y axis; Compare the physical length zl of the z-axis with the threshold 1 to determine whether to divide the minimum circumscribed cuboid along the z-axis; If the physical length zl ≤ threshold 1, the minimum circumscribed cuboid is divided along the y-axis according to the first division method to obtain multiple first ablation blocks, and whether each first ablation block is a reserved block is further determined, and the reserved block is used as the ablation area; If the physical length zl>threshold 1, the minimum circumscribed cuboid is divided along the y-axis and then along the middle of the z-axis according to the second division method to obtain multiple second ablation blocks, and then it is further determined whether each second ablation block is a retained block, and the retained block is used as the ablation area.

2. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 1 is characterized in that The determination of whether each first ablation block is a reserved block is specifically as follows: Compare the volumes of the first ablation blocks to see whether they are larger than a threshold value 2; if so, retain the current first ablation block; otherwise, delete the current first ablation block.

3. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 1 is characterized in that The determination of whether each second ablation block is a reserved block is specifically as follows: Dividing the plurality of second ablation blocks obtained by the second division method into two groups along the z-axis; Comparing whether the volume of each second ablation block is greater than a threshold value 2, if so, retaining the current second ablation block, otherwise, deleting the current second ablation block; The retention status of the second ablation blocks is updated based on the block retention status of the corresponding positions of the two groups of second ablation blocks divided along the z-axis.

4. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 3 is characterized in that The updating of the retention status of the second ablation block based on the block retention status of the corresponding positions of the two groups of second ablation blocks divided along the z-axis is specifically as follows: If the two ablation blocks at the corresponding positions are both retained, the two second ablation blocks are retained as two ablation areas; If any one of the two ablation blocks at the corresponding position is retained, the two second ablation blocks are retained and merged into one ablation area; If the two ablation blocks at the corresponding positions are not retained, the two ablation blocks are merged into one. When the volume of the merged ablation block is greater than the threshold 2, the merged ablation block is used as an ablation area. Otherwise, the two ablation blocks are deleted.

5. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 1 is characterized in that The division of the minimum circumscribed cuboid along the y-axis is specifically as follows: The ablation interval distance is set according to the ablation range of one needle of the ablation gun, and is divided along the y-axis. The number of divisions num = physical length yl / ablation interval distance.

6. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 1 is characterized in that The steam ablation navigation module is used to perform the following steps: For any ablation area, obtain the center of gravity; receiving a real-time acquired human ultrasound image and mapping it to an MRI medical diagnostic image, identifying a first ultrasound plane tangent to the ablation region, and recording the number of the ablation region tangent to the first ultrasound plane; receiving a projection of the ablation gun on a first ultrasound plane, and when it is recognized that the ablation gun and the first ultrasound plane are in the same plane, the ablation gun reaches a steam ablation position of a current ablation area; receiving a projection of the ablation gun rotating at the steam ablation position, and locking the ablation gun's excitation direction as the arrow from the ablation gun needle base to the needle tip projected on the first ultrasound plane points to the outline of the current ablation area; All ablation areas are traversed to obtain the steam ablation position and excitation direction of each ablation area.

7. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 6 is characterized in that The first ultrasound plane tangent to the ablation area is specifically identified as: Calculate the distance from the real-time human ultrasound image to the center of gravity of the ablation area dis 1; ； in: ustl is the physical coordinate of the upper left corner of the ultrasound plane, usNorm is the normal vector of the ultrasound plane, is the modulus of the normal vector of the ultrasound plane, p The spatial physical location of the center of gravity of the ablation area; The distance dis 1 compared with threshold 3, when dis 1<threshold 3, the current ultrasound plane is tangent to the corresponding ablation area.

8. The steam ablation planning and navigation system based on multimodal medical image fusion according to claim 6 is characterized in that Identifying that the ablation gun and the first ultrasound plane are in the same plane is specifically as follows: Calculate the distance from the ablation gun to the first ultrasound plane dis 2; ； in: tip is the projection coordinate of the ablation gun tip, ustl is the physical coordinate of the upper left corner point of the first ultrasound plane, usNorm is the normal vector of the first ultrasound plane; The distance dis 2 is compared with threshold 4; when dis 2 < threshold 4, the current ablation gun and the first ultrasound plane are in the same plane; when dis 2>Threshold 4: The ablation gun has not reached the ultrasound plane along the advancing direction, prompting the operator to continue advancing the ablation gun; when dis 2<-threshold 4, the ablation gun exceeds the ultrasonic plane in the advancing direction, prompting the operator to retract the ablation gun.

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