A method and system for identifying the deflection degree of a water jet

Abstract

The present application provides a method and system for identifying the deflection degree of a water jet, the method comprising: an image template preset step, pre-acquiring preset water jet images of the water jet on the sagittal plane at multiple deflection angles to form a preset water jet image template set; and / or, pre-acquiring preset jet images corresponding to the jet on the sagittal plane at multiple offset distances to form a preset jet image template set; an image matching step, acquiring an actual water jet image of the water jet and / or an actual jet image of the jet, matching the actual water jet image with the preset water jet image template set, and / or, matching the actual jet image with the image template in the preset jet image template set; when the matching result meets the first condition, determining that the deflection degree of the water jet is acceptable; otherwise, determining that the deflection degree of the water jet is unacceptable. Accordingly, the deflection degree of the water jet can be efficiently and accurately determined and adjusted.

Description

Technical Field

[0001] The present application relates to a method and system capable of efficiently and accurately determining the degree of water jet deflection. Background Art

[0002] During the operation of the water jet, it is necessary to ensure the accurate position of the water jet in the cavity. Specifically, only in the accurate position, that is, when the water jet is not deflected, can the water jet and the water jet image ejected by the water jet be fully displayed on the ultrasound image. This is necessary for water jet surgery. The accurate position can ensure that the operator is provided with complete and accurate information during the operation and the surgery is performed accurately. However, if there is usually an inevitable deflection in the process of arranging the water jet, if the surface where the water jet is actually located is deflected relative to the imaging plane of the ultrasound image, such as the sagittal ultrasound image, the water jet cannot be fully displayed on the sagittal ultrasound image, and then the water jet ejected by the water jet also deviates from the sagittal ultrasound image, resulting in the operator being unable to obtain clear and accurate information about the water jet and the water jet on the ultrasound image, thereby hindering the operation.

[0003] Therefore, when the plane where the water jet is actually located is deflected relative to the imaging plane of the ultrasound image, such as the sagittal ultrasound image, it is necessary to obtain deflection information, such as the direction or angle of the deflection, the distance of the deflection, and other information related to the degree of deflection, and prompt it to the operator or provide it to the control unit of the surgical system so that the position of the water jet can be accurately adjusted before the operation.

[0004] The traditional method repeatedly adjusts the posture of the water jet, including the direction of the water jet head, by controlling the water jet to spray water. This process requires manual observation of the degree of deflection with the help of ultrasound images and judgment based on experience on how to adjust the posture of the water jet to eliminate the deflection until the water jet head reaches the required initial posture. The process is time-consuming and repeated operations can easily cause damage to surrounding tissues, which is undesirable. In addition, there are also problems of low automation and complete reliance on operator experience.

[0005] The degree of deflection of the water jet can also be determined by external devices such as optical or magnetic navigation or identification marks, but additional devices are required for additional marking points or identification sensors. For example, optical navigation must be installed in the external space of the water jet, and there must be no obstruction between the camera and the optical path of the marking point. Magnetic navigation requires the addition of additional sensors on the water jet entering the human cavity and is easily affected by external magnetic fields. Magnetic field receiving sensors need to be added outside the human body, such as on a hospital bed. All of the above will affect the operator's operating space, especially in surgical scenarios where the external operating space is small.

[0006] The degree of deflection of the water jet can also be obtained in real-time ultrasound images, but real-time three-dimensional ultrasound equipment is expensive. Real-time two-dimensional ultrasound images require the operator to repeatedly switch and observe between the sagittal and cross-sectional images, and preset the final trajectory through visual recognition, spatial imagination and experience. There are still technical problems such as the process being time-consuming, relatively low in accuracy, and frequent movement of the ultrasound probe causing damage to the cavity tissue.

[0007] Therefore, in the prior art, there is a technical problem of how to efficiently and accurately identify the degree of water jet deflection without the need for additional devices. Summary of the invention

[0008] In order to achieve the above-mentioned purpose, one scheme of the present application is a method for identifying the degree of deflection of a water knife, wherein the water knife has a knife hole capable of ejecting a jet, and an ultrasonic probe detects and forms a sagittal ultrasound image, comprising the following steps: S1: an image template preset step, wherein the angle between the sagittal plane corresponding to the water knife in the ultrasound image and the plane where the water knife actually lies is taken as the deflection angle, and the distance of the jet relative to the sagittal plane caused by the deflection angle of the plane where the water knife actually lies relative to the sagittal plane corresponding to the ultrasound image is taken as the offset distance; pre-acquire a preset water knife image corresponding to the water knife on the sagittal plane at a plurality of deflection angles to form a preset water knife image template set; and / or pre-acquire a preset jet image corresponding to the jet on the sagittal plane at a plurality of offset distances to form a preset jet image template set, wherein the vertical distance from the center line of the jet to the sagittal plane is taken as the offset distance;

[0009] S2: an image matching step, obtaining an actual water jet image corresponding to the water jet on the sagittal plane, matching the actual water jet image with an image template in the preset water jet image template set, and / or obtaining an actual jet image corresponding to the jet on the sagittal plane, matching the actual jet image with an image template in the preset jet image template set;

[0010] When the matching result meets the preset first condition, it is determined that the deflection degree of the water jet is acceptable and there is no need to adjust the position and posture of the water jet; when the matching result does not meet the preset first condition, it is determined that the deflection degree of the water jet is unacceptable and the position and posture of the water jet needs to be adjusted.

[0011] According to the aforementioned technical solution, image matching is used to preliminarily determine whether the water jet is deflected and whether the degree of deflection is acceptable, so as to improve the accuracy of judgment and adjustment efficiency.

[0012] In a preferred embodiment, a rough deflection angle of the water jet is obtained based on a matching result between the actual water jet image and the preset water jet image template set, and / or a rough offset distance of the jet is obtained based on a matching result between the actual jet image and the preset jet image template set;

[0013] The first condition is that the rough deflection angle is smaller than a preset first deflection angle threshold, and / or the rough offset distance is smaller than a preset first offset distance threshold.

[0014] According to the present invention, when the rough deflection angle and the rough offset distance simultaneously meet the conditions, it is determined that the water jet posture does not need to be adjusted, which can effectively avoid erroneous operation.

[0015] In a preferred embodiment, when the matching result does not satisfy the first condition, the deflection angle calculation step is performed:

[0016] When the matching result satisfies a preset second condition, the deflection angle of the water jet is acquired based on the rough deflection angle and / or the rough offset distance.

[0017] In a preferred embodiment, when the matching result does not satisfy the second condition, an ultrasonic image of at least one cross section perpendicular to the sagittal plane is obtained, and the deflection angle of the water jet is determined based at least on the position of the imaging point of the water jet in the ultrasonic image of the at least one cross section.

[0018] According to the above technical solution, when the rough deflection angle of the water jet and the rough offset distance of the jet are sufficient to accurately determine the deflection angle of the water jet, the deflection angle of the water jet can be calculated only by the sagittal image. When the rough deflection angle of the water jet and the rough offset distance of the jet are insufficient to accurately determine the deflection angle of the water jet, the cross-sectional image is introduced to calculate the deflection angle of the water jet.

[0019] In a preferred embodiment, the second condition is that the rough deflection angle is smaller than a preset second deflection angle threshold, and / or the rough offset distance is smaller than a preset second offset distance threshold; or, the second condition is that the deflection degree of the water jet obtained by weighting the rough deflection angle and the rough offset distance is smaller than a preset deflection degree threshold.

[0020] In a preferred embodiment, in the deflection angle calculation step, a mapping relationship between the preset water jet image template set and the preset jet image template set is pre-established;

[0021] When the matching result satisfies the preset second condition, it is determined whether the actual water jet image and the actual jet image conform to the mapping relationship; if so, it is determined that the rough deflection angle has high credibility, otherwise it is determined that the rough deflection angle has low credibility.

[0022] According to the present invention, when the deflection angle is judged to be highly reliable, the number of water jet adjustments can be reduced, thereby alleviating the burden on the patient. When the deflection angle is judged to be of low reliability, the correct water jet position can be approached step by step to ensure the accuracy of the adjustment.

[0023] In a preferred embodiment, in the deflection angle calculation step, when the matching result does not satisfy the second condition,

[0024] If the matching result satisfies the preset third condition, ultrasonic images of the first cross section and the second cross section set at intervals are obtained, and the water knife is respectively presented as a first imaging point and a second imaging point in the ultrasonic images corresponding to the first cross section and the second cross section; based on the positions of the first imaging point and the second imaging point, the linear equation corresponding to the water knife in the physical space coordinate system is determined;

[0025] If the matching result does not satisfy the third condition, only one cross-sectional ultrasound image is acquired, and the equation of the straight line corresponding to the water knife in the physical space coordinate system is determined based on the position of the imaging point of the water knife in the ultrasound image corresponding to the cross-sectional image and the position of the imaging point of the knife hole in the sagittal ultrasound image;

[0026] The third condition is: the rough deflection angle is greater than a preset third deflection angle threshold, and / or the rough offset distance is greater than a preset third offset distance threshold.

[0027] According to the aforementioned technical solution, when the deflection angle is relatively large, introducing two cross sections can make the angle judgment more accurate.

[0028] In a preferred embodiment, in the deflection angle calculation step, when the matching result does not satisfy the second condition but satisfies the third condition, a cross-sectional image is obtained at a position corresponding to the knife hole in the sagittal ultrasound image as the first cross-sectional image.

[0029] In a preferred embodiment, based on the calibration relationship between the ultrasound image coordinate system and the physical space coordinate system, the first pixel coordinates and the second pixel coordinates of the first imaging point and the second imaging point in the ultrasound image coordinate system are respectively obtained, and then the first pixel coordinates and the second pixel coordinates are converted into the first space coordinates and the second space coordinates in the physical space coordinate system.

[0030] In a preferred embodiment, in the deflection angle calculation step, when the rough deflection angle is greater than / equal to a preset deflection angle threshold, and the rough offset distance is less than / equal to a preset offset distance threshold: only one cross-section is set in the ultrasound image, and based on the position of the imaging point of the water knife on the cross-section and the position of the imaging point of the knife hole on the sagittal plane, the linear equation corresponding to the water knife in the physical space coordinate system is determined.

[0031] According to the aforementioned technical solution, when the deflection angle is relatively small, introducing a cross section can accurately determine the deflection angle while reducing the number and distance of movement of the ultrasonic probe and reducing damage to the cavity tissue.

[0032] In a preferred embodiment, assuming that the safety accuracy is m, and the corresponding maximum deflection angle in the preset water jet image template set is θ0, then in the ultrasound image coordinate system, the distance between the second cross section and the first cross section is m×tanθ0.

[0033] In a preferred embodiment, based at least on the errors in the ultrasonic image acquisition and image recognition process, the calculation accuracy is designed to be n, and the safety factor is p, wherein the safety accuracy m=n×p.

[0034] In addition, another aspect of the present application is a water jet deflection degree identification system, characterized in that: it includes an image acquisition module, an image template matching module and a water jet deflection degree calculation module; the image acquisition module is used to acquire an ultrasonic image of the water jet and its jet; the image template matching module matches the ultrasonic image of the water jet and its jet acquired by the image acquisition module with a preset water jet image template set and a preset jet image template set; the water jet deflection degree calculation module determines the actual deflection degree of the water jet according to the aforementioned water jet deflection degree identification method. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the present application, the following description and drawings of the present application are described and illustrated. Obviously, the drawings in the following description only illustrate certain aspects of some exemplary embodiments of the present application, and it is possible for a person of ordinary skill in the art to obtain other drawings based on these drawings without creative work.

[0036] Figure 1 It is a schematic diagram of the deflection of the water jet.

[0037] Figure 2 is a schematic diagram of a set of preset water jet image templates.

[0038] Figure 3 It is a schematic diagram of a preset jet image template set.

[0039] Figure 4 It is a schematic diagram of the positions of the two transverse planes and the sagittal plane.

[0040] Figure 5 It is a schematic diagram of the imaging of the water jet in two cross sections.

[0041] Figure 6 It is a schematic diagram of the position of the transverse and sagittal planes.

[0042] Caption of the attached figure:

[0043] 1 Sagittal plane

[0044] 10 Preset Waterjet Images

[0045] 11 Preset Jet Images

[0046] 2 Deflection surface

[0047] 20 Waterjet

[0048] 21 Knife hole

[0049] 3 preset water jet image templates collection

[0050] 4 Preset Jet Image Template Collections

[0051] 51 First cross section

[0052] 52 Second Cross Section

[0053] 9 Working Area DETAILED DESCRIPTION

[0054] Various exemplary embodiments of the present application are described in detail below with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is by no means intended to limit the present application and its application or use. The present application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present application thorough and complete and to fully express the scope of the present application to those skilled in the art. It should be noted that unless otherwise stated, the relative arrangement of the components and steps, numerical expressions, and numerical values, etc., described in these embodiments should be interpreted as being merely exemplary, rather than as limitations.

[0055] The words “include” or “comprising” and the like used in this application mean that the elements preceding the words include the elements listed after the words, and do not exclude the possibility of also including other elements.

[0056] All terms (including technical terms or scientific terms) used in this application have the same meaning as those understood by ordinary technicians in the field to which this application belongs, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be understood to have the same meaning as their meanings in the context of the relevant technology, and should not be interpreted in an idealized or extremely formal sense, unless explicitly defined in this article.

[0057] Components not described in detail in this section, parameters such as specific models of components, relationships between components, and control circuits may be considered as technologies, methods, and equipment known to ordinary technicians in the relevant fields, but in appropriate circumstances, such technologies, methods, and equipment should be considered as part of the specification.

[0058] It should be noted that although the operations of the method of the present application are described in a specific order, this does not require or imply that the operations must be performed in the specific order, or that all the operations shown must be performed to achieve the desired results. On the contrary, the steps described in the present application can be performed in a different order. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0059] Waterjet deflection

[0060] The following reference Figure 1 The deflection of the water jet 20 will be described. Figure 1 Schematic diagram of the deflection of the water jet 20.

[0061] Figure 1 The X-axis, Y-axis, and Z-axis shown are physical space coordinate systems. During the operation, the water jet 20 and the ultrasound probe are arranged roughly in a direction parallel to the Y-axis. For example, in a prostate-related surgical scenario, the ultrasound probe is usually inserted into the body cavity through the rectum, and the water jet 20 can be inserted into the tissue through the urethra or perineum. Both contain a slender shaft body, and setting them in parallel directions is conducive to observing the performance of the water jet 20 as a surgical device through the ultrasound probe. In specific operations, the ultrasound probe is usually inserted into the body cavity first. In the subsequent process of arranging the water jet 20, the goal is to arrange the water jet 20 to be aligned with the ultrasound probe. Ideally, it is hoped that this alignment is strictly parallel to the axis of the water jet 20 axis and the ultrasound probe axis. However, inevitably, strict alignment cannot often be achieved in one go when arranging the water jet 20. Figure 1 As shown in , the direction of movement along the Y axis toward the XZ axis plane is the depth direction of the water jet 20. The ultrasonic probe located directly below the water jet 20 is provided with an ultrasonic transducer or a transducer array on its slender shaft body, which is used to detect upward and form a sagittal plane 1 (i.e. Figure 1The water jet 20 is an ultrasonic transducer 20 disposed on the sagittal plane 1, but due to operational errors, the actual position of the arranged water jet 20 may be deflected relative to the sagittal plane 1, and the plane 2 where the water jet 20 is actually located intersects with the sagittal plane 1 and has a certain deflection angle. In this case, the plane 2 where the water jet 20 is actually located is called the deflection plane 2. It can be understood that when the water jet 20 is not deflected, the deflection angle is defined as 0. Among them, the intersection line of the deflection plane 2 and the sagittal plane 1 is parallel to the Z axis and perpendicular to the depth direction of the water jet 20. Since the ultrasonic transducer or transducer array disposed on the slender shaft has a certain width in the direction perpendicular to the Y axis, even if the arranged water jet 20 is deflected, the water jet 20 and / or water jet image can still be observed through the sagittal plane 1 defined by the ultrasonic probe, but due to the deflection, the water jet 20 and / or water jet image observed on the sagittal plane 1 defined by the ultrasonic probe is not an ideal image.

[0062] like Figure 1 As shown, the dotted line segment BD shows the actual position of the water jet 20 on the deflection plane 2, and the solid line segment AC shows the ultrasound image of the water jet 20 on the sagittal plane 1 at this time. When the water jet 20 is deflected, that is, the water jet 20 is actually in a position obliquely passing through the sagittal plane 1, the ultrasound image obtained at this time is the information of the area shown by the solid line segment AC, which is theoretically equivalent to the projection of the standard image of the water jet 20 on the sagittal plane 1, and the length of the solid line segment AC is less than the length of the dotted line segment BD. It can be understood that as the deflection angle gradually increases, the length of the solid line segment AC will gradually decrease, that is, the corresponding imaging of the water jet 20 on the sagittal plane 1 will become shorter and shorter.

[0063] In addition, the water jet 20 has a knife hole 21 ( Figure 1 (not shown in the figure), the dotted circle W in the figure is a schematic diagram of the water jet ejected from the knife hole 21, and the solid circle inside it is a schematic diagram of the ultrasonic image presented by the jet on the sagittal plane 1. In the environment of water jet immersion spraying, due to the cavitation effect, the water jet ejected from the knife hole 21 presents a cone that gradually spreads along the Z axis to the XY plane. When the water jet 20 is deflected, that is, the water jet 20 is actually in a position obliquely passing through the sagittal plane 1, the center line of the jet is located on the deflection plane 2. At this time, the ultrasonic image obtained is the information of the area described by the solid circle, which is theoretically equivalent to the projection of the standard image of the jet on the sagittal plane 1. The vertical distance from the center line of the jet to the sagittal plane 1 is the offset distance. It can be understood that as the deflection angle gradually increases, the offset distance will also gradually increase, and the image of the jet on the sagittal plane 1 will become smaller and smaller, as shown in the figure. The dotted circle W and the solid circle inside it.

[0064] As mentioned above, we found that when the water jet 20 is deflected, the observed water jet image and water jet image will show deviations. In other words, because the water jet 20 is deflected relative to the sagittal plane 1 defined by the ultrasonic probe 1, the water jet 20 and the jet at the knife hole 21 cannot present an ideal standard image on the sagittal plane 1. When the degree of deflection exceeds the ideal threshold, it can be determined that the conditions for operating the water jet 20 for surgery are not met. At this time, it is necessary to help the operator calculate and prompt the deflection angle, and visually display the actual posture of the water jet 20, so that the operator can adjust the posture of the water jet 20 according to the prompt and then perform subsequent surgery; or in an automatically controlled surgical scenario, the deflection angle and other information are fed back to the control unit to control the adjustment of the posture of the water jet 20 to no deflection.

[0065] It should be noted that the deflection, deflection angle, and offset distance mentioned in this application refer to the lateral deflection of the water jet 20 relative to the sagittal plane 1 around an axis parallel to the Z axis, rather than the up and down pitch deflection of the water jet 20 around an axis parallel to the X axis. Those skilled in the art should understand that for the up and down pitch deflection, its deflection information can be directly obtained in the sagittal plane 1 image, that is, by comparing it with the standard image, the up and down pitch deflection angle and / or deflection distance can be directly obtained, which is easy for those skilled in the art to obtain, and this application will not elaborate on it here.

[0066] For the convenience of description, the present application takes the position of the water jet 20 as the deflection point, that is, the water jet 20 deflects laterally around the water jet. In fact, the knife hole 21 or other positions can also be used as the deflection point, and here it is just described by taking the deflection around the knife head as an example. Similarly, the water jet is used as the jet ejected from the knife hole 21, and there is no specific limitation in practice.

[0067] Deflection degree identification

[0068] Next, combine Figure 2-6 A method for identifying the degree of deflection of the water jet 20 will be described in detail. Figure 2 is a schematic diagram of preset water jet image template set 3, Figure 3 is a schematic diagram of a preset jet image template set 4, Figure 4 This is a schematic diagram of the positions of the two transverse sections and the sagittal plane 1. Figure 5 is a schematic diagram of the imaging of the water jet 20 in two cross sections, Figure 6 It is a schematic diagram of the positions of the transverse section and the sagittal plane 1.

[0069] First, the steps for presetting the S1 image template are described.

[0070] Pre-acquire preset water jet images 10 corresponding to the water jet 20 on the sagittal plane 1 at multiple deflection angles to form a preset water jet image template set 3. As an example, a preliminary experiment is conducted before the operation to fix the hardware parameters such as the water pressure of the water jet of the water jet 20 and the position of the knife hole 21, and multiple deflection angles of the deflection surface 2 are preset, such as setting 5 groups of angles of {0 degree, ±5 degrees, ±10 degrees, ±15 degrees, ±20 degrees}. Figure 2 The ultrasonic images at different deflection angles acquired under the same ultrasonic depth and other acquisition parameters are shown. It can be seen from the figure that when the deflection angle is larger, the image of the blade of the water jet 20, i.e., the preset water jet image 10, is shorter. The group of acquired images is indexed and stored according to the deflection angle and the corresponding ultrasonic image as the preset water jet image template set 3.

[0071] In addition, ultrasound images corresponding to the jet on the sagittal plane 1 at multiple offset distances, namely preset jet images 11, are obtained in advance to form a preset jet image template set 4. As an example, before the operation, a preliminary experiment is conducted to fix the hardware parameters such as the water pressure of the water jet of the water knife 20 and the position of the knife hole 21, and multiple offset distances of the deflection surface 2 are preset. In this embodiment, 5 groups of offset distances {0mm, 2mm, 4mm, 8mm, 10mm} are set, such as Figure 3 The water jet images at different offset distances acquired under the same acquisition parameters such as ultrasonic depth are shown, i.e., the preset jet image 11. It can be seen from the figure that when the offset distance is larger, the area of ​​the water jet imaging, i.e., the preset jet image 11, is smaller. The group of acquired images is indexed and stored according to the offset distance and the corresponding ultrasonic image as the preset jet image template set 4.

[0072] Afterwards, the characteristic parameters of the image templates in the preset water jet image template set 3 and the preset jet image template set 4 are obtained through image segmentation algorithm analysis, such as height, width, aspect ratio, perimeter, grayscale value range, etc., and these parameters are used as inputs for template matching to perform the template matching step. In order to facilitate efficient matching calculation and determination of the deflection angle in the subsequent steps, the characteristic parameters are used as part of the index record information, and one or more of the height, width, length, aspect ratio, perimeter, and grayscale value range of the jet profile or the water jet 20 profile in the jet image or water jet image can be selected for indexing and storage. When matching, the parameters stored in the index can be directly calculated. In addition, the preset water jet image template set 3 and the preset water jet image template set 4 based on different ultrasonic acquisition parameters can be set for different ultrasonic acquisition parameters of the ultrasonic probe, such as ultrasonic depth, contrast, etc. Furthermore, by changing the water pressure of the water jet of the water jet 20, image template sets under different water pressures can be generated based on a similar method as described above; template sets under different water jet pressures are particularly suitable for the case where the preset jet image template set 4 is used for subsequent deflection degree judgment. Here, only one set of preset water jet image template sets 3 and one set of preset jet image template sets 4 are used as examples for description, but it should be understood that the subsequent steps are also applicable to the case of multiple sets of preset water jet image template sets 3 or multiple sets of preset jet image template sets 4.

[0073] Next, the S2 image matching step is described.

[0074] As mentioned above, a set of image templates of the water jet 20 under the same ultrasonic depth and other parameters is pre-set, and the characteristic parameters of the template are determined by the image segmentation algorithm, and the corresponding deflection angle / offset distance, image, and characteristic parameters are indexed and stored. As an example, the characteristic parameters of the image templates in the image template set at least include: the position of the knife hole 21 and the length of the water jet 20.

[0075] After the water jet 20 is arranged in the operation area 9, it is necessary to judge the degree of deflection of the water jet 20 according to the acquired ultrasound image, and determine the direction and amplitude of adjustment of the water jet 20 according to the judgment result. Specifically, the actual water jet image corresponding to the water jet 20 on the sagittal plane 1 is obtained, and the actual water jet image is matched with the image template in the preset water jet image template set 3; and / or, the actual jet image corresponding to the jet on the sagittal plane 1 is obtained, and the actual jet image is matched with the image template in the preset jet image template set 4.

[0076] When the matching result satisfies the preset first condition, it is determined that the deflection degree of the water jet 20 is acceptable and there is no need to adjust the position and posture of the water jet 20. At this time, the deflection of the water jet 20 is considered to be slight and does not affect the execution of the operation. The system can prompt the operator that no adjustment is required, or only fine-tune the deflection angle and / or deflection distance. When the matching result does not meet the preset first condition, it is determined that the deflection degree of the water jet 20 is unacceptable and the position and posture of the water jet 20 needs to be adjusted.

[0077] Specifically, after obtaining the actual water jet image corresponding to the water jet 20 on the sagittal plane 1, the length AC of the water jet 20 and the position of the knife hole 21 corresponding to the jet W of the water jet water jet in the image are obtained according to the image segmentation algorithm, and the water jet 20 length and knife hole 21 position information in the actual water jet image are obtained to find the index, determine the image template in the image template set, and the corresponding deflection angle / offset distance, and overlay the determined image template in the image template set on the actual sagittal plane image, so that the operator can intuitively see the deflection degree of the water jet 20. Optionally, the deflection angle / offset distance information can also be displayed on the display device at the same time, or sent to the control unit for water jet 20 posture adjustment. In this way, after the water jet 20 is arranged at the predetermined position, the deflection degree information can be quickly determined based on the sagittal plane ultrasound image acquired in real time, and an image reflecting the deflection degree of the water jet 20 can be quickly called from the template set stored in the storage device, and superimposed and displayed on the actual sagittal plane 1 image with different effects (such as translucent, or different colors, etc.), which can provide guidance to the operator at the first time, greatly improving the efficiency and accuracy of the operator in arranging the water jet 20.

[0078] Furthermore, a rough deflection angle of the water jet 20 is obtained based on the matching result between the actual water jet image and the preset water jet image template set 3, and / or a rough offset distance of the jet is obtained based on the matching result between the actual jet image and the preset jet image template set 4; the first condition is that the rough deflection angle is smaller than a preset first deflection angle threshold, and / or the rough offset distance is smaller than a preset first offset distance threshold.

[0079] Specifically, the deflection angle of the water jet 20 and the offset distance of the jet are essentially different representations of the same phenomenon. That is, when the water jet 20 deflects relative to the sagittal plane 1, the jet will inevitably be offset relative to the sagittal plane 1. When the deflection plane 2 is at a certain deflection angle, the jet will also be at an offset distance corresponding to it. In other words, the deflection angle of the water jet 20 and the offset distance of the jet are two phenomena caused by the same fact, and there is a mapping relationship between the two. However, due to the influence of image quality and noise, the deflection angle of the water jet 20 and the offset distance of the jet may not conform to the mapping relationship as expected. For example, the deflection angle indicated by the preset water jet image template that matches the actual water jet image is 5°, while the offset distance indicated by the preset jet image template that matches the actual jet image is not the offset distance corresponding to the deflection angle of 5°.

[0080] This is because at least one of the deflection angle of the water jet 20 and the offset distance of the jet has errors due to the influence of image quality and noise. Therefore, it is possible to use the two dimensions of the deflection angle of the water jet 20 or the offset distance of the jet. However, for a more complex imaging environment, it is more preferred to determine the deflection degree of the water jet based on both the deflection angle of the water jet 20 and the offset distance of the jet, which can better avoid misjudgment. In particular, after the conclusion that the deflection degree is negligible and there is no need to adjust the posture of the water jet 20 is drawn based on one of the dimensions, in order to ensure the reliability of the conclusion, another dimension is introduced to determine the deflection degree. For example, when the rough deflection angle of the water jet 20 is obtained based on the matching result of the actual water jet image and the preset water jet image template set 3, and it is determined that the rough deflection angle is less than the preset first deflection angle threshold, the system can prompt that the deflection degree of the water jet 20 is acceptable; or, the system introduces the judgment of the offset distance, that is, based on the matching result of the actual jet image and the preset jet image template set 4, the rough offset distance of the jet is obtained, and it is judged whether the rough offset distance is less than the preset first offset distance threshold. When the rough offset distance is less than the preset first offset distance threshold, the system directly gives a conclusion that no adjustment is required. When the rough offset distance is greater than the preset first offset distance threshold, the system will prompt for fine-tuning. It should be understood that the above steps can be reversed, that is, the rough offset distance is judged first, and then the rough offset angle is judged. And, as mentioned above, the preferred solution is that only when the rough deflection angle is smaller than the preset first deflection angle threshold and the rough offset distance is smaller than the preset first offset distance threshold, the deflection degree of the water jet 20 is considered to be small and there is no need to adjust the posture of the water jet 20.

[0081] Further, when the matching result does not meet the preset first condition, the deflection angle calculation step S3 is entered. In the deflection angle calculation step, it is determined whether the matching result meets the preset second condition. The second condition is that the rough deflection angle is less than the preset second deflection angle threshold, and / or the rough offset distance is less than the preset second offset distance threshold.

[0082] Here, the second deflection angle threshold is greater than the aforementioned first deflection angle threshold, and the second offset distance threshold is greater than the aforementioned first offset distance threshold.

[0083] In addition, the second condition may also be that the deflection degree of the water jet obtained by weighting the rough deflection angle and the rough offset distance is less than a preset deflection degree threshold.

[0084] When the matching result satisfies the preset second condition, that is, although the water jet 20 needs to adjust its posture, its deflection degree is still relatively small, the deflection angle of the water jet can be directly calculated based on the rough deflection angle and / or the rough offset distance. This is because, when the water jet 20 is deflected relative to the sagittal plane 1, the water jet 20 passes through the sagittal plane 1 at an angle. The larger the deflection angle, the smaller the projection of the water jet 20 on the sagittal plane 1, and the farther the jet is from the sagittal plane 1. Therefore, the accuracy of the rough deflection angle determined based on the image of the water jet 20 on the sagittal plane 1 and the rough offset distance determined based on the image of the jet on the sagittal plane 1 is lower. On the contrary, the smaller the deflection angle, the higher the accuracy of the rough deflection angle determined based on the image of the water jet 20 on the sagittal plane 1 and the rough offset distance determined based on the image of the jet on the sagittal plane 1.

[0085] Therefore, when it is determined that the position of the water jet 20 needs to be adjusted, the second condition is used to determine whether the deflection angle of the water jet 20 is small, so that the rough deflection angle of the water jet 20 and the rough offset distance of the jet are sufficient to accurately calculate the deflection angle of the water jet 20.

[0086] When the matching result does not meet the preset second condition, the deflection angle of the water jet 20 is relatively large. At this time, the rough deflection angle of the water jet 20 and the rough offset distance of the jet are not enough to accurately determine the deflection angle of the water jet 20. In this case, it is necessary to introduce a cross-sectional image for more accurate angle calculation, and determine the deflection angle of the water jet 20 through at least one cross-section perpendicular to the sagittal plane 1. The cross-section of the present application is perpendicular to the depth direction of the ultrasound probe, that is, the Y-axis direction.

[0087] It should be noted that the acquisition of the cross-sectional image requires the movement of the ultrasonic probe, which will bring a certain burden to the patient. According to the present invention, when the rough deflection angle of the water jet 20 and the rough offset distance of the jet are sufficient to accurately determine the deflection angle of the water jet 20, the deflection angle of the water jet 20 is calculated based on the sagittal image. Only when the deflection angle of the water jet 20 is large, the deflection angle of the water jet 20 is calculated based on the cross-sectional image, thereby minimizing the burden on the patient.

[0088] In addition, the deflection angle of the water jet 20 calculated through the above steps usually needs to be prompted to the operator by means of visual display, so as to help the operator quickly complete the posture adjustment of the water jet 20 according to the prompted deflection angle (corresponding to the angle to be adjusted). The deflection angle of the water jet 20 calculated through the cross-sectional image is usually more accurate (the specific situation will be described later), while the accuracy of the deflection angle of the water jet 20 calculated through the sagittal image depends on the size of the deflection angle.

[0089] Specifically, the smaller the deflection angle of the water jet 20, the higher the accuracy of the rough deflection angle determined based on the image of the water jet 20 on the sagittal plane 1 and the rough offset distance determined based on the image of the jet on the sagittal plane 1. Moreover, as mentioned above, the deflection angle of the water jet 20 and the offset distance of the jet are two phenomena caused by the same fact, and there is a mapping relationship between the two. The smaller the deflection angle of the water jet 20, the higher the accuracy of the rough deflection angle and the rough offset distance, the higher the possibility that the two meet the mapping relationship, and the higher the credibility of the deflection angle of the water jet 20 calculated by these two dimensions.

[0090] On the contrary, when the rough deflection angle of the water knife 20 and the rough offset distance of the jet meet the mapping relationship, it means that the credibility of the deflection angle determined at this time is high. In the process of adjusting the posture of the water knife 20, it is hoped to move the ultrasonic probe and the water knife 20 as little as possible to reduce the burden on the patient. Therefore, when the rough deflection angle of the water knife 20 and the rough offset distance of the jet meet the mapping relationship, the deflection angle determined at this time is relatively accurate, which can be helpful to prompt the operator to adjust the water knife 20 to the desired state through a one-time operation. On the other hand, when the rough deflection angle of the water knife 20 and the rough offset distance of the jet do not meet the mapping relationship, at least one of the two may have a large error, and the operator can be prompted to tentatively adjust the water knife 20, and then judge the deflection degree and determine the deflection angle again, until the rough deflection angle of the water knife 20 and the rough offset distance of the jet meet the mapping relationship, and then adjust the water knife 20 once again. In this way, the burden on the patient can be minimized while ensuring the accuracy of the adjustment.

[0091] Next, the method steps for introducing cross-sectional image information to determine the deflection angle will be described.

[0092] In the deflection angle calculation step, when the matching result does not satisfy the aforementioned second condition, if the matching result satisfies the preset third condition, two cross-sectional ultrasound images set at intervals are obtained, and based on the positions of the imaging points of the water knife 20 in the two cross-sectional images, the corresponding straight line equation of the water knife 20 in the physical space coordinate system is determined; if the matching result does not satisfy the third condition, only one cross-sectional ultrasound image needs to be obtained, and based on the positions of the imaging points of the water knife 20 in the cross-sectional image and the positions of the imaging points of the knife hole 21 in the sagittal plane image, the corresponding straight line equation of the water knife 20 in the physical space coordinate system is determined.

[0093] The third condition is that the rough deflection angle is greater than a preset third deflection angle threshold, and / or the rough offset distance is greater than a preset third offset distance threshold. The third deflection angle threshold is greater than the aforementioned second deflection angle threshold, and the third offset distance threshold is greater than the aforementioned second offset distance threshold.

[0094] Specifically, in the deflection angle calculation step S3, when the matching result does not satisfy the second condition but satisfies the third condition, it means that the deflection angle of the water jet 20 is relatively large, and two cross-sectional images need to be introduced for judgment.

[0095] See also Figure 4 , Figure 5 , obtain the ultrasonic images of the first cross section 51 and the second cross section 52 set at intervals, and the cross-sectional ultrasonic images corresponding to the water jet 20 in the first cross section 51 and the second cross section 52 are presented as the first imaging point B1 and the second imaging point B2 respectively. Since the cross section is roughly perpendicular to the blade of the water jet 20, the image of the water jet 20 on the ultrasonic cross section roughly presents the cross-sectional information of the axis of the water jet 20, which is more often quasi-circular. For the convenience of description, it is expressed as an "imaging point". It should be understood that the "imaging point" can be the fitting center of the contour of the quasi-circular water jet 20. Based on the positions of the first imaging point B1 and the second imaging point B2, determine the linear equation corresponding to the water jet 20 in the physical space coordinate system.

[0096] Next, the actual position of the water jet 20 in the physical space coordinate system can be determined along the straight line direction determined by the straight line equation and the jet position of the water jet 20. Then, the corresponding image template in the image template set can be selected and superimposed in the sagittal image, so that the operator can intuitively see the deflection degree of the water jet 20 and obtain relevant information for subsequent adjustments.

[0097] As an example, the position corresponding to the knife hole 21 in the sagittal plane 1 image is selected to obtain a cross-sectional image as the image of the first cross-sectional 51, that is, the imaging position of the knife hole 21 in the sagittal plane 1 image is taken as the position of the first cross-sectional 51. As described in the scheme of the follow-up display of the sagittal plane 1 image and the cross-sectional image proposed by the inventor of the present application in the previous invention, after the ultrasonic probe is arranged in place, the operator can realize the follow-up display of the sagittal plane 1 image and the cross-sectional image, so the determination of the position is easy to obtain. After determining the acquisition position of the first cross-sectional image, the ultrasonic probe is driven to translate or the image stored in the storage device adjacent to the cross-sectional position is fitted to obtain the cross-sectional image of the cross-sectional position.

[0098] Furthermore, based on the position of the first cross-section 51, a suitable position of the second cross-section 52 is selected, and a second cross-sectional image of the position of the second cross-sectional image 52 is obtained. The method for obtaining the second cross-sectional image is similar to the method for obtaining the first cross-sectional image, and will not be repeated here.

[0099] Among them, the relevant calculation accuracy and safety factor can be pre-set, such as the calculation accuracy is 5mm, the safety factor is 6 times, then the safety accuracy m=5mm×6=30mm, then the distance interval between the first cross section 51 and the second cross section 52 in the Y-axis direction is set to 30mm. The setting of the safety factor here should not be too small or too large. On the one hand, considering the errors of image recognition and ultrasonic images, the first cross section 51 and the second cross section 52 are too close, which will affect the accuracy of the deflection angle judgment, and the safety factor should not be too small; on the other hand, considering that in some scenarios, the ultrasonic probe needs to be driven to move to obtain the cross-sectional image of the position of the second cross section 52, the movement amplitude is not expected to be too large to avoid accidents or injuries, and the safety factor should not be too large; therefore, the distance between the first cross section 51 and the second cross section 52 is determined based on the errors of image recognition and ultrasonic images, and the threshold of the movement amplitude that is desired to be controlled.

[0100] In some embodiments, the coordinates of the positions of the first cross section 51 and the second cross section 52 on the Y axis are y1 and y2 respectively. According to the maximum deflection angle corresponding to the image template in the preset water jet image template set 3, such as 20 degrees, y2=y1+m×tan20. A calibration relationship between the ultrasound image coordinate system and the physical space coordinate system is established in advance, y1 and y2 are converted from the ultrasound image coordinate system to the coordinates of the physical space coordinate system, and then the ultrasound probe is moved to the positions corresponding to y1 and y2 respectively to obtain Figure 5 Cross-sectional images of the positions of the first cross-sectional plane 51 and the second cross-sectional plane 52 are shown.

[0101] As a preferred method, the first pixel coordinates and the second pixel coordinates of the first imaging point B1 and the second imaging point B2 in the ultrasonic image coordinate system are respectively obtained through an image segmentation algorithm, and then the first pixel coordinates and the second pixel coordinates are converted into the first space coordinates and the second space coordinates in the physical space coordinate system according to the calibration relationship. The equation of the straight line where the water jet 20 is located can be determined according to the first space coordinates and the second space coordinates.

[0102] See also Figure 6 When the matching result does not satisfy the second and third conditions mentioned above, it means that although the credibility of the determined deflection angle of the water jet 20 is low, its deflection degree is still relatively small. In this case, in order to improve the calculation efficiency and reduce the movement of the probe, only one cross section can be introduced to determine the deflection angle.

[0103] The specific method is similar to the aforementioned principle of obtaining the images of the first cross-section 51 and the second cross-section 52 and determining the coordinates of the first imaging point B1 and the second imaging point B2, and then determining the linear equation of the water jet 20. The difference is that at this time, the first imaging point B1 is replaced by the imaging point corresponding to the knife hole 21 in the sagittal plane image, that is, there is no need to obtain the cross-sectional image corresponding to the position of the first cross-section 51, and only the cross-sectional image corresponding to the position of the second cross-section 52 needs to be obtained to determine the second imaging point B2, which makes the calculation process more efficient and can also reduce the number of times the ultrasonic probe is moved, that is, it is only necessary to move the ultrasonic probe to the position corresponding to the second cross-section 52, and there is no need to move it to the position corresponding to the first cross-section 51, which not only improves efficiency but also further reduces damage to the cavity tissue.

[0104] Furthermore, the pixel coordinates of the second imaging point B2 and the imaging point of the knife hole 21 in the sagittal plane image are obtained through the image segmentation algorithm, and then the pixel coordinates are converted into physical space coordinates according to the calibration relationship between the ultrasound image coordinate system (which can be the cross-sectional image coordinate system and the sagittal image coordinate system) and the physical space coordinate system, so that the equation of the line where the water knife 20 is located in the physical space coordinate system can be determined. Based on the determined straight line direction and the knife hole position of the water knife 20, the actual position of the water knife 20 in the physical space coordinate system can be determined. Then, the corresponding image template in the image template set can be selected and superimposed on the sagittal plane image, so that the operator can intuitively see the degree of deflection of the water knife 20 and obtain relevant information for subsequent adjustments.

[0105] In summary, the method for identifying the degree of deflection of a water jet of the present application first matches the ultrasonic image of the water jet 20 and / or the jet on the sagittal plane 1 with the pre-established image template to preliminarily determine the deflection angle of the deflection plane 2 relative to the sagittal plane 1 and / or the offset distance of the jet relative to the sagittal plane 1. If the first condition is met, the degree of deflection is considered acceptable. Otherwise, it is determined whether the second condition is met.

[0106] When the first condition is not met, if the second condition is met, it is considered that although the water jet 20 needs to adjust its posture, its deflection degree is still relatively small, and the deflection angle of the water jet can be directly calculated based on the rough deflection angle and / or the rough offset distance; if the second condition is not met, it is determined whether the third condition is met.

[0107] When the second condition is not met, if the third condition is met, the degree of deflection is already quite serious, and it is necessary to introduce information from the cross-sectional images at two cross-sectional positions to increase the accuracy of the deflection angle calculation; if the third condition is not met, only one cross-sectional image needs to be introduced for judgment, which reduces the number and distance of movement of the ultrasound probe, thereby reducing damage to the cavity tissue.

[0108] The water jet deflection degree identification method of the present application can not only determine the water jet deflection degree information efficiently and accurately, but also introduces different judgment strategies according to different deflection degrees, further taking into account efficiency and accuracy. By superimposing the information of the ultrasonic sagittal image and the cross-sectional image, the determination of the deflection angle of the water jet 20 has a higher credibility. At the same time, the water jet 20 and its deflection information are visualized, which facilitates the operator to adjust the posture of the water jet 20 efficiently and accurately.

[0109] At the same time, when the deflection degree of the water jet 20 is acceptable, it is not necessary to introduce the image of the cross-sectional position, that is, it is not necessary to move the ultrasonic probe. When the deflection degree of the water jet 20 is unacceptable, if the deflection angle is relatively small, it is only necessary to introduce an image of the cross-sectional position, that is, the ultrasonic probe is moved once along the Y axis. Only when it is judged that the deflection angle is really large, it is necessary to introduce two images of the cross-sectional position, that is, the ultrasonic probe is moved twice along the Y axis. Therefore, this method also takes into account the accuracy of the deflection angle judgment and reduces the impact on the patient's body tissue, avoiding possible damage.

[0110] It should be noted that only the actual water jet image can be matched with the preset water jet image template set 3 to obtain a rough deflection angle, or the actual jet image can be matched with the preset jet image template to obtain a rough offset distance, and then the first condition, the second condition, and the third condition can be judged according to the rough deflection angle or the rough offset distance. As mentioned above, the deflection angle and the offset distance are different representations of the same phenomenon, and there is a certain corresponding relationship between the two. Acquiring the rough deflection angle and the rough offset distance at the same time and judging the above three conditions is only a preferred implementation of the present application.

[0111] In addition, it should be understood that the storage device involved in the above embodiments may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM) or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0112] And the above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, motor drive or data center to another website, computer, motor drive or data center by infrared, wireless, microwave or the like. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a motor drive, data center, etc. that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0113] Therefore, it can be understood that the present application also provides a water jet deflection degree identification system. The system includes an image acquisition module, an image template matching module and a water jet deflection degree calculation module; the image acquisition module is used to acquire ultrasonic images of the water jet 20 and its jet; the image template matching module matches the ultrasonic images of the water jet 20 and its jet acquired by the image acquisition module with the image templates in the preset water jet image template set 3 and the preset jet image template set 4; the water jet deflection degree calculation module determines the deflection degree of the water jet 20 according to the aforementioned water jet deflection degree identification method. And, the water jet 20 deflection degree identification system provided in the present application is suitable for executing the aforementioned various method steps, and all systems that implement the aforementioned method steps provided in the present application are within the protection scope of the present application.

[0114] It should be understood that the specific embodiments described above are only used to explain the present application, and the protection scope of the present application is not limited thereto. Any technical personnel familiar with the technical field can make changes, substitutions, and combinations within the technical scope disclosed in the present application according to the technical solution and inventive concept of the present application, which should be covered by the protection scope of the present application.

Claims

1. A method for identifying the degree of deflection of a water jet, wherein the water jet has a knife hole capable of ejecting a jet, and an ultrasonic probe detects and forms a sagittal ultrasonic image, characterized in that: The following steps are included: S1: image template preset step, taking the angle between the sagittal plane corresponding to the ultrasound image and the plane where the water jet actually is located as the deflection angle, taking the distance of the jet relative to the sagittal plane caused by the deflection angle of the plane where the water jet actually is located relative to the sagittal plane corresponding to the ultrasound image as the offset distance; pre-acquiring preset water jet images corresponding to the water jet on the sagittal plane at multiple deflection angles to form a preset water jet image template set; and / or pre-acquiring preset jet images corresponding to the jet on the sagittal plane at multiple offset distances to form a preset jet image template set, wherein the vertical distance from the center line of the jet to the sagittal plane is the offset distance; S2: an image matching step, obtaining an actual water jet image corresponding to the water jet on the sagittal plane, and matching the actual water jet image with an image template in the preset water jet image template set; and / or obtaining an actual jet image corresponding to the jet on the sagittal plane, and matching the actual jet image with an image template in the preset jet image template set; When the matching result meets the preset first condition, it is determined that the deflection degree of the water jet is acceptable and there is no need to adjust the position and posture of the water jet; when the matching result does not meet the preset first condition, it is determined that the deflection degree of the water jet is unacceptable and the position and posture of the water jet needs to be adjusted.

2. The method for identifying the degree of deflection of a water jet according to claim 1, characterized in that: Obtaining a rough deflection angle of the water jet based on a matching result between the actual water jet image and the preset water jet image template set, and / or obtaining a rough offset distance of the jet based on a matching result between the actual jet image and the preset jet image template set; The first condition is that the rough deflection angle is smaller than a preset first deflection angle threshold, and / or the rough offset distance is smaller than a preset first offset distance threshold.

3. The method for identifying the degree of deflection of a water jet according to claim 2, characterized in that: When the matching result does not meet the first condition, the deflection angle calculation step is entered: When the matching result satisfies a preset second condition, the deflection angle of the water jet is acquired based on the rough deflection angle and / or the rough offset distance.

4. The method for identifying the degree of deflection of a water jet according to claim 3, characterized in that: When the matching result does not satisfy the second condition, an ultrasonic image of at least one cross section perpendicular to the sagittal plane is acquired, and the deflection angle of the water jet is determined based at least on the position of the imaging point of the water jet in the ultrasonic image of the at least one cross section.

5. The method for identifying the degree of deflection of a water jet according to claim 3, characterized in that: The second condition is that the rough deflection angle is smaller than a preset second deflection angle threshold, and / or the rough offset distance is smaller than a preset second offset distance threshold; or, The second condition is that the deflection degree of the water jet obtained by weighting the rough deflection angle and the rough offset distance is less than a preset deflection degree threshold.

6. The method for identifying the degree of deflection of a water jet according to claim 3, characterized in that: In the deflection angle calculation step, a mapping relationship between the preset water jet image template set and the preset jet image template set is pre-established; When the matching result satisfies the second condition, it is determined whether the actual water jet image and the actual jet image conform to the mapping relationship; if so, the rough deflection angle is determined to have high credibility; otherwise, the rough deflection angle is determined to have low credibility.

7. The method for identifying the degree of deflection of a water jet according to any one of claims 3 to 6, characterized in that: In the deflection angle calculation step, if the matching result does not satisfy the second condition, If the matching result satisfies the preset third condition, ultrasonic images of the first cross section and the second cross section set at intervals are obtained, and the water knife is respectively presented as a first imaging point and a second imaging point in the ultrasonic images corresponding to the first cross section and the second cross section; based on the positions of the first imaging point and the second imaging point, the linear equation corresponding to the water knife in the physical space coordinate system is determined; If the matching result does not satisfy the third condition, only one cross-sectional ultrasound image is acquired, and the equation of the straight line corresponding to the water knife in the physical space coordinate system is determined based on the position of the imaging point of the water knife in the ultrasound image corresponding to the cross-sectional image and the position of the imaging point of the knife hole in the sagittal ultrasound image; The third condition is: the rough deflection angle is greater than a preset third deflection angle threshold, and / or the rough offset distance is greater than a preset third offset distance threshold.

8. The method for identifying the degree of deflection of a water jet according to claim 7, characterized in that: In the deflection angle calculation step, when the matching result does not satisfy the second condition but satisfies the third condition, a position corresponding to the knife hole in the sagittal ultrasound image is selected to obtain a cross-sectional ultrasound image as the first cross-sectional image.

9. The method for identifying the degree of deflection of a water jet according to claim 7, characterized in that: Based on the calibration relationship between the ultrasound image coordinate system and the physical space coordinate system, the first pixel coordinates and the second pixel coordinates of the first imaging point and the second imaging point in the ultrasound image coordinate system are respectively obtained, and then the first pixel coordinates and the second pixel coordinates are converted into the first space coordinates and the second space coordinates in the physical space coordinate system.

10. The method for identifying the degree of deflection of a water jet according to claim 7, characterized in that: Assuming that the safety accuracy is m, and the corresponding maximum deflection angle in the preset water jet image template set is θ0, then in the ultrasound image coordinate system, the distance between the second cross section and the first cross section is m×tanθ0.

11. The method for identifying the degree of deflection of a water jet according to claim 10, characterized in that: At least based on the errors in the ultrasonic image acquisition and image recognition process, the design calculation accuracy is n and the safety factor is p, and the safety accuracy m=n×p.

12. A water jet deflection degree recognition system, characterized in that: It includes an image acquisition module, an image template matching module and a water jet deflection degree calculation module; The image acquisition module is used to acquire ultrasonic images of the water jet and its jet; The image template matching module matches the ultrasonic image of the water jet and its jet acquired by the image acquisition module with a preset water jet image template set and a preset jet image template set; The water jet deflection degree calculation module is suitable for executing the method according to any one of claims 1-11.

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