KR101692442B1 - Method and apparatus for automated pedicle screw placement planning for safe spinal fusion surgery - Google Patents

Abstract

The present invention discloses an automated optimal screw insertion path planning method for spinal surgery. (B) generating a patient mapping bone model by mapping the extracted vertebra bone model to an average bone model; (c) comparing the extracted patient bone model with a mean bone model, Extracting a spinal canal region of the patient from the mapping bone model; and (d) defining a pedicle region from the spinal canal region of the patient to calculate a screw insertion path corresponding to the patient .

Description

[0001] METHOD AND APPARATUS FOR AUTOMATED PEDICLE SCREW PLACEMENT PLANNING FOR SAFE SPINAL FUSION SURGERY [0002]

The present invention relates to an optimal screw insertion path planning method and apparatus, and more particularly, to a method and apparatus for optimizing screw insertion path planning, And to a method and apparatus that are applicable to the most complex and small cervical surgery.

Spinal fusion surgery is a method of relieving pain by fixing screws using a metal rod and screw insertion on two or more vertebrae when the patient complains of pain due to abnormal spinal motion. It is effective for the treatment of various spinal diseases such as lumbar disc herniation, vertebral fracture, lumbar spinal stenosis and spinal dystrophy.

The problem with this procedure is that it is known clinically that about 10% of false screw insertion occurs and about 5% of the patients, half of them, are seriously damaged by wrong insertion. In order to solve these problems, various systems such as a navigation device for confirming the exact screw position or a robot for precise screw insertion have been developed. However, various causes of error during operation (physician effect, medical image distortion, registration ) Errors are still present at a maximum of 1.5 mm (D. Togawa, MM Kayanja, MK Reinhardt, M. Shoham, A. Balter, A. Friedlander, N. Knoller, EC Benzel, and IH Lieberman, Bone-mounted miniature robotic guidance for pedicle screw and translaminar facet screw placement: part 2 - Evaluation of system accuracy, Neurosurgery, vol 60, pp. 129-139, 2007). In addition, not only the spinal cord and the vertebral artery pass through the cervical vertebrae but also the second cervical vertebra C2, compared with the screw size (3.5-4.0 mm in diameter) The width of the pedicle, which is the area where the screw is inserted, is 5.45mm on average, which is dangerous and difficult to insert.

Therefore, for safe operation, these factors can be solved by planning the screw insertion route in the preoperative stage. In order to solve this problem, existing patents have been proposed such as registration number (1010838890000) (hereinafter referred to as prior patent 1) and registration number (10-1264198) (hereinafter referred to as prior patent 2). In the case of the prior patent 1, not only the consideration of screw insertion but also the optimization considering the various outcome factors of the insertion was not taken into consideration, and the safety factor required particularly at the time of operation was not considered. At some stage, a series of user intervention is required. In the case of the prior patent 2, the screwing plan is limited to the lumbar vertebrae, and since the algorithm is developed and is difficult to apply to the cervical vertebrae and is planned considering the parallel path on the CT image, , It may be difficult to calculate an optimal path.

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned problems and to provide a method of removing a risk of screw insertion caused by an insertion error by setting a safety margin in a planning stage before fusion surgery, Thereby providing a method of calculating the thread insertion path so as to prevent damage.

It is another object of the present invention to provide a method and an apparatus for performing an optimal three-dimensional operation, which is safe in different bone shapes among patients and has strong bonding force between screws and bones, Length, path, insertion position, etc.) to the user who is the user.

In order to accomplish the above object, the present invention provides an automated optimal screw insertion route planning method for safe spinal surgery, comprising the steps of: (a) extracting a vertebral bone model of a patient from a medical image; (b) (C) extracting a spinal canal region of the patient from the generated patient-mapped bone model; and (d) extracting a spinal canal region from the spinal canal region of the patient, Defining a pedicle region, and calculating a screw insertion path corresponding to the patient.

The screw insertion path planning method may further include performing (e) adjusting a size of a screw and a safety margin, and repeating the step (d).

By setting the parameter of the PS (Performance Score) allocated to the candidate paths by the input from the user, the shape of the path can be adjusted.

(C) performing initialization for approximate matching between the average bone model and the vertebral bone model of the patient, and (c-2) performing registration for extracting the spinal canal of the patient and performing registration.

The step (c-1) may include performing initialization by calculating a minimum distance value through eigenvector rotation between models using the magnitude order of the eigenvalues of the covariance of the spinal bone model of the patient .

The step (c-2) may be performed by performing rigid registration and non-rigid registration to perform a close operation of the corresponding bone region between the average bone model and the vertebrae of the vertebra bone model of the patient, And performing spinal canal region extraction.

The step (d) includes the steps of (d-1) extracting a vertebral body region using an outline extraction method for defining a vertebra region capable of inserting a screw, and (d-2) And calculating a screw insertion path corresponding to the screw insertion path.

The step (d-1) includes the steps of extracting outlines satisfying a predetermined condition existing at a predetermined angle on both sides, and selecting an outline of the narrowest region out of the extracted outlines to generate lattice points therein can do.

The predetermined conditions include: 1) conditions for confirming whether the contour passes through the surface of the spinal canal region, 2) conditions for determining the contour only one contour per angle, and 3) if there are plural contours passing through the surface of the vertebral region, And may include conditions for selecting the outline with the largest area.

The lattice points are those existing only in the narrowest contour, and the points may be determined by the user, or may be represented by the Euclidean coordinate system by an interval based on a predetermined value.

The step (d-2) may further include: (d-2-1) performing filtering to calculate only valid paths; and (d-2-2) obtaining an optimal operation plan result . ≪ / RTI >

The step (d-2-1) includes the steps of (d-2-1-1) filtering the ineffective path to determine a surgical path inserted at a predetermined angle with respect to the sagittal plane, and (d-2-1-2 ) Performing the through-pass filtering so that the insertion path does not penetrate the axial tubular or transverse pores and thus does not damage the patient.

Wherein the average value of the points of the spinal bone model is greater than the distance of the intersection of the surgical path and the sagittal plane with respect to the projection of the average value of the points of the patient mapping bone model onto the sagittal plane, A step of extracting a path satisfying a condition that a distance between an intersection of the sagittal plane and the bone model with respect to the projection is shorter than the distance between the intersection of the sagittal plane and the bone model and determining the path as a candidate path.

The step (d-2-1-2) includes a step of extracting only two paths that occur only at two intersection points and determining the path as a candidate path when more than two intersection points occur between the patient mapping bone model and the path .

The step (D-2-2) may include a step of selecting a path having a maximum PS value in consideration of conditions related to at least one of insertion depth, safety margin, vertical direction of the screw insertion surface, and insertion of the C1 herringbone .

The insertion depth may be calculated through a distance between two intersection points between the screw insertion path and the patient mapping bone model.

The safety margin may be calculated by subtracting the radius of the selected screw from the distance to the nearest point between the screw insertion path and the patient mapping bone model.

The screw-insertion-surface vertical direction condition can be processed in such a way as to filter the vertical vector value on the articulating surface in order to prevent the insertion point on the articulating surface that may occur when considering the insertion depth condition.

The CI consecutive interpolation condition may be processed using the calculated distance between the intersection point and the boundary contour by calculating an intersection between the path of the lower contour and the boundary contour plane so that the user can control the insertion .

The step (e) includes the steps of: (e-1) selecting a screw having a predetermined size based on the contour of the narrowest vertebra, and determining whether the screw has a set safety margin value or more; (E-3) a step of selecting a screw smaller than the screw of the size and determining whether the thread has a safety margin equal to or greater than the set safety margin; and (E-1) and (e-2) are sequentially performed, and if the set safety margin value is satisfied, the procedure does not proceed to the next step Can be terminated.

In order to accomplish the above object, the present invention provides an automated optimal screw insertion path planning apparatus for safe spinal surgery, comprising: a model extraction unit extracting a spinal bone model of a patient from a medical image; Mapping unit for generating a patient mapping bone model by mapping a spinal canal region extraction unit for extracting a spinal canal region of a patient from the generated patient mapping bone model and a spinal canal region extraction unit for extracting a pedicle region from the spinal canal region of the patient And a path calculation unit for calculating a screw insertion path corresponding to the patient.

The screw insertion path planning apparatus may further include an adjustment unit that repeatedly performs the path calculation of the path calculation unit while adjusting the size of the screw and the safety margin.

According to the automated optimal screw insertion path planning method and apparatus for safe spine surgery of the present invention, a user, a spinal fusion surgery specialist, suggests a safe path for reducing the patient's injury due to various errors during surgery, It is possible to reduce the damage caused by the screw insertion of an existing carotid artery.

In addition, it is possible to propose an optimal surgical route by making a customized plan for patients having different shapes. Therefore, based on such an algorithm, it is possible not only to utilize the user as a plan for confirming the route as a preoperative plan, There is an effect that can be utilized as a navigation system.

FIG. 1 is a flowchart schematically illustrating a process of an optimal screw insertion path planning method according to an embodiment of the present invention;
2 is a diagram showing a result of local minimum point generation of registration between an average model of a cervical vertebra C2 and a patient model,
3 is a diagram showing an approximate matching result using an initialization method between an average model and a patient model,
4 is a diagram showing the results of rigid registration,
5 is a diagram showing a result of Nonrigid registration,
6 is a view showing a result of the operation of closing the spinal canal,
FIG. 7 is a diagram for explaining a process of extracting an outline of a vertebral region,
Figure 8 shows the result of creating lattice points for the narrowest vertebral contour,
9 is a diagram for explaining ineffective path filtering,
10 is a view for explaining through-hole filtering,
11 is a view showing a case where an insertion point of a screw path is located on a spinal joint surface,
Fig. 12 is a view showing a case where the C1 cervical vertebra is generated below the lateral ingot of the screw insertion fold,
13 is a view for explaining boundary extraction between the lateral mass and the arch,
FIG. 14 is a view for explaining the boundary extraction of the C1 outer mass and the arch,
15 is a diagram showing the results of the priority step of the surgical plan,
16 is a diagram showing algorithm results for C1 and C2.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

FIG. 1 is a flowchart schematically illustrating a process of an optimal screw insertion path planning method according to an embodiment of the present invention.

Referring to FIG. 1, an optimal screw insertion path planning method according to an embodiment of the present invention comprises two steps S110 and S120. The first step S110 is a spinal canal extraction step (S110) for each patient to define a pedicle region into which a screw can be inserted. In this step, registration is performed to map a three-dimensional bone data of patients having different shapes and a mapping to an average model bone containing information on the shape of one general vertebra bone. Registration can be performed to extract regions for the corresponding spinal canal of each patient from the area defined as the spinal canal in the average model bone.

The second step (S120) is to calculate the screw insertion path suitable for the patient by defining the vertebrae from the spinal canal of each patient. In order to define the vertebral body area, crossing contours of about 45 degrees on both sides can be extracted to the coronal plane of the bone center point, including the spinal canal area. At this time, in order to calculate the path of the screw insertion, the straight path needs to be defined and therefore can be defined by using one point and two angles. Therefore, a grid point is formed for the outline of the narrowest outline among the extracted outlines, and each point is used as a candidate for path generation. Also, two angles of the spherical coordinate system can be defined for each point, and each screw path candidate group can be generated. For efficient computation and efficient path generation, we remove the unwanted path through a series of filtering to obtain a valid path candidate. To find the optimal path, a perfor- mance score (PS) is assigned to each candidate path, and the optimal path is selected for the largest PS.

In more detail, the spinal canal extraction step (s110) of each patient to define the first stage pedicle region into which a screw can be inserted is (1- 1) Initialization method and (1-2) Registration step.

In addition, the second step, the thread insertion path suitable for the patient, is performed in steps S120, step 2-1, and step 2-2, trajectory computation . The final CT scan of the patient revealed the presence of screw insertion, screw insertion path, diameter and length of the insertion screw, screw insertion position, safety margin, and insertion depth, And so on. The details of the above four steps are as follows.

(1-1) Initialization step

2 is a diagram showing the results of local minimum point generation of registration between the average model and the patient model of the cervical vertebra C2.

Referring to FIG. 2, in the case of step (1-1), when registering the spinal model of the average model and the spinal model of the patient, it is used to adjust the approximate position so that the local minimum point of FIG. do.

FIG. 3 is a diagram showing an approximate matching result using an initialization method between an average model and a patient model.

Referring to FIG. 3, in order to fit an average model, a patient model, and information on shapes of two bone models, an eigenvector and an eigenvalue of a covariance of vertices of each model, ). An eigenvector can be used as a normal vector for three sagittal planes, transverse planes, and frontal planes for the bones according to the magnitude of the eigenvalues. Then, after matching the average points of the two bone models, one model is rotated through a total of eight directions (a combination of positive and negative values of three vectors), and the smallest distance between the points of the two models And the sum indicating the sum is initialized. It is possible to obtain an approximate matching result between the two models through initialization (see FIG. 3). Here, the bar of each color represents a normal vector for three planes.

(1-2) Registration step

4 is a diagram showing a Rigid registration result.

Referring to FIG. 4, in the case of step (1-2), a method of extracting the spinal canal region of each patient by associating points of the spinal canal between the average model and the patient model through registration can be used. In addition, this method can be divided into three methods in total. That is, in step (1-2-1), rigid registration is performed. In the average model and the patient model, only an average model is considered considering only three factors of scale, rotation, and translation And performs a correspondence between the two models. Through this step, more accurate matching can be performed in the initialization between the two models, and three planes (sagittal, cross-section, frontal plane) defined by the alignment in the average model can be applied to each patient's model (See Fig. 4). The upper diagrams of FIG. 4 show the results of more precisely matching the initialization results between the two models, while the lower diagrams illustrate defining three planes for the patient model.

FIG. 5 is a diagram showing the result of Nonrigid registration.

Referring to FIG. 5, nonrigid registration is performed in step (1-2-2), and unlike the rigid registration in step (1-2-1), the correspondence of patient models of different shapes . Through this process, it is possible to calculate the correspondence of the spinal canal area regardless of the difference between the patients of the vertebrae. However, since the correspondence of the points is made between the two models one by one, if the patient model has many points as compared with the average model, a more sparse correspondence may occur. Therefore, it is possible to extract more accurate spinal canal points using the closing operation for the corresponding points in step (1-2-3).

6 is a view showing the result of the close operation of the spinal canal.

Referring to FIG. 6, it is possible to extract more accurate spinal canal points by performing a closure operation on corresponding points obtained through (1-2-2). 6 shows the corresponding points of the nonrigid registration result before the closing operation and the right side of FIG. 6 shows the corresponding points after the closing operation. As a result of the closing operation, it can be seen that denser points appear more intensely in the spinal canal have.

(2-1) Extraction of the vertebral body region

FIG. 7 is a diagram for explaining an outline extraction process for a vertebra region. FIG.

7, a vertebral body region can be defined by using a set of contours starting from the spinal region of each patient model obtained in the above-described step (1-2_). The cervical vertebrae of the cervical vertebrae should be extracted from the region between 0 and 45 degrees, and the cervical vertebrae should include the transverse foramen through the carotid artery at approximately this angle. In order to extract the region, the frontal plane is changed within the angle defined above, and the intersection with the patient bone model is performed to find the points where the intersecting points occur, and the points are connected to each other At this point, we need to consider three factors because we need some rather unnecessary contours: The three elements are:

① The contour must pass the plane of the spinal canal area.

② The contour determines only one contour per angle.

③ If there are several contours passing through the face of the spinal canal area, select the outline with the largest area.

As shown in FIG. 7, as a result of performing the step (2-1), it is possible to define an empty area when viewed from the front side, and define the area into which the screw can be inserted with respect to this area. Here, the red contour represents the narrowest contour, and can be used to initialize the screw size and define the candidate group of the screw trajectory.

8 is a diagram showing the result of generating lattice points for the narrowest contour of the vertebral body.

Referring to FIG. 8, the path of the screw can be represented by a straight line. To define a straight line, one point and two angles are required. Therefore, in this method, a contour of a narrow area of a contour defining a previously defined vertebra of a point can be selected, and a lattice point can be formed within the contour to form a candidate group for each straight line. Then, by setting the angle of the spherical coordinate system as a variable for each point, it is possible to determine the optimal linear path in the preset area. The definition of the smallest contour can be used as a criterion to select smaller screws to prevent deformation of the vertebra that occurs clinically when more than 80% of the diameter of the vertebral column is inserted.

(2-2) Screw path calculation

In the case of step (2-2), a thread path is generated at the generated lattice points, and false paths that need not be considered among the path candidates are removed through two filtering to obtain correct results, Can be increased.

For filtering, there are ineffective fault filtering and penetration filtering.

① Ineffective path filtering (fault filtering)

9 is a diagram for explaining ineffective path filtering. Referring to FIG. 14, ineffective path filtering allows selection of a valid path by determining when the surgical path is too slow or too steep to insert into the sagittal plane. Screws usually take the form of the two ends of the screw being gathered in front of the vertebra through the spinal nerves of both sides, and the intersection with the sagittal plane is done outside the vertebrae. Thus, as shown in FIG. 14, P _{sag, on} the shorter distance for the P P _{sag sag,} P _{sag, on} than a distance _out of the. In this case, P _{sag, on} is the projection of the mean value of the points of the spinal model onto the sagittal plane, P _{sag, out} is the intersection of the surgical path with the sagittal plane, and P _sag is the sagittal plane, The intersection of model is shown. Therefore, only the path satisfying the condition of the expression is taken, and it is judged to be the path candidate group. This can be expressed as follows.

② Penetration filtering

10 is a view for explaining through-hole filtering. Referring to FIG. 10, when calculating the screw insertion route of the vertebrae, all that must be considered is that the penetration of the vertebrae should occur so as not to damage the patient's fatal nerve or bleeding. Therefore, in order to determine a valid path in the extracted bone model, it is necessary to determine whether the path of the thread is penetrated. Therefore, as shown in Fig. 10, in the case of a valid path, only two intersections of the path and the bone model occur. On the other hand, in the case of an ineffective path, more than two intersecting points occur because the transverse foramen resulting from the penetration and the transverse foramen passing through the artery or the spinal cord through the spinal cord lead to additional intersections. Therefore, in the through-pass filtering, only the path where two intersection points occur is judged as a path candidate group.

In order to determine how appropriate each path is for the actual insertion with the filtered path candidates, a PS is computed with a total of four elements, and the largest path is selected as the optimal path. The PS has the following four elements and adjusts parameter values according to each value to adjust for the user's preferred result. This can be expressed as follows.

Where each D represents the value of the calculated elements, and the lambda value is the value that the user is tuning. D _depth is the insertion depth, D _mg is the safety margin, D _N is the vertical direction of the screw insertion surface, and D _close is the average value of the D _{arch, i} values described below. The following explains this in turn.

① Insertion depth

It is known that the insertion depth increases clinically between the screw and the vertebra bone as the screw is deeper (Krag, Martin H., et al. "Depth of insertion of transpedicular vertebral screws into the human vertebrae: (1988): 287-294). Thus, in the previously selected path candidates, two points where a straight line meets the vertebra bone model are found, and the distance between the two points is calculated The insertion depth can be calculated.

② Safety margin

The safety margin is obtained by subtracting the radius of the screw from the distance to the nearest point between the path candidates for the previously extracted vertebral body area. The safety margin can be set by the user by setting the minimum value of the safety margin during the calculation of the algorithm.

③ Surface normal vector

11 is a view showing a case where the insertion point of the screw path is located on the spinal joint surface.

Referring to FIG. 11, when the insertion depth value is slightly overestimated in the PS function, the insertion point of the screw path can be created at the facet joint. At this time, this case can be eliminated by using the ③ element described above. That is, a normal vector for the insertion point of the bone model and a normal vector for a certain surrounding area are calculated, so that a path having a value similar to the normal vector of the joint surface can be given a penalty.

④ C1 posterior arch insertion

FIG. 12 is a view showing a case in which the C1 cervical vertebra is generated below the lateral ingot of the screw insertion fold or is generated in the posterosent.

Referring to FIG. 12, the upper diagram of FIG. 12 shows a case where the screw insertion point of the C1 cervical vertebra is generated below the lateral mass, and a lower image shows a case where the insertion point of the C1 cervical vertebra is generated in the medulla. The Harms technique, which sets the insertion point of the screw between the inferior lateral mass and the border of the posterior arch in C1 pedicle insertion, and the recent insertion of a screw in the posterior arch due to the development of pedicle screw . Therefore, this algorithm allows the user to select through the elements so that the desired insertion is possible. At this time, the following equation can be referred to.

13 is a view for explaining the boundary extraction between the outer mass and the arch. In Equation (3), d _{bound, i} is the intersection between the outline of the extracted lower outer mass and the concavo-convex of Fig. 13, and the intersection between the contour plane and the screw path is obtained. Then, the distance between the intersection point and the contour points Values. If the obtained distance values are closer to d _thres , a value of 1 is given; _otherwise , values less than 1 are given. Finally, the D _close value is defined as the average value of D _{arch, i} .

Fig. 14 is a view for explaining the boundary extraction between the C1 outer mass and the arch.

Referring to the left side of FIG. 14, the method of extracting the lower lateral masses and the hindlimb boundary can extract the frontal sides and the contours intersecting with the right and left angles at the same time as the method of extracting the vertebral body region.

The right figure of FIG. 14 shows the area of the faces according to the angles from right to left after extracting the contours intersecting the front two faces, and using the following equation (4) It is possible to select the outline of the point which is less than about 10% of the maximum area.

Equation (4) is an equation for calculating the boundary value between C1 and C2. In this case, some intersecting areas have a plurality of contours considered to be boundaries depending on the shape of the bones. Therefore, a method of selecting the contours located at the bottom of the plurality of contours is used.

Especially in case of cervical vertebrae, the width of the vertebral column is often narrow, so it may not be possible to insert the screw when planning the operation with the smallest diameter screw and sufficient safety margin. Therefore, if you are planning to reduce the diameter compared to the diameter of the initial planned screw, and if it is not possible to secure a safety margin even with a screw of the minimum diameter, insert a screw and give up the safety margin of the spinal canal . Therefore, when planning the screw insertion, plan the procedure by stepping down the screw diameter or safety clearance.

① Select a screw of about 70% size from the outline of the narrowest vertebra, and plan the surgery with a safety margin above the set value. The following is a step-by-step explanation.

(2) Select a screw smaller than the specification of the screw, and perform a surgical plan with an established safety margin.

③ In ②, if you can not plan even with the smallest diameter screw, plan the operation with the safety margin above the set value, excluding the spinal canal area in the extracted vertebral body area.

If each step does not have the result of the surgery plan, it goes to each step, and if the surgery plan is satisfied, it goes to the next step and ends the planning process. Through the above three steps, it is planned to reduce the diameter of the screw sequentially through ① ~ ②, and in the step ③, the safety margin of the spinal canal is abandoned and the artery is more importantly protected. In general, the cervical stage ③ is required, but in the case of other vertebrae it has enough width of the vertebrae, so it does not go to step ③.

15 is a diagram showing the results of the priority stage of the surgical plan.

FIG. 15 shows the results of step 3, showing that the safety margin of the spinal canal is secured and that the safety margin of the spinal canal is not secured due to the narrow vertebra.

16 is a diagram showing algorithm results for C1 and C2.

Finally, as shown in FIG. 16, the algorithm is used to calculate the surgical path, which is specific to the cervical C1-C2, and calculates the optimal path by calculating the insertion screw length, diameter, screw insertion position, path, Can be presented. In addition, when applied to other vertebrae (cervical vertebra, thoracic vertebrae, lumbar vertebrae) in the same way although the shape is somewhat different from that of C1-C2, it is also possible to calculate the optimal path by adjusting only some parameters of PS.

Using this algorithm

In this algorithm, it is possible to further increase the coupling force between the screw and the bone depending on the density of the cancerous bone, or to determine the impossibility of screw insertion due to increased osteoporosis.

Furthermore, it is possible to utilize this method as navigation to inform the operator of the information about the screw insertion by confirming and verifying the path of the spinal fusion surgery before surgery or interconnection with the medical imaging device during surgery, do.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (22)

(a) extracting a vertebral bone model of a patient from a medical image;
(b) mapping the extracted vertebrae model to an average bone model to generate a patient mapping bone model;
(c) extracting a spinal canal region of the patient from the generated patient mapping bone model; And
(d) defining a pedicle region from the spinal canal area of the patient to calculate a thread insertion path corresponding to the patient. The method according to claim 1,
(e) performing a screw margin adjustment and a safety margin adjustment, and (d) repeating the step (d). The method according to claim 1,
A method of planning an automated screw insertion route for spinal surgery, the method comprising: setting a parameter of a performance score (PS) assigned to a candidate path by an input from a user; 2. The method of claim 1, wherein step (c)
(c-1) performing initialization for primary matching between the average bone model and the vertebral bone model of the patient; And
(c-2) performing registration for extraction of the spinal canal of the patient. < Desc / Clms Page number 19 > 5. The method of claim 4, wherein the step (c-1)
And performing initialization by calculating a minimum distance value through eigenvector rotation between models using a magnitude order of eigenvalues of covariance of points of the patient's spinal bone model. Screw insertion path planning method. 5. The method of claim 4, wherein the step (c-2)
Performing spinal canal region extraction through a closing operation of the corresponding bone region between the average bone model and the vertebrae of the patient's vertebra bone model through rigid registration and non-rigid registration Wherein the method comprises the steps of: 2. The method of claim 1, wherein step (d)
(d-1) extracting a vertebral body region using an outline extraction method for defining a vertebra region capable of inserting a screw; And
(d-2) calculating a screw insertion path corresponding to the patient based on the extracted vertebral body area. 8. The method of claim 7, wherein the step (d-1)
Extracting contours satisfying a predetermined condition existing within a certain angle of both sides; And
Selecting an outline of the narrowest region out of the extracted contours to generate grid points therein. ≪ RTI ID = 0.0 > 8. < / RTI > 9. The method of claim 8,
The predetermined conditions include: 1) conditions for confirming whether the contour passes through the surface of the spinal canal region, 2) conditions for determining the contour only one contour per angle, and 3) if there are plural contours passing through the surface of the vertebral region, Wherein the step of selecting an optimal screw insertion path includes a condition for selecting the most wide area contour. 9. The method of claim 8,
Wherein the lattice points are points existing only in the narrowest contour, and each point is represented by the Euclidean coordinate system by a user or by an interval based on a preset value. . 8. The method of claim 7, wherein the step (d-2)
(d-2-1) a filtering step for selectively calculating valid paths; And
(d-2-2) obtaining an optimal surgical planning result selected by a user from among the respective routes. 12. The method of claim 11, wherein the step (d-2-1)
(d-2-1-1) filtering the ineffective path to determine a surgical path inserted at a predetermined angle with respect to the sagittal plane; And
(d-2-1-2) an automated screw insertion path planning for spinal surgery, characterized in that the insertion pathway comprises through-pass filtering to prevent damage to the patient through the axial or lateral pores Way. 13. The method of claim 12, wherein the step (d-2-1-1)
The intersection of the sagittal plane and the bone model with respect to the projection of the mean value of the points of the vertebral bone model over the sagittal plane relative to the distance of the intersection of the surgical path and the sagittal plane with respect to the projection of the mean value of the points of the patient- And determining the path as a candidate path. The method of claim 1, further comprising: 13. The method of claim 12, wherein the step (d-2-1-2)
And a step of extracting only the paths that occur only at the two intersection points and judging the candidate path as a candidate path when the intersection of more than two points between the patient mapping bone model and the path occurs. Path planning method. 12. The method of claim 11, wherein (D-2-2)
Selecting a path having a maximum PS value in consideration of a condition related to at least one of an insertion depth, a safety margin, a vertical direction of a screw insertion surface, and a C1 herringbone insertion, Path planning method. 16. The method of claim 15,
Wherein the insertion depth is calculated through a distance between two intersection points between the screw insertion path and the patient mapping bone model. 16. The method of claim 15,
Wherein the safety clearance is calculated by subtracting the radius of the selected screw from the distance to the closest point between the screw insertion path and the patient mapping bone model. 16. The method of claim 15,
Wherein the screw insertion plane vertical direction condition is processed in such a way as to filter the vertical vector values on the articular surface in order to prevent insertion points on the articular surface that may occur when considering the insertion depth condition. Automated screw insertion path planning method for spinal surgery. 16. The method of claim 15,
The CI consecutive interpolation condition is calculated by calculating an intersection point between the path of the lower outer contour and the boundary contour plane of the tragus so that the user can control the insertion and using the calculated distances between the intersection point and the boundary contour An automated screw insertion path planning method for spinal surgery. 3. The method of claim 2, wherein step (e)
(e-1) selecting a screw having a predetermined size based on the contour of the narrowest vertebra, and judging whether or not the screw has a safety margin equal to or greater than the set safety margin;
(e-2) selecting a screw smaller than the screw of the predetermined size in the specification of the screw, and judging whether or not the screw has the safety margin value set above; And
(e-3) excluding the spinal canal region in the extracted vertebral body region if surgery planning is not possible despite using the smallest diameter screw,
Wherein the step (e-1) and the step (e-2) are repeated in sequence, and if the set safety margin is satisfied, the process is terminated without proceeding to the next step. Screw insertion path planning method. A model extracting unit for extracting a vertebra bone model of the patient from the medical image;
A mapping unit for mapping the extracted vertebrae model to an average bone model to generate a patient mapping bone model;
A spinal canal region extraction unit for extracting a spinal canal region of a patient from the generated patient mapping bone model;
And a path calculation unit for defining a pedicle region from the spinal canal area of the patient and calculating a screw insertion path corresponding to the patient. 22. The method of claim 21,
Further comprising an adjustment unit that repeatedly performs path calculation of the path calculation unit while performing adjustment of a size of a screw and a safety margin.

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