CN202288472U - Calibration mold for medical image navigation system - Google Patents

Abstract

The utility model relates to a calibration mold for a medical image navigation system, which is characterized by comprising a calibration mold body, scanning marks arranged inside the calibration mold body and navigation marks arranged inside the calibration mold body or on the surface of the calibration mold body. The number of the scanning marks is over 3, the scanning marks are located on the same plane while not on the same straight line, the image gray level of each scanning mark is distinctly different from the image gray level of the calibration mold body, and each scanning mark is provided with a selected characteristic point. The calibration mold can be widely applied to the calibration process of the medical image navigation system.

Description

A kind of demarcation mould that is used for the medical image navigation system

Technical field

This utility model relates to a kind of demarcation mould, particularly about a kind of demarcation mould that is used for the medical image navigation system.

Background technology

In traditional operation, focus can not directly detect by an unaided eye, Minimally Invasive Surgery of for example not operating on or non-invasive procedures; Perhaps be inconvenient to detect by an unaided eye; Brain neuroblastoma surgical operation for example, the doctor can only rely on the image of perusal focus, by rule of thumb operating theater instruments is placed into the target location; Error between operation device that this mode causes and the lesions position location; Can delay the time of operation, the quality of influence operation, particularly this error are brought unnecessary painful and damage to the patient sometimes.Operation guiding system is at medical imaging device; Comprise MR imaging apparatus, ct apparatus (CT), C type arm, X line equipment, ultrasonic imaging system etc., become under the guiding of image, utilize tracking system to measure the position of operating theater instruments; Thereby can and be presented on the screen the image of focus and virtual operation instrument fusion; Help the doctor accurately to locate the position of focus and operating theater instruments, and observe perilesional organ and tissue, help the doctor to avoid important organ and tissue; Operating theater instruments is placed into the predetermined area safely, so that accomplish treatment.Operation navigation device get into surgery and with computer improve or the ability of perfect surgeon to carry out operations, reduced the damage that surgical intervention caused to a certain extent, shortened operating time.Up-to-date airmanship is focus picture and virtual operating theater instruments to be put under the same coordinate system observe; Promptly be presented at by (like the demonstration equipment of LCD screen, projection screen or other form) on the same work screen; And both relative positions are identical with the relative position of operating theater instruments with actual focus on the screen; Thereby the doctor can see focus through view screen, also can see operating theater instruments, and then accurately and apace operating theater instruments is placed into the target location.The key that image navigation operation is realized is: set up the transformational relation that is fixed between picture device coordinate system and the operating theater instruments coordinate system; For realizing this Coordinate Conversion; Need be by a caliberating device, the process of setting up transformational relation is called as the demarcation of navigation system.

Summary of the invention

To the problems referred to above, the purpose of this utility model provides a kind of demarcation mould that is used for the medical image navigation system.

For realizing above-mentioned purpose; This utility model is taked following technical scheme: a kind of demarcation mould that is used for the medical image navigation system; It is characterized in that: it comprises the demarcation mould body; Be arranged on the inner scanning flag of said demarcation mould body, be arranged on the inner or surperficial navigation marker of said demarcation mould body; The quantity of said scanning flag is more than three, and each scanning flag is positioned at the not same plane on same straight line; The gradation of image of the gradation of image of each said scanning flag and said demarcation mould body has obvious difference; Each said scanning flag all has a selected characteristic point.

Each said scanning flag is a disk, and the characteristic point of said disk is the center of circle of disk.

Each said scanning flag is a triangular plate, and the characteristic point of said triangular plate is a wherein summit of triangular plate or the center of gravity of triangular plate.

Each said scanning flag is a spheroid, and the characteristic point of said spheroid is the centre of sphere of spheroid.

Each said scanning flag is any two or more the combination in disk, triangular plate, the spheroid; The characteristic point of said disk is the center of circle of disk; The characteristic point of said triangular plate is a wherein summit of triangular plate or the center of gravity of triangular plate, and the characteristic point of said spheroid is the centre of sphere of spheroid.

This utility model is owing to take above technical scheme, and it has the following advantages: 1, the demarcation mould body set inside scanning flag of this utility model, and demarcate mould body inside or surface navigation marker is set; The quantity of scanning flag is more than three; And each scanning flag is positioned at the not same plane on same straight line; Physically limit scanning flag and be positioned on the same plane, in the scanning flag automatic parsing algorithm, can utilize this characteristic to obtain accurate more analysis result; The gradation of image of the gradation of image of each scanning flag and said demarcation mould body has obvious difference; Can conveniently carry out the image segmentation on the space; Distinguish each scanning flag, therefore, this utility model can significantly improve the fixedly computational accuracy of imaging device three-dimensional space position under navigator.2, this utility model adopts scanning flag automatic identification algorithm (obtaining the method for

described in the literary composition); Can realize the automatic calculating of scanning flag three-dimensional space position under fixing imaging device, thereby increase work efficiency greatly.This utility model is demarcated simple in structure, the preparation convenience of mould, adopts the demarcation mould of this utility model to demarcate, and can improve stated accuracy and work efficiency, therefore, can be widely used in the calibration process of medical image navigation system.

Description of drawings

Fig. 1 is that this utility model is demarcated the mould sketch map

Fig. 2 is the schematic top plan view of Fig. 1

Fig. 3 is the instantiation sketch map that this utility model is demarcated mould

Fig. 4 is the distribution schematic diagram of contiguous pixels piece in this utility model three dimensions

The specific embodiment

Below in conjunction with accompanying drawing and embodiment this utility model is carried out detailed description.

The hardware device that the medical image navigation system relates to comprises fixedly imaging device, demarcation mould, navigator.Fixedly imaging device is used for scanning demarcation mould provides medical image then.Comprise scanning flag and navigation marker in the demarcation mould, scanning flag can be fixed to the picture device scan and show clearly that on medical image navigation marker can be surveyed by navigator.Navigator is a kind of space coordinates positioning equipment, can in its effective investigative range, survey the space coordinates of navigation marker, and the positioning principle of navigator comprises multiple modes such as optical tracking, electromagnetic location.This utility model provides a kind of novel demarcation mould, can cooperate various navigator to use.

Shown in Fig. 1～3, the demarcation mould of this utility model comprises demarcates mould body 1, demarcates and is set with scanning flag 2 and navigation marker 3 on the mould body 1.

The material that the demarcation mould body 1 of this utility model is selected for use can not be fixed to the imaging of picture device scan, perhaps can be fixed to the imaging of picture device scan, but from gradation of image, with scanning flag 2 obvious difference arranged.

The scanning flag 2 of this utility model embeds demarcates mould body 1 inside, and the quantity of scanning flag 2 is more than three, and all scanning flag 2 are provided with and are located along the same line at grade and not; Each scanning flag 2 all has selected characteristic point; The thickness of each scanning flag 2 is got over Bao Yuehao, but the selection of each scanning flag 2 thickness receives the fixedly restriction of the imaging resolution of imaging device, and imaging device normal scan and from image, intuitively observing at least should be fixed.

The navigation marker 3 of this utility model can be arranged on the surface of demarcating mould body 1 according to the difference of selected navigator, also can be embedded into and demarcate in the mould body 1.Fig. 1, Fig. 2 have only shown the coordinate signal of navigation marker 3, and the profile of navigation marker 3 is not in this utility model protection domain, and its profile is relevant with the navigator of being selected for use.

As shown in Figure 3, be to demarcate a specific embodiment of mould, wherein scanning flag 2 is embedded into and demarcates in the mould body 1, be arranged on the plane, and conllinear not.Navigation marker 3 also is embedded into simultaneously to be demarcated in the mould body 1.Cover a pressing plate on scanning flag 2 and the navigation marker 3, navigation marker 2 and scanning flag 3 are fixed on demarcate in the mould body 1.

In the foregoing description, each scanning flag 2 of demarcating on the mould body 1 can be arranged on the disk on the same plane, can also be the scanning flag of other shapes such as triangular plate, spheroid; It also can be any two or more the combination in the scanning flag of other shapes such as disk, triangular plate, spheroid.The common ground of scanning flag is: from medical image, can clearly discern; And has selected characteristic point; Characteristic point such as disk is the center of circle of disk; The characteristic point of triangular plate is a wherein summit of triangular plate or the center of gravity of triangular plate, and the characteristic point of spheroid is the centre of sphere of spheroid etc., and these characteristic points can be obtained from image sequence through automatic parsing algorithm automatically.

Utilize the demarcation mould of this utility model to realize that the scaling method of image-guidance comprises following content.

As shown in table 1, when utilizing the demarcation mould of this utility model to realize the scaling method of image-guidance, each variable-definition that relates to is following:

Table 1

Utilize the demarcation mould of this utility model to realize that the purpose of the scaling method of image-guidance is to obtain fixedly the coordinate of imaging device under navigator according to coordinate transformation relation, can infer:

$C_{\mathrm{scan}}^{\mathrm{track}}=C_{\mathrm{refer}}^{\mathrm{track}}*C_{\mathrm{marker}}^{\mathrm{refer}}*C_{\mathrm{scan}}^{\mathrm{marker}}$

$C_{\mathrm{scan}}^{\mathrm{track}}=C_{\mathrm{refer}}^{\mathrm{track}}*C_{\mathrm{marker}}^{\mathrm{refer}}*{\left(C_{\mathrm{marker}}^{\mathrm{scan}}\right)}^{-1}$

Demarcate in the mould and comprise the navigation marker that navigator can be surveyed; Therefore; The coordinate

of navigation marker under navigator can directly obtain from navigator, need not complicated calculations.Utilize the demarcation mould of this utility model to realize in the scaling method of image-guidance; The method of obtaining

and is provided, thereby finally can have calculated

One, obtaining need analyze the characteristic point position of each scanning flag automatically, and its step is following.

The requirement of automatic parsing algorithm: 1. the quantity of scanning flag must be more than three; 2. all scanning flag must be placed on the plane; 3. each scanning flag can not be positioned on the straight line; 4. each scanning flag must be able to be fixed to the picture device scan, and on gradation of image, distinguishes to some extent with surrounding structure.

Known conditions 1: demarcate mould through after being fixed into the picture device scan, according to material that each scanning flag the adopted imaging features under fixing imaging device, can access the gradation of image value interval that each scanning flag is directed against and be (Pixel1, Pixel2).

Known conditions 2: demarcate total n scanning flag in the mould, any scanning flag a is to the distance B between any scanning flag b _AbKnown.

Known conditions 3: the fixedly sweep spacing of imaging device demixing scan is set, carries out demixing scan, obtain an image sequence to demarcating mould; Comprise K and open image; Every image comprises I * J pixel, an always total I * J * K pixel, each pixel corresponding gray and space coordinates (x; Y is known z).

Definition 1: space contiguous pixels piece: the gray value of any pixel in the contiguous pixels piece is greater than 0, and any two pixels can couple together through successive pixel in twos; There is not contiguous pixels between two contiguous pixels pieces, otherwise should be regarded as a contiguous pixels piece.

The step of obtaining through automatic parsing algorithm is following:

1) to demarcating the mould image sequence; Utilizing the gradation of image value that scanning flag is directed against, interval (Pixel1 Pixel2) carries out gray scale to image sequence and cuts apart, and the gray value of the pixel outside the interval all is changed to 0; The gray value of the pixel that the interval is interior all is changed to the fixed value of a certain non-zero, as 255.In I * J * K pixel, travel through, search space contiguous pixels piece, obtain n+m contiguous pixels piece; Wherein, n representes to have n scanning flag piece 4, and m representes to have m noise piece 5 (as shown in Figure 4); Wherein, n scanning flag piece 4 should be positioned on the same plane in theory.

2) according in the known conditions 3, and the space coordinates of each pixel correspondence (x, y, z), the space coordinates (x of i contiguous pixels piece of computer memory _i, y _i, z _i); Suppose to comprise in the contiguous pixels piece f pixel, so:

$x_i,y_i,z_i=\frac{\underset{j=1}{\overset{f}{\mathrm{\Σ}}}{x}_{\mathrm{ij}},y_{\mathrm{ij}},z_{\mathrm{ij}}}{f}$

Wherein, (x _Ij, y _Ij, z _Ij) space coordinates of j pixel in i contiguous pixels piece of expression.

3) according to the space coordinates (x of i the contiguous pixels piece in space _i, y _i, z _i), can calculate the distance of any two contiguous pixels interblocks:

$d_{\mathrm{ab}}=\sqrt{{(x_a-x_b)}^2+{(y_a-y_b)}^2+{\left(z_a{-z}_b\right)}^2}$

According to the distance B between known any two scanning flag _AbAnd between any two contiguous pixels pieces apart from d _Ab,, can from n+m contiguous pixels piece, isolate n scanning flag through apart from comparison algorithm.

4) coordinate and n the scanning flag according to each pixel in an isolated n scanning flag, the n scanning flag is positioned on the same plane; All pixels in n the scanning flag that obtains are done plane fitting one time; Thereby obtain fit Plane, plane equation is:

Ax+By+Cz＝d

5) subpoint of each pixel on the Ax+By+Cz=d of plane in n scanning flag of calculating, these all subpoints have formed a planar graph, comprise n scanning flag in the figure.

6) in the planar graph that from step 5), obtains, be partitioned into the border of n scanning flag, find the characteristic point of scanning flag; According to the characteristic point coordinates of the n that an obtains scanning flag, calculate each scanning flag coordinate

under fixing imaging device as a whole

Adopt disk as special case below; Introduce scanning flag how in step 6), to obtain

other types; Like triangular plate etc., can carry out with reference to following steps.In the planar graph that from step 5), obtains; Use image Segmentation Technology to obtain the border of n approximate circle; Match is justified on border to n approximate circle; Obtain n the center of circle; Be the characteristic point of disk, according to the central coordinate of circle of the n that an obtains disk, the step of the coordinate under fixing imaging device is following as a whole to calculate each scanning flag:

1. select first disk center of circle (x ₁, y ₁, z ₁) as initial point o;

2. calculate point to second disk center of circle from first disk center of circle vector as the x axle,

3. with the coordinate figure of all the other each disk centre points; Average; Obtain p ' point; Calculate first disk center of circle and point to p ' vector y axle as a reference,

4.

and

carried out vectorial multiplication cross; The vector that obtains is as the z axle,

5. and

carried out vectorial multiplication cross; The vector that obtains is as final y axle,

6. through initial point o, x axle, y axle, z axle; Form coordinate system, obtain each scanning flag coordinate

under fixing imaging device as a whole

Two, utilize the demarcation mould of this utility model to realize that the step of obtaining

is following in the scaling method of image-guidance.

1) opens navigator; On a probe, bind another navigation marker; According to existing method; Probe tip is demarcated, thereby can from navigator, directly be obtained the coordinate of probe tip under navigator

2) characteristic point with probe tip and each scanning flag contacts, and reads

Because the characteristic point of needle point and scanning flag contacts, also just obtain the coordinate (x of characteristic point under navigator of each scanning flag simultaneously _i, y _i, z _i) (1≤i≤n).

3) according to the coordinate (x of characteristic point under navigator of each scanning flag _i, y _i, z _i) (1≤i≤n), calculate each scanning flag coordinate under navigator as a whole

4) from navigator, read the coordinate

of navigation marker under navigator

5) basis $C_{\mathrm{Marker}}^{\mathrm{Refer}}=C_{\mathrm{Track}}^{\mathrm{Refer}}*C_{\mathrm{Marker}}^{\mathrm{Track}}={\left(C_{\mathrm{Refer}}^{\mathrm{Track}}\right)}^{-1}*C_{\mathrm{Marker}}^{\mathrm{Track}},$ Obtain each scanning flag coordinate under navigation marker as a whole

Adopt disk as special case below; Introduce scanning flag how in step 3), to obtain

other types; Like triangular plate etc., can carry out with reference to following steps.The characteristic point of disk is the center of circle; Then utilize the coordinate of the center of circle under navigator of each disk, the step of the coordinate under navigator is following as a whole to calculate each scanning flag:

1. select first disk center of circle (x ₁, y ₁, z ₁) as initial point o;

2. calculate point to second disk center of circle from first disk center of circle vector as the x axle,

3. with the coordinate figure of all the other each disk centre points; Average; Obtain p ' point; Calculate first disk center of circle and point to p ' vector y axle as a reference,

4.

and

carried out vectorial multiplication cross; The vector that obtains is as the z axle,

5.

and carried out vectorial multiplication cross; The vector that obtains is as final y axle,

6. through initial point o, x axle, y axle, z axle; Form coordinate system, obtain each scanning flag coordinate under navigator as a whole

Enumerate the demarcation mould that utilizes this utility model below and realize a specific embodiment of the scaling method of image-guidance.

1) at first 4 disks and navigation marker are fixed on the demarcation mould according to related request; should demarcate at first according to the method for above-mentioned introduction as the inner parameter of demarcating mould.

2) will demarcate mould and put into fixedly that imaging device scans.Scanning requires: the fixedly sweep spacing of imaging device demixing scan is set, makes the distance of adjacent two picture centres in the final image sequence as much as possible little (get final product greater than 0, obtain more image about scanning flag as far as possible); The image scanning area requirement covers the whole calibrating mould; The setting of sweep parameter must make can see the scanning flag of demarcating the mould clearly on final two-dimensional medical images.

3) obtain the image sequence of demarcating mould behind the end of scan, obtain

according to the above-mentioned method that provides

4) according to formula $\begin{array}{c}{C}_{\mathrm{Scan}}^{\mathrm{Track}}=C_{\mathrm{Refer}}^{\mathrm{Track}}*C_{\mathrm{Marker}}^{\mathrm{Refer}}*C_{\mathrm{Scan}}^{\mathrm{Marker}}\\ C_{\mathrm{Scan}}^{\mathrm{Track}}=C_{\mathrm{Refer}}^{\mathrm{Track}}*C_{\mathrm{Marker}}^{\mathrm{Refer}}*{\left(C_{\mathrm{Marker}}^{\mathrm{Scan}}\right)}^{-1}\end{array},$ Calculate final result

Accomplish and demarcate.

In the foregoing description; The method of obtaining

is a kind of instance; According to the difference of navigator, there is the method for other calculating

.

Above-mentioned each embodiment only is used to explain this utility model; Wherein the structure of each parts, connected mode etc. all can change to some extent; Every equivalents of on the basis of this utility model technical scheme, carrying out and improvement all should not got rid of outside the protection domain of this utility model.

Claims (5)

1. demarcation mould that is used for the medical image navigation system, it is characterized in that: it comprises the demarcation mould body, is arranged on the inner scanning flag of said demarcation mould body, is arranged on the inner or surperficial navigation marker of said demarcation mould body; The quantity of said scanning flag is more than three, and each scanning flag is positioned at the not same plane on same straight line; The gradation of image of the gradation of image of each said scanning flag and said demarcation mould body has obvious difference; Each said scanning flag all has a selected characteristic point.

2. a kind of demarcation mould that is used for the medical image navigation system as claimed in claim 1, it is characterized in that: each said scanning flag is a disk, and the characteristic point of said disk is the center of circle of disk.

3. a kind of demarcation mould that is used for the medical image navigation system as claimed in claim 1, it is characterized in that: each said scanning flag is a triangular plate, and the characteristic point of said triangular plate is a wherein summit of triangular plate or the center of gravity of triangular plate.

4. a kind of demarcation mould that is used for the medical image navigation system as claimed in claim 1, it is characterized in that: each said scanning flag is a spheroid, and the characteristic point of said spheroid is the centre of sphere of spheroid.

5. a kind of demarcation mould that is used for the medical image navigation system as claimed in claim 1; It is characterized in that: each said scanning flag is any two or more the combination in disk, triangular plate, the spheroid; The characteristic point of said disk is the center of circle of disk; The characteristic point of said triangular plate is a wherein summit of triangular plate or the center of gravity of triangular plate, and the characteristic point of said spheroid is the centre of sphere of spheroid.

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