CN103006335B - General calibration mould for surgical navigation and calibration method - Google Patents

Abstract

The invention relates to a general calibration mould for surgical navigation and a calibration method. The calibration mould comprises a base, and further comprises a scanning mark and a positioning mark which are arranged on the base, wherein the scanning mark consists of a geometry which can be imaged by medical imaging equipment; the geometry has feature points and/or feature lines; the feature points and/or the feature lines can determine a unique space right-angled coordinate system; and the positioning mark consists of a geometry which can be detected and tracked by positioning equipment. The calibration mould and the calibration method can be widely applied in the determination of coordinate conversional relations between the medical imaging equipment and various positioning equipment.

Description

A kind of general calibration mould of surgical navigational and scaling method

Technical field

The present invention relates to a kind of coordinate system calibration mold and scaling method, particularly about a kind of general calibration mould and scaling method of the surgical navigational for determining coordinate transformation relation between medical imaging devices and various positioning equipment.

Background technology

The surgical navigational therapy system guided based on image generally comprises the therapeutic equipments such as medical imaging devices (as ct apparatus CT, C-arm or magnetic resonance imaging device MRI), positioning equipment (as positioning camera or electromagnetic location instrument) and operating theater instruments.In operation process, the operating theater instruments by positioning equipment track and localization, under the guiding of positioning equipment, is sent to inside of human body assigned address, is treated focus by doctor exactly.Wherein, the surgical instrument position how accurately obtaining inside of human body is a key factor of impact operation.Because medical imaging devices and positioning equipment have a set of independently frame of reference separately, therefore in the operation guiding system guided based on image, top priority is exactly obtain the coordinate transformation relation between medical imaging devices and the frame of reference of positioning equipment, and this task normally completes by various types of calibration mold.

Current medical imaging devices of a great variety is design for certain specific imaging device for obtaining the calibration mold of above-mentioned coordinate transformation relation mostly, lacks versatility.It is multi-mode image-guided treatment that current clinical technology develops a trend, and therefore in how image-guided situation, operating an operation often needs to be equipped with multiple calibration mold, and apparatus relation is loaded down with trivial details and complicated.In addition, when operating theater instruments to be fixed on the needle holder can followed the tracks of by positioning equipment by doctor, also need to confirm the position relationship between the operating theater instruments end useful effect position of operating theater instruments (normally during treatment) and needle holder (operating theater instruments witness marker), this position relationship also needs could be determined by extra complicated calculations.

Summary of the invention

For the problems referred to above, the object of this invention is to provide a kind of general calibration mould and the scaling method that can determine the surgical navigational of coordinate transformation relation between dissimilar medical imaging devices and positioning equipment.

For achieving the above object, the present invention takes following technical scheme: a kind of general calibration mould of surgical navigational, is characterized in that: it comprises pedestal, and the scanning flag be arranged on described pedestal and witness marker; Described scanning flag is by being formed by the solid of medical imaging devices scanning imagery, and described solid has characteristic point and/or characteristic curve, and described characteristic point and/or characteristic curve can uniquely establish a rectangular coordinate system in space; Described witness marker is formed by being detected by positioning equipment the solid followed the trail of.

Said base is arranged some installing holes, in described installing hole, plug described scanning flag and witness marker.

Above-mentioned scanning flag is made up of three spheroids and three cylinders, described three spheroids can by CT imaging device scanning imagery, solution is filled in described cylinder, can by MRI imaging device scanning imagery, the centrage of described three cylinders intersects between two and three of centrage intersection points are just in time the centre ofs sphere of described three spheroids.

Above-mentioned scanning flag is a scalene triangle body, and certain solution is filled in described trigone inside, can by MRI imaging device scanning imagery, and described triangle physical ability is by CT imaging device scanning imagery simultaneously.

Said base surface is also provided with the needle body direction locating slot of a needle point anchor point and a linearity.

The scaling method of the general calibration mould of above-mentioned surgical navigational, it comprises the following steps:

1) coordinate of calibration mold scanning flag under imaging device is obtained

The calibration mold being provided with scanning flag and witness marker is put into medical imaging devices scan, determine scanning flag characteristic point or the coordinate of characteristic curve intersection point under imaging device, set up the orthogonal coordinate system Coord that an imaging device is relevant thus _scan, and then determine the coordinate of calibration mold scanning flag under imaging device

2) coordinate of calibration mold scanning flag under calibration mold witness marker is obtained

2.1) open positioning equipment to demarcate probe tip, by probe tip contact scanning mark, by reading the coordinate of probe tip under positioning equipment obtain scanning flag characteristic point or the coordinate of characteristic curve intersection point under positioning equipment, set up the device-dependent orthogonal coordinate system in a location Coord thus _track, and then determine the coordinate of calibration mold scanning flag under positioning equipment

2.2) from positioning equipment, read the coordinate of calibration mold witness marker under positioning equipment integrating step 2.1) obtain the coordinate of calibration mold scanning flag under calibration mold witness marker is conversed by following formula

$C_{\mathrm{mar\; ker}}^{\mathrm{refer}}={\left(C_{\mathrm{refer}}^{\mathrm{track}}\right)}^{-1}*C_{\mathrm{mar\; ker}}^{\mathrm{track}};$

3) step 1) is obtained step 2.2) obtain with substitute into following formula, obtain the coordinate transformation relation between positioning equipment coordinate system and medical imaging devices coordinate system

$C_{\mathrm{scan}}^{\mathrm{track}}=C_{\mathrm{refer}}^{\mathrm{track}}*C_{\mathrm{mar\; ker}}^{\mathrm{refer}}*{\left(C_{\mathrm{mar\; ker}}^{\mathrm{scan}}\right)}^{-1}.$

The scaling method of the general calibration mould of above-mentioned surgical navigational, it comprises the following steps:

1) open positioning equipment to demarcate probe tip, the needle point of probe is contacted with calibration mold needle point anchor point, read the coordinate of probe tip under positioning equipment obtain the coordinate of calibration mold needle point anchor point under positioning equipment read the coordinate of witness marker under positioning equipment on calibration mold simultaneously will substitute into following formula and obtain the coordinate of calibration mold needle point anchor point under calibration mold witness marker

$V_{\mathrm{locator}}^{\mathrm{refer}}={\left(C_{\mathrm{refer}}^{\mathrm{track}}\right)}^{-1}\×V_{\mathrm{locator}}^{\mathrm{track}}\text{;}$

2) by the end thereof contacts of probe tip and calibration mold direction locating slot, read the coordinate of probe tip under positioning equipment, obtain the position of an end points under positioning equipment of direction locating slot the other end of probe tip with calibration mold direction locating slot is contacted, reads the coordinate of probe tip under positioning equipment, obtain the position of another end points under positioning equipment of direction locating slot calculated direction locating slot is relative to the direction of positioning equipment thus read the coordinate of witness marker under positioning equipment on calibration mold simultaneously substitute into formula on acquisition calibration mold, direction locating slot is relative to the direction of witness marker $V_{\mathrm{orient}}^{\mathrm{refer}}=\{x,y,z,1\};$

3) operating theater instruments end is against on calibration mold needle point anchor point, reads the coordinate of witness marker under positioning equipment on needle holder simultaneously and the coordinate of calibration mold witness marker under positioning equipment will with step 1) obtain substitute into following formula and obtain the fixed position relation of operating theater instruments end relative to witness marker on needle holder

$V_{\mathrm{locator}}^{\mathrm{probe}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×C_{\mathrm{refer}}^{\mathrm{track}}\×V_{\mathrm{locator}}^{\mathrm{refer}};$

$V_{\mathrm{tip}}^{\mathrm{probe}}=V_{\mathrm{locator}}^{\mathrm{probe}};$

4) by operating theater instruments needle body and the parallel placement of calibration mold direction locating slot, read the coordinate of witness marker under positioning equipment on needle holder simultaneously and the coordinate of calibration mold witness marker under positioning equipment integrating step 2) obtain substitute into following formula and obtain the direction of operating theater instruments needle body relative to witness marker on needle holder

$V_{\mathrm{orient}}^{\mathrm{probe}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×C_{\mathrm{refer}}^{\mathrm{track}}\×V_{\mathrm{orient}}^{\mathrm{refer}},$

$V_{\mathrm{InstrumentOrient}}^{\mathrm{probe}}=V_{\mathrm{orient}}^{\mathrm{probe}}.$

The present invention is owing to taking above technical scheme, and it has the following advantages: 1, the present invention is owing to adopting the scanning flag of particular design, both can by MRI scanning imagery, also can by CT scan imaging; No matter be MRI image or CT image, one group of identical characteristic point or characteristic curve can be obtained by graphical analysis; Thus the calibration mold related in the present invention can be applicable to MRI and CT two kinds of imaging devices simultaneously.2, the calibration mold that the present invention relates to has scanning flag, witness marker, needle point anchor point and needle body direction locating slot four features, use this calibration mold can two very important position relationships in quick obtaining surgical navigational process: the position relationship between image and positioning equipment, the position relationship between operating theater instruments and positioning equipment, substantially reduce the preoperative preparation time that image guides menisectomy navigation system, for doctor has won valuable operating time.The present invention can be widely used in and determine coordinate transformation relation between different medical imaging devices and various positioning equipment.

Accompanying drawing explanation

Fig. 1 is the structural representation of calibration mold embodiment one of the present invention;

Fig. 2 is the structural representation of calibration mold embodiment two of the present invention.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is described in detail.

As shown in Figure 1 and Figure 2, calibration mold of the present invention comprises pedestal 1, and the scanning flag 2 be arranged on pedestal 1 and witness marker 3.

Scanning flag 2 is made up of plane or three-dimensional geometry body.Described solid has clear and definite characteristic point and/or characteristic curve, as leg-of-mutton three summits, and the centre of sphere of spheroid, or cylindrical axis etc.By these solid characteristic point and/or characteristic curve, a rectangular coordinate system in space uniquely can be established.When by medical imaging devices scanning scanning flag 2, can the shape information of clear display solid from medical image, obtain the coordinate of solid characteristic point or characteristic curve intersection point, and then establish the transformational relation of scanning flag relative to the medical imaging devices frame of reference.

Witness marker 3 is formed by being detected by positioning equipment the solid followed the trail of.Described solid is selected according to positioning equipment kind, can be the optical alignment ball of more than three coordinating binocular optical positioning equipment to use, and also can be one or two solenoid coordinating electromagnetic location equipment use.When witness marker 3 moves in the following range of positioning equipment, positioning equipment real-time detection witness marker 3, determines the three-dimensional coordinate of witness marker 3 relative to positioning equipment.

In above-described embodiment, pedestal can preset some installing holes, and scanning flag 2 and witness marker 3 can optionally be plugged in installing hole, determine position relationship each other, just the relative position relation of scanning flag 2 and witness marker 3 is once determine and after recording, just can not have change again.

In embodiment one, as shown in Figure 1, scanning flag 2 can be made up of three spheroids and three cylinders, described three spheroids can by CT imaging device scanning imagery, certain solution is filled in described cylinder, can by MRI imaging device scanning imagery, the centrage of described three cylinders intersects between two and three of centrage intersection points are just in time the centre ofs sphere of described three spheroids.

In embodiment two, as shown in Figure 2, scanning flag 2 can also be a scalene triangle body, and certain solution is filled in described trigone inside, can by MRI imaging device scanning imagery, and described triangle physical ability is by CT imaging device scanning imagery simultaneously.

In addition, be quick position operating theater instruments terminal position and direction in operation, pedestal 1 surface is also provided with the needle body direction locating slot 5 of needle point anchor point 4 and linearity.Needle point anchor point 4 can be the surperficial pit of pedestal 1, also can be the intersection point of cross wire.

In above-described embodiment, between needle point anchor point 4 and witness marker 3, the relative position relation between needle body direction locating slot 5 and witness marker 3 is once determine and after recording, can not have change again.

Between calibrating and positioning equipment of the present invention and medical imaging devices, the principle of position relationship is as follows:

The object of calibration mold is used to be obtain the coordinate transformation relation between the frame of reference of positioning equipment and the frame of reference of medical imaging devices according to coordinate transformation relation, following relation is had to exist:

$C_{\mathrm{scan}}^{\mathrm{track}}=C_{\mathrm{refer}}^{\mathrm{track}}*C_{\mathrm{mar\; ker}}^{\mathrm{refer}}*C_{\mathrm{scan}}^{\mathrm{mar\; ker}}$

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

In above formula, for the coordinate of calibration mold witness marker under positioning equipment; for the coordinate of calibration mold scanning flag under calibration mold witness marker, once after calibration mold completes, it is exactly a preset parameter relevant with this calibration mold; for the coordinate of calibration mold scanning flag under medical imaging devices, change according to the change of calibration mold putting position under medical imaging devices.Wherein, marker represents scanning flag, and refer represents witness marker, and track represents positioning equipment, and scan represents medical imaging devices.

According to prior art, the coordinate of calibration mold witness marker under positioning equipment directly can obtain from positioning equipment, therefore solve coordinate transformation relation key issue be how to obtain with the calibration mold being three spheroids for scanning flag below illustrates acquisition with method.

1. obtain the coordinate of calibration mold scanning flag under imaging device

1.1) calibration mold being provided with scanning flag and witness marker is put into medical imaging devices to scan.For CT imaging device, obtained the pixel of scanning flag spherome surface by three-dimensional image segmentation method, then utilize ball fitting algorithm to determine the coordinate (x of each spheroid centre of sphere under medical imaging devices _i, y _i, z _i), i=1,2,3.For MRI imaging device, the pixel of scanning flag periphery is obtained by three-dimensional image segmentation method, then utilize the centrage of cylinder fitting algorithm determination cylinder, then calculate the intersection point of centrage, namely coordinate (the x of the centre of sphere of spheroid under medical imaging devices _i, y _i, z _i), i=1,2,3.

1.2) a centre of sphere (x is selected ₁, y ₁, z ₁) as initial point O; By (x ₁, y ₁, z ₁) point to (x ₂, y ₂, z ₂) vector as x-axis, by (x ₁, y ₁, z ₁) point to (x ₃, y ₃, z ₃) vector as with reference to axle y ', will with carry out vectorial multiplication cross, the vector obtained as z-axis, will with carry out vectorial multiplication cross, the vector obtained as final y-axis, by initial point O, x-axis, y-axis, z-axis and then the unique orthogonal coordinate system of of forming that medical imaging devices is correlated with:

${\mathrm{Coord}}_{\mathrm{scan}}=\left|\begin{array}{cccc}{x}_1& y_1& z_1& o_1\\ x_2& y_2& z_2& o_2\\ x_3& y_3& z_3& o_3\\ 0& 0& 0& 1\end{array}\right|,$

The coordinate of scanning flag under medical imaging devices also correspondingly to determine.Wherein, the parameter 0 and 1 in coordinate system is the constant conveniently calculating and supplement.

2. obtain the coordinate of calibration mold scanning flag under calibration mold witness marker

2.1) open positioning equipment to utilize prior art to demarcate probe tip (to utilize prior art to demarcate the principle of probe tip will introduce below, after having demarcated, directly can obtain the coordinate of probe tip under positioning equipment wherein parameter 1 is the constant conveniently calculating and supplement), the needle point of probe is contacted with a spherome surface of scanning flag, reads the coordinate of probe tip under positioning equipment also be the coordinate of spherome surface contact point under positioning equipment, after so obtaining the some point coordinates of spherome surface, utilize ball fitting algorithm to determine the coordinate (x of this spheroid centre of sphere under positioning equipment _i, y _i, z _i), i=1,2,3.Wherein, tip represents probe tip.

2.3) adopt with step 1.2) the unique orthogonal coordinate system Coord of identical method one of forming that positioning equipment is correlated with _track, the coordinate of scanning flag under positioning equipment also determine thereupon.

2.4) from positioning equipment, read the coordinate of calibration mold witness marker under positioning equipment integrating step 2.3) obtain the coordinate of calibration mold scanning flag under calibration mold witness marker is conversed by following formula

$C_{\mathrm{mar\; ker}}^{\mathrm{refer}}=C_{\mathrm{track}}^{\mathrm{refer}}*C_{\mathrm{mar\; ker}}^{\mathrm{track}}={\left(C_{\mathrm{refer}}^{\mathrm{track}}\right)}^{-1}*C_{\mathrm{mar\; ker}}^{\mathrm{track}}.$

3. will substitute into following formula, obtain

$C_{\mathrm{scan}}^{\mathrm{track}}=C_{\mathrm{refer}}^{\mathrm{track}}*C_{\mathrm{mar\; ker}}^{\mathrm{refer}}*{\left(C_{\mathrm{mar\; ker}}^{\mathrm{scan}}\right)}^{-1}.$

Introduce below and use needle point anchor point 4 and needle body direction locating slot 5 on calibration mold to obtain the method in any operating theater instruments terminal position and direction:

First illustrate and how to obtain the position relationship of needle point anchor point relative to witness marker on calibration mold and needle body direction locating slot is relative to the direction relations of witness marker on calibration mold once calibration mold completes, with it is exactly the intrinsic parameter of calibration mold.Wherein, locator represents needle point anchor point, and orient represents needle body direction locating slot.

1) opening positioning equipment utilizes the needle point of prior art to a probe to demarcate, and is contacted by the needle point of probe with calibration mold needle point anchor point, reads the coordinate of probe tip under positioning equipment also be the coordinate of calibration mold needle point anchor point under positioning equipment read the coordinate of witness marker under positioning equipment on calibration mold simultaneously will substitute into following formula and can obtain the coordinate of calibration mold needle point anchor point under calibration mold witness marker

$V_{\mathrm{locator}}^{\mathrm{refer}}={\left(C_{\mathrm{refer}}^{\mathrm{track}}\right)}^{-1}\×V_{\mathrm{locator}}^{\mathrm{track}}.$

2) by the end thereof contacts of probe tip and calibration mold direction locating slot, the position of an end points under positioning equipment of probe tip i.e. direction locating slot is read the other end of probe tip with calibration mold direction locating slot is contacted, reads the position of another end points under positioning equipment of probe tip i.e. direction locating slot thus can calculated direction locating slot relative to the direction of positioning equipment now can read the coordinate of witness marker under positioning equipment on calibration mold utilize formula direction locating slot can be obtained on calibration mold relative to the direction of witness marker

Introduce for any operating theater instruments below, how to obtain the position of operating theater instruments end and the direction of needle body.Operating theater instruments and needle holder are fixed, needle holder are fixed a witness marker (being designated as probe) can followed the tracks of by positioning equipment:

1) operating theater instruments end is against on calibration mold needle point anchor point, reads the coordinate of witness marker under positioning equipment on needle holder simultaneously and the coordinate of calibration mold witness marker under positioning equipment will with substitution following formula obtains

$V_{\mathrm{locator}}^{\mathrm{probe}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×V_{\mathrm{locator}}^{\mathrm{tracker}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×C_{\mathrm{refer}}^{\mathrm{track}}\×V_{\mathrm{locator}}^{\mathrm{refer}}.$

Because the spatial relation of operating theater instruments end and needle holder witness marker probe is fixed, and now operating theater instruments end is against on calibration mold needle point anchor point, so have so just obtain the fixed position relation of operating theater instruments end relative to witness marker on needle holder

2) by operating theater instruments needle body and the parallel placement of calibration mold direction locating slot, read the coordinate of witness marker probe under positioning equipment on needle holder simultaneously and the coordinate of calibration mold witness marker under positioning equipment they are substituted into following formula obtain

$V_{\mathrm{orient}}^{\mathrm{probe}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×V_{\mathrm{orient}}^{\mathrm{tracker}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×C_{\mathrm{refer}}^{\mathrm{track}}\×V_{\mathrm{orient}}^{\mathrm{refer}}.$

Because the spatial relation of operating theater instruments needle body and needle holder witness marker probe is fixed, and now, operating theater instruments needle body is parallel with calibration mold direction locating slot, so have so just obtain the direction of operating theater instruments needle body relative to witness marker on needle holder

In above-described embodiment, during medical imaging devices scanning calibration mold scanning flag: in final image sequence, the distance of adjacent two images is less than or equal to 2mm; Image scanning area requirement covers whole calibration mold; The setting of sweep parameter must scanning flag in the final two-dimensional medical images of clear identification in calibration mold.

In above-described embodiment, it is prior art that unlatching positioning equipment carries out demarcation to the needle point of probe, probe is bound a witness marker, can obtain the coordinate of probe tip in the following manner:

Probe tip is against on a fixing point motionless, rotate backshank, and rotational steps is the bigger the better.In rotary course, gather the spatial parameter matrix M of witness marker _j, j=1,2,3 ... n, n are times of collection.

Calculate the principle of tip position:

Suppose that the spatial parameter matrix of fixing point under positioning equipment that probe tip is conflicted is M, probe tip is M relative to the position of witness marker _tip.

Thus have following position relationship:

$M=M_j*M_{\mathrm{tip}}=\left|\begin{array}{cc}{R}_j& T_j\\ 0& 1\end{array}\right|*\left|\begin{array}{cc}{R}_{\mathrm{tip}}& T_{\mathrm{tip}}\\ 0& 1\end{array}\right|=\left|\begin{array}{cc}{R}_j{R}_{\mathrm{tip}}& R_j{T}_{\mathrm{tip}}+T_j\\ 0& 1\end{array}\right|,$

$M=M_{j+1}*M_{\mathrm{tip}}=\left|\begin{array}{cc}{R}_{j+1}{R}_{\mathrm{tip}}& R_{j+1}{T}_{\mathrm{tip}}+T_{j+1}\\ 0& 1\end{array}\right|,$ Thus have

$\left|\begin{array}{cc}{R}_j{R}_{\mathrm{tip}}& R_j{T}_{\mathrm{tip}}+T_j\\ 0& 1\end{array}\right|=\left|\begin{array}{cc}{R}_{j+1}{R}_{\mathrm{tip}}& R_{j+1}{T}_{\mathrm{tip}}+T_{j+1}\\ 0& 1\end{array}\right|,$ Thus have

R _jt _tip+ T _j=R _j+1t _tip+ T _j+1, thus have

(R _j-R _j+1)*T _tip=(T _j+1-T _j)。

Wherein, R _jand R _j+1characterize spatial parameter matrix M _jand M _j+1in rotational component, T _jand T _j+1characterize spatial parameter matrix M _jand M _j+1in translational component, T _tipthe unknown needle point space vector to be asked, T _tipin include needle point coordinate information.By gathering n spatial parameter matrix M _j, the equation group that includes 3* (n-1) individual equation can be set up, utilize method of least square finally to determine T _tip, and then obtain the coordinate of needle point under positioning equipment

The various embodiments described above are only for illustration of the present invention, and wherein the structure, connected mode etc. of each parts all can change to some extent, and every equivalents of carrying out on the basis of technical solution of the present invention and improvement, all should not get rid of outside protection scope of the present invention.

Claims (4)

1. a general calibration mould for surgical navigational, is characterized in that: it comprises pedestal, and the scanning flag be arranged on described pedestal and witness marker; Described scanning flag is by being formed by the solid of medical imaging devices scanning imagery, and described solid has characteristic point and/or characteristic curve, and described characteristic point and/or characteristic curve can uniquely establish a rectangular coordinate system in space; Described witness marker is formed by being detected by positioning equipment the solid followed the trail of;

Described pedestal arranges some installing holes, in described installing hole, plugs described scanning flag and witness marker;

Described scanning flag is made up of three spheroids and three cylinders or described scanning flag is a scalene triangle body, when described scanning flag is made up of described three spheroids and three cylinders: described three spheroids can by CT imaging device scanning imagery, solution is filled in described cylinder, can by MRI imaging device scanning imagery, the centrage of described three cylinders intersects between two and three of centrage intersection points are just in time the centre ofs sphere of described three spheroids; When described scanning flag is described scalene triangle body: certain solution is filled in described trigone inside, can by MRI imaging device scanning imagery, and described triangle physical ability is by CT imaging device scanning imagery simultaneously.

2. the general calibration mould of a kind of surgical navigational as claimed in claim 1, is characterized in that: described base-plates surface is also provided with the needle body direction locating slot of a needle point anchor point and a linearity.

3. the scaling method of the general calibration mould of a kind of surgical navigational as described in claim 1 ~ 2 any one, it comprises the following steps:

1) coordinate of calibration mold scanning flag under imaging device is obtained

The calibration mold being provided with scanning flag and witness marker is put into medical imaging devices scan, determine scanning flag characteristic point or the coordinate of characteristic curve intersection point under imaging device, set up the orthogonal coordinate system Coord that an imaging device is relevant thus _scan, and then determine the coordinate of calibration mold scanning flag under imaging device

2) coordinate of calibration mold scanning flag under calibration mold witness marker is obtained

2.1) open positioning equipment to demarcate probe tip, by probe tip contact scanning mark, by reading the coordinate of probe tip under positioning equipment obtain scanning flag characteristic point or the coordinate of characteristic curve intersection point under positioning equipment, set up the device-dependent orthogonal coordinate system in a location Coord thus _track, and then determine the coordinate of calibration mold scanning flag under positioning equipment

2.2) from positioning equipment, read the coordinate of calibration mold witness marker under positioning equipment integrating step 2.1) obtain the coordinate of calibration mold scanning flag under calibration mold witness marker is conversed by following formula $C_{\mathrm{mar\; ker}}^{\mathrm{refer}}:$

$C_{\mathrm{mar\; ker}}^{\mathrm{refer}}={\left(C_{\mathrm{refer}}^{\mathrm{track}}\right)}^{-1}*C_{\mathrm{mar\; ker}}^{\mathrm{track}};$

3) by step 1) obtain step 2.2) obtain with substitute into following formula, obtain the coordinate transformation relation between positioning equipment coordinate system and medical imaging devices coordinate system

$C_{\mathrm{scan}}^{\mathrm{track}}=C_{\mathrm{refer}}^{\mathrm{track}}*C_{\mathrm{mar\; ker}}^{\mathrm{refer}}*{\left(C_{\mathrm{mar\; ker}}^{\mathrm{scan}}\right)}^{-1}.$

4. the scaling method of the general calibration mould of a kind of surgical navigational as claimed in claim 2, it comprises the following steps:

1) open positioning equipment to demarcate probe tip, the needle point of probe is contacted with calibration mold needle point anchor point, read the coordinate of probe tip under positioning equipment obtain the coordinate of calibration mold needle point anchor point under positioning equipment read the coordinate of witness marker under positioning equipment on calibration mold simultaneously will substitute into following formula and obtain the coordinate of calibration mold needle point anchor point under calibration mold witness marker

$V_{\mathrm{locator}}^{\mathrm{refer}}={\left(C_{\mathrm{refer}}^{\mathrm{track}}\right)}^{-1}\×V_{\mathrm{locator}}^{\mathrm{track}};$

2) by the end thereof contacts of probe tip and calibration mold direction locating slot, read the coordinate of probe tip under positioning equipment, obtain the position of an end points under positioning equipment of direction locating slot the other end of probe tip with calibration mold direction locating slot is contacted, reads the coordinate of probe tip under positioning equipment, obtain the position of another end points under positioning equipment of direction locating slot calculated direction locating slot is relative to the direction of positioning equipment thus read the coordinate of witness marker under positioning equipment on calibration mold simultaneously substitute into formula on acquisition calibration mold, direction locating slot is relative to the direction of witness marker $V_{\mathrm{orient}}^{\mathrm{refer}}=\{x,y,z,1\};$

3) operating theater instruments end is against on calibration mold needle point anchor point, reads the coordinate of witness marker under positioning equipment on needle holder simultaneously and the coordinate of calibration mold witness marker under positioning equipment will with step 1) obtain substitute into following formula and obtain the fixed position relation of operating theater instruments end relative to witness marker on needle holder

$V_{\mathrm{locator}}^{\mathrm{probe}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×C_{\mathrm{refer}}^{\mathrm{track}}\×V_{\mathrm{locator}}^{\mathrm{refer}};$

$V_{\mathrm{tip}}^{\mathrm{probe}}=V_{\mathrm{locator}}^{\mathrm{probe}};$

4) by operating theater instruments needle body and the parallel placement of calibration mold direction locating slot, read the coordinate of witness marker under positioning equipment on needle holder simultaneously and the coordinate of calibration mold witness marker under positioning equipment integrating step 2) obtain substitute into following formula and obtain the direction of operating theater instruments needle body relative to witness marker on needle holder

$V_{\mathrm{orient}}^{\mathrm{probe}}={\left(C_{\mathrm{probe}}^{\mathrm{track}}\right)}^{-1}\×C_{\mathrm{refer}}^{\mathrm{track}}\×V_{\mathrm{orient}}^{\mathrm{refer}},$

$V_{\mathrm{InstrumentOrient}}^{\mathrm{probe}}=V_{\mathrm{orient}}^{\mathrm{probe}}.$