CN102846337A - Three-dimensional ultrasound system, method and device for positioning target point of three-dimensional ultrasound system - Google Patents

Abstract

The invention discloses a three-dimensional ultrasonic system and its target point positioning method and device. Considering the sound field thickness factor, the target point is scanned multiple times from different directions to obtain the coordinates of the target point in the ultrasonic scanning space; according to the correlation of each direction The projection of the measurement assigns weights to each scan; calculates the coordinates of the target point in the reference space according to the weight and the transformation matrix from the coordinates of each ultrasound scan space to the reference space; uses the pre-acquired transformation matrix from the ultrasound scan space to the world coordinate space Transform the coordinates of the target point in the reference space to the world coordinate space. The invention uses the axial and lateral errors with high ultrasonic space precision to make up for the thickness error with low precision, thereby improving the positioning precision of the target point in the ultrasonic scanning space.

Description

The localization method of 3 D ultrasound system and impact point thereof and device

Technical field

The present invention relates to a kind of 3 D ultrasound system, relate in particular to localization method and the device of the impact point of 3 D ultrasound system.

Background technology

3 D ultrasound system is in fusion of imaging, surgical navigational, biopsy and the application in field such as to melt more and more, and it is more directly perceived than two-dimensional ultrasonic image, and comprises more time and space shape information.The advantages such as the 3 D ultrasound system based on free arm (freehand) is more flexible than mechanical 3 D ultrasound system, has arbitrarily angled scanning, and mobile space is unrestricted.Freedom-arm, three-D ultrasonic system commonly used has: based on the freedom-arm, three-D ultrasonic system of electromagnetic transducer; Freedom-arm, three-D ultrasonic system based on active light/passive optical sensor.Three-dimensional scaling is important in a freedom-arm, three-D ultrasonic system link, refer to by someway or the device, determine the transformation relation between each space coordinates in the 3 D ultrasound system.Know the transformation relation between each space coordinates, with ultrasonic scanning localizing objects point, the coordinate of ground point of plane of ultrasound is through coordinate transform, from the ultrasonic scanning spatial alternation to sensor space, position, transform to again world space, thereby know impact point in the position of world space, for ultrasonic fusion of imaging, surgical navigational etc. provide positional information.An important step is with the point of the point on the ultrasonoscopy and another modal data corresponding registration one by one in ultrasonic fusion of imaging, its essence is with impact point in world coordinates the position and another modal data in the position of impact point be mapped, accurately obtain the position of impact point in world coordinates and have a significant impact improving registration accuracy.

The acoustic beam relevant with 3 D ultrasound system has error in three directions: axial error, lateral error, thickness error.

Axial error (axial): the error on the ultrasonic beam axis, relevant with wavelength in theory, only have when 2 distances greater than wavelength 1/2 the time, ultrasonicly could produce respectively two echoes, equal can differentiate on the ultrasonic beam axis minimum range of point-to-point transmission.

Lateral error (lateral): claim again lateral error, the error vertical with axial direction, it and focal position, axial depth, the aperture, the ultrasonic beam diameter, multi-beam is synthetic relevant.Horizontal direction direction perpendicular to axial direction is in the ultrasonic scanning plane that axially coexists.

Thickness error (elevational, thickness): the error on the plane of ultrasound thickness direction, it and probe crystal oscillator, the geometry of acoustic lens, axial depth is relevant.Thickness direction and axial direction, lateral are mutually vertical.

Technology has been ignored the thickness of ultrasonic sound field at present, regards the ultrasonic scanning space as X to the conversion in sensor space, position _Usz=0 2D plane is to the conversion of 3d space, the X here _UszThe coordinate of the ultrasonic imaging space thickness direction (can be expressed as Z axis) that refers to.

But in actual applications, because ultrasonic beam itself has certain thickness, simultaneously the characteristics of ultrasonic beam far field diversity are not so that ultra sonic imaging is the situation in a unlimited thin cross section of reflection but the plane that certain thickness arranged and disperse gradually, on the stricti jurise, because the thickness of ignoring ultrasonic sound field causes the inaccurate of location, and then affect the precision of ultrasonic fusion of imaging and surgical navigational.

During ultrasonic scanning, because the physical characteristic of probe determines that the error of ultrasonic all directions is not identical.Axially and lateral error less, the thickness direction error is larger.In the two-dimensional ultrasound system, what mainly pay close attention to is axial and lateral error, more to the optimization of axial and lateral error, less to the concern of thickness direction error, and optimization is less or not optimization also.Mostly do not consider sound field thickness factor in the present freedom-arm, three-D ultrasonic system, but in 3 D ultrasound system the impact of thickness error than axially and lateral error much larger.Although some technology has been considered sound field thickness factor, it reduces the impact that thickness error brings by special device, uses very inconvenient.

Summary of the invention

The main technical problem to be solved in the present invention is, localization method and the device of a kind of 3 D ultrasound system and impact point thereof is provided, and sound field thickness factor is taken into account, and impact point is demarcated, and improves the positioning accuracy of impact point.

According to an aspect of the present invention, provide a kind of object location method of 3 D ultrasound system, comprising:

This impact point is at the coordinate in each ultrasonic scanning space when obtaining ultrasonic probe and repeatedly same impact point being scanned from different directions;

Select a ultrasonic scanning space as the reference space, with all ultrasonic scanning space coordinatess of obtaining behind the Multiple-Scan to this with reference to space projection, obtain each ultrasonic scanning space coordinates to this transformation matrix with reference to the space;

Correlated measure according to all directions assigns weight for each time scan-data;

Calculate impact point at the coordinate in reference space according to weight and each ultrasonic scanning space coordinates to this transformation matrix with reference to the space;

Utilize the transformation matrix from the ultrasonic scanning space to the world coordinates space that obtains in advance with impact point in the coordinate transform in reference space to the world coordinates space.In one embodiment, when described correlated measure according to all directions assigns weight for each time scan-data according to following rule: the component of weight on axial direction, lateral or thickness direction, estimating the projected size that makes progress the party according to corresponding scan-data determines, for the less weight of scan-data distribution of the large direction of correlated measure projection, be that the scan-data of the little direction of correlated measure projection distributes larger weight.

The coordinate of impact point in the reference space adopts following formula to calculate:

$X_{\mathrm{usref}}^{\′}=\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_j(T_{\mathrm{usref}\_\mathrm{usj}}\·X_{\mathrm{usj}})$

Wherein, X ' _UsrefBe impact point at the coordinate in reference space, N is the scanning times to same impact point, α _jThe weight vectors of the j time scan-data, T _{Usred_usj}That the j time ultrasonic scanning space is to the transformation matrix with reference to the space, X _UsjThe original coordinates that is impact point in the j time ultrasonic scanning space.

According to a further aspect in the invention, a kind of object location device of 3 D ultrasound system is provided, be used for impact point from the ultrasonic scanning spatial alternation to the world coordinates space, described device comprises: original coordinates obtains the unit, obtains this impact point at the coordinate in ultrasonic scanning space for the ultrasonoscopy from each scanning when ultrasonic probe scans same impact point from different directions; Projecting cell be used for to select a ultrasonic scanning space as the reference space, with all ultrasonic scanning space coordinatess of obtaining behind the Multiple-Scan to this with reference to space projection, obtain each ultrasonic scanning space coordinates to this transformation matrix with reference to the space; The weight allocation unit is used for assigning weight for each time scan-data according to the correlated measure of all directions; The coordinate modification unit is used for calculating impact point at the coordinate in reference space according to weight and each ultrasonic scanning space coordinates to this transformation matrix with reference to the space; Coordinate transformation unit, be used for to utilize the transformation matrix from the ultrasonic scanning space to the world coordinates space that obtains in advance with impact point in the coordinate transform in reference space to the world coordinates space.

The present invention also provides a kind of 3 D ultrasound system simultaneously, comprising: ultrasonic probe is used for to those who are investigated's target site emission ultrasound wave; The supersound process module is used for the echo-signal that receives is processed, and obtains the ultrasonoscopy of target site; Caliberating device for detection of the locator data of ultrasonic probe, and is demarcated ultrasonoscopy and locator data, obtains the transformation matrix from the ultrasonic scanning space to the world coordinates space; Data computation module is used for demarcating the data reconstruction of getting well or with other modal data registration, and the ultrasonoscopy at export target position and/or data, and described data computation module comprises above-mentioned object location device; Display module is used for ultrasonoscopy and the data of target site are shown.

The present invention is by the projection of ultrasonic scanning different directions correlated measure on the reference space, distribute different weights, axial and the lateral error higher with the ultrasonic scanning spatial accuracy remedies the low thickness error of precision, thereby improves impact point in the positioning accuracy in ultrasonic scanning space.

Description of drawings

Fig. 1 is the block diagram of 3 D ultrasound system in an embodiment of the present invention;

Fig. 2 is the spatial alternation relation of freedom-arm, three-D ultrasonic system in an embodiment of the present invention;

Fig. 3 is the structured flowchart of object location device in an embodiment of the present invention;

Fig. 4 is the positioning flow figure of impact point in an embodiment of the present invention;

Fig. 5 is Multiple-Scan impact point schematic diagram in an embodiment of the present invention.

The specific embodiment

By reference to the accompanying drawings the present invention is described in further detail below by the specific embodiment.

In the application's embodiment, sound field thickness factor is taken into account, simultaneously combined echocardiography axially and lateral error by measuring target point repeatedly, is given different weights, obtains the accurate world space coordinate of impact point.When localizing objects point, ultrasonic probe carries out Multiple-Scan to same impact point from a plurality of directions, and after being scanned at every turn this impact point at the coordinate in ultrasonic scanning space and the transformation matrix between the different coordinate space.With other ultrasonic scanning space coordinates to one of them ultrasonic scanning space projection (perhaps with all ultrasonic scanning spaces to a new space projection), according to relevant the estimating of certainty of measurement (being called for short " correlated measure "), be assigned to different weights, obtain revising rear impact point after the weighted sum at the coordinate figure in reference space.Transform to world coordinates with revised with reference to spatial value again, thereby the axial and lateral error higher with the ultrasonic scanning spatial accuracy remedies the low thickness error of precision, reduced the error of sound field thickness direction, the coordinate of the impact point that obtains is also more accurate, has improved follow-up ultrasonic fusion of imaging mid point to registration accuracy.

Among a kind of embodiment, the block diagram of freedom-arm, three-D ultrasonic system as shown in Figure 1: 3 D ultrasound system comprises ultrasonic probe 101, supersound process module 104, caliberating device 100, data computation module 106 and display module 107.Ultrasonic probe 101 is used for to those who are investigated's target site emission ultrasound wave; Supersound process module 104 is used for the echo-signal that receives is processed, and obtains the ultrasonoscopy of target site; Caliberating device 100 is used for carrying out three-dimensional scaling, namely passes through someway or device, determines the transformation relation between each space coordinates in the 3 D ultrasound system.In one embodiment, caliberating device 100 comprises position sensor, register control and demarcating module, and position sensor is used for the positional information of detecting ultrasonic probe, for example comes the pop one's head in position sensor 102 of 101 locus of detecting ultrasonic by magnetic or light.In one embodiment, position sensor 102 comprises an emitter and a receptor, the receptor of its Position Sensor 102 is fixed on the probe 101, the emitter of position sensor 102 then is fixed near the imaging position (diagnosis position), and along with the movement of popping one's head in, constantly provide positional information by receptor and the relative bearing between the emitter that records.Register control 103 is used for obtaining according to the positional information of ultrasonic probe the locus of ultrasonic probe; Demarcating module 105 is used for ultrasonoscopy and locator data are demarcated.

Transformation relation between the space coordinates comprises the transformation relation from the ultrasonic scanning space to sensor space, position, from the position sensor space to the transformation relation the world coordinates space, and the spatial alternation of freedom-arm, three-D ultrasonic system as shown in Figure 2 relation.Space coordinate transformation closes:

X _w＝T _{w_s}·T _{s_us}·X _us -------------------------------(1)

X wherein _UsThat point is at the coordinate in ultrasonic scanning space, X _wThat point is at the coordinate of world's coordinate space, T _{S_us}That the ultrasonic scanning space is to the transformation matrix in sensor space, position, T _{W_s}That the position sensor space is to the transformation matrix in world coordinates space.Position sensor be fixed on probe upper motionless, when ultrasound parameter is constant, T _{S_us}Immobilize.T _{W_s}Obtained by register control and position sensor, along with the movement of probe, T _{W_s}Constantly change.

After the transformation relation of knowing between each space coordinates, it is available ultrasonic scanning localizing objects point, the coordinate of ground point of plane of ultrasound is through coordinate transform, from the ultrasonic scanning spatial alternation to sensor space, position, transform to again world space, thereby know that impact point is in the position of world's coordinate space.

The impact point that data computation module 106 namely is used for ultrasonic scanning is obtained is from the ultrasonic scanning spatial alternation to the world coordinates space, is used for demarcating the data reconstruction of getting well or with other modal data registration, and the ultrasonoscopy at export target position and data; The ultrasonoscopy of the target site that data computation module 106 obtains and data and some functional parameters output to display module 107 and show.In embodiments of the present invention, data computation module 106 comprises the object location device, and the object location device is used for more accurately localizing objects point, thus more accurately with impact point from the ultrasonic scanning spatial alternation to the world coordinates space.

In the prior art, in calibration process, do not consider the thickness of ultrasonic sound field, X _UsThere is certain error, for the impact point that makes acquisition more accurate at the coordinate in ultrasonic scanning space, in an embodiment of the present invention, as shown in Figure 3, the object location device comprises that original coordinates obtains unit 301, projecting cell 302, weight allocation unit 303, coordinate modification unit 304 and coordinate transformation unit 305.Original coordinates obtains unit 301 and is used for obtaining impact point at the coordinate in ultrasonic scanning space from ultrasonoscopy when ultrasonic probe scans impact point from different directions; Projecting cell 302 is used for selecting a ultrasonic scanning space as the reference space, with all ultrasonic scanning space coordinatess of obtaining behind the Multiple-Scan to this with reference to space projection, obtain each ultrasonic scanning space coordinates to this transformation matrix with reference to the space; Weight allocation unit 303 is used for assigning weight for each time scan-data according to the correlated measure of all directions, in one embodiment, according to following regular allocation weight: weight in a direction (for example, axial direction, lateral or thickness direction) on component, determine in the projected size that the party makes progress according to corresponding scan-data correlated measure, for the less weight of scan-data distribution of the large direction of correlated measure projection, be that the scan-data of the little direction of correlated measure distributes larger weight.Coordinate modification unit 304 is used for calculating impact point at the coordinate in reference space according to weight and each ultrasonic scanning space coordinates to this transformation matrix with reference to the space; Coordinate transformation unit 305 utilizes the ultrasonic scanning space of in advance acquisition to the transformation matrix T in sensor space, position _{S_us}, and the transformation matrix T from the position sensor space to the world coordinates space that is obtained in advance by caliberating device 100 _{W_s}, impact point is arrived the world coordinates space in the coordinate transform in reference space.

In one embodiment, the coordinate of impact point in the reference space adopts following formula to calculate:

$X_{\mathrm{usref}}^{\′}=\underset{j=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_j(T_{\mathrm{usref}\_\mathrm{usj}}\·X_{\mathrm{usj}})---\left(2\right)$

Wherein, X ' _UsrefBe impact point at the coordinate in reference space, N is scanning sum, α _jThe weight vectors of the j time scan-data, T _{Usref_usj}That the j time ultrasonic scanning space is to the transformation matrix with reference to the space, X _UsjThe original coordinates that is impact point in the j time ultrasonic scanning space.Wherein, can be any one ultrasonic scanning space with reference to the space, for example can be the ultrasonic scanning space of certain scanning, also can be the space new with irrelevant one in scanning direction.

Based on the 3 D ultrasound system of above-mentioned 3 D ultrasound system and object location device, in one embodiment, the object location method may further comprise the steps as shown in Figure 4:

Step S1, from different directions, the same impact point of Multiple-Scan, each scanning direction namely consists of a ultrasonic scanning space, obtain impact point at the coordinate in this ultrasonic scanning space after each scanning, caliberating device 100 obtains the transformation matrix between each coordinate space simultaneously, and for example the ultrasonic scanning space is to the transformation matrix in sensor space, position, and the position sensor space is to the transformation matrix in world coordinates space.For example carry out N scanning, N is the integer greater than 1.Scan mode can be twice sweep, and the twice sweep direction is as far as possible vertical; Also can be repeatedly a plurality of scanning directions, each scanning direction is run-down at least; The scanning direction can be to divide equally as far as possible, also can be the ultrasonic scanning that any direction is not divided equally.

Step S2, in N scanning, select wherein once (for example the i time) ultrasonic scanning space as the reference space, with other N-1 time scanning coordinate to the i time ultrasonic scanning space projection, and obtain each ultrasonic scanning space coordinates to this transformation matrix with reference to the space, wherein, N is scanning times, and i is the sequence number in the ultrasonic scanning space that is projected, 1≤i≤N.

Step S3 gives different weights according to estimate (the abbreviation correlated measure) relevant from certainty of measurement on each scanning direction to each scan-data.In the different ultrasonic scanning spaces, has different certainties of measurement on the different directions, this is to be determined by the precision of instrument, correlated measure can be following physical quantity: error, variance or resolution, certainly, those skilled in the art can also be as required be defined as correlated measure with other the physical quantity relevant with certainty of measurement.Give different weights according to correlated measure to scan-data, if correlated measure is larger in this direction, then should make this direction little on the final result impact, the weight of distribution should be less; If correlated measure is less in this direction, then should make this direction large on the final result impact, the weight of distribution also should be larger.

Step S4, according to weight and each ultrasonic scanning space coordinates to this transformation matrix with reference to the space recomputate impact point in the i time ultrasonic scanning space namely with reference to the coordinate X ' in space _UsiIn one embodiment, obtain new coordinate figure X ' by weighted sum _Usi, shown in (2):

X′ _usi＝α ₁·(T _{usi_us1}·X _us1)+…+α _i·X _usi++…+α _N·(T _{usi_usN}·X _usN)-------(3)

Wherein: X ' _UsiThat impact point is at the correction coordinate in the i time ultrasonic scanning space, α ₁, α ₂... α _NThe weight vectors of each time scan-data, T _{Usi_usN}That the N time ultrasonic scanning space obtaining in advance is to the transformation matrix in the i time ultrasonic scanning space, X _UsiThe original coordinates that is impact point in the i time ultrasonic scanning space.

Be situation with reference to the space for the i time ultrasonic scanning space of definition, impact point is at the correction coordinate X ' in the i time ultrasonic scanning space _UsiBe impact point at the coordinate in reference space.

Step S5 uses the scan conversion matrix again the i time, with the coordinate figure X ' of impact point in the reference space _UsiTransform to the world coordinates space by formula (1), thereby obtain impact point more accurate coordinate figure in world's coordinate space.

In one embodiment, inverse ratio according to the projection of correlated measure (for example error/variance) is that scan-data is given different weights, divides for the large direction of correlated measure projection to be equipped with little weight, and the little direction of correlated measure projection is distributed large weight, weight meets normalization, namely Thereby it is little that large the estimating of error affected final result, and estimating the final result impact that error is little is large, makes the impact point that obtains revise coordinate in world's coordinate space more accurate.

For each ultrasonic scanning, the inventor finds to exist following characteristics, that is: ultrasonic thickness direction precision is low, and the precision of axial and side direction is higher, therefore, the present embodiment carries out Multiple-Scan to same impact point from different directions, obtain the coordinate figure in the ultrasonic scanning space of impact point in each time scanning, for example, as shown in Figure 5, if impact point is in the ultrasonic scanning of twice angled (for example 90 degree), in for the first time scanning, because the thickness direction precision is low, can not accurately obtain thickness direction coordinate figure (namely perpendicular to the coordinate on the scan plane direction), but in for the second time scanning, this direction becomes and is the side direction coordinate, because the precision of side direction is higher, therefore can obtain comparatively accurate coordinate figure.For measurement result repeatedly can be combined, provide a more result of high measurement accuracy, each time need to be measured unification and in a public coordinate system, do projection, and assign weight by correlated measure, recomputate the coordinate figure of this impact point, thereby the axial and lateral error higher with the ultrasonic scanning spatial accuracy remedies the low thickness error of precision, improved the positioning accuracy of impact point.

How the below calculates impact point at the coordinate in reference space with a kind of instantiation explanation, as shown in Figure 5, repeats the same impact point of scanning N time in a plurality of directions, obtains impact point at the coordinate figure X in the i time ultrasonic scanning space _Usi={ X _Usix, X _Usiy, 0,1} ^T(wherein 1≤i≤N), caliberating device 100 obtains position sensor to the transformation matrix T of world coordinates _{W_si}, because position and ultrasound parameter that position sensor is fixed on the probe all do not have variation in scanning process, so the ultrasonic scanning space is to the transformation matrix T in sensor space, position _{S_us}Immobilize.Suppose correlated measure δ _i=[δ _Ix, δ _It, δ _Iz] ^TThe lateral at impact point place when representing the i time ultrasonic scanning (x axle), axial direction (y axle), the correlated measure of thickness direction (z axle).Same δ _N=[δ _Nx, δ _Ny, δ _Nz] ^TWhen representing the N time ultrasonic scanning, the correlated measure of impact point place all directions.Because ultrasound data is at x, y, the precision correlated measure on the z axle (for example error/variance) and the degree of depth, frequency etc. various factors is relevant, δ _iAnd δ _NNot identical.Generally speaking, lateral δ _x, axial direction δ _yLess, thickness direction δ _zLarger.

Different directions has different certainties of measurement, for example axial direction, lateral and thickness direction have different certainties of measurement, give different weights according to correlated measure to scan-data, for example, the component of weight on axial direction, lateral or thickness direction estimated the projected size that makes progress the party according to corresponding scan-data and determined, for the less weight of scan-data distribution of the large direction of correlated measure projection, be that the scan-data of the little direction of correlated measure projection distributes larger weight.

Calculate new coordinate X ' with formula (2) _Usi(coordinate under the i time ultrasonic scanning space (namely with reference to the space)), X ' _UsixBe X ' _Usi=X ' _Usix, X ' _Usiy, X ' _Usiz, 1} ^TThe x component, its computing formula is

X′ _usix＝α _1x·{T _{usi_us1}·X _us1} _x+…α _ix·X _usix+…+α _Nx·{T _{usi_usN}·X _usN} _x----------(4)

0≤α wherein _1x, α _2x... α _Nx≤ 1, $\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_{\mathrm{ix}}=1,$ Order ${\mathrm{\α}}_{1x}=C_x\·\frac{1}{{\{B_1\·{\mathrm{\δ}}_1\}}_x},\·\·\·,{\mathrm{\α}}_{\mathrm{ix}}=C_x\·\frac{1}{{\mathrm{\δ}}_{\mathrm{ix}}},\·\·\·,$ ${\mathrm{\α}}_{\mathrm{Nx}}=C_x\·\frac{1}{{\{B_N\·{\mathrm{\δ}}_N\}}_x},$ Cx makes $\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{\mathrm{\α}}_{\mathrm{ix}}=1$ Normalized parameter, { } _xThe x component of expression vector.

$B_N=\left[\begin{array}{ccc}{r}_{N11}^2& r_{N12}^2& r_{N13}^2\\ r_{N21}^2& r_{N22}^2& r_{N23}^2\\ r_{N31}^2& r_{N12}^2& r_{N33}^2\end{array}\right]$ T _{Usi_usN}Spin matrix $R_N={\left[\begin{array}{ccc}{r}_{N11}& r_{N12}& r_{N13}\\ r_{N21}& r_{N22}& r_{N23}\\ r_{N31}& r_{N12}& r_{N33}\end{array}\right]}_{3*3}$ Square matrix that forms of respective value.

Can get the y axle equally, the new coordinate figure X ' on the z axle _Usiy, X ' _Usiz, obtain at last the coordinate X ' of new rectification _Usi, the X ' of this moment _UsiZ direction of principal axis value X ' _UsizCan be non-vanishing.

X′ _w＝T _{w_si}·T _{s_us}·X′ _usi----------------(5)

T wherein _{S_us}That the ultrasonic scanning space is to the transformation matrix in sensor space, position, T _{W_si}The position sensor space is to the transformation matrix in world coordinates space when being the i time ultrasonic scanning.Through type (4) is with the corrected the i time ultrasonic scanning spatial value X ' of impact point _UsiTransform to the world coordinates space, obtain the world space coordinate X ' of more accurate impact point _wX ' _UsiZ direction of principal axis value X ' _UsizMight be non-vanishing, original two-dimensional ultrasound plane to the conversion between the three-dimensional position sensing device coordinate system, is expanded to certain thickness ultrasonic acoustic beam face to the conversion between the three-dimensional position sensing device space.By the projection of correlated measure, distribute different weights, the axial and lateral error higher with the ultrasonic scanning spatial accuracy remedies the low thickness error of precision, improves the positioning accuracy of impact point.

Object location typical application is the right registration of ultrasonic fusion of imaging mid point in the freedom-arm, three-D ultrasonic system.An important step is the demarcation registration with ultrasonoscopy and another modal data in the ultrasonic fusion of imaging, it be with impact point in world coordinates the position and another modal data in the position of impact point be mapped, the raising of extraterrestrial target spot placement accuracy, can greatly improve registration accuracy, thereby improve the quality of ultrasonic fusion of imaging.The data of another mode can be the imaging datas such as CT, MRI.

In another embodiment, from different directions behind the Multiple-Scan impact point, select a new ultrasonic scanning space that is different from arbitrary scanning direction as the reference space, with all ultrasonic scanning space coordinatess of obtaining behind the Multiple-Scan to this with reference to space projection, obtain each ultrasonic scanning space coordinates to this transformation matrix with reference to the space, correlated measure according to all directions assigns weight for each time scan-data equally, then calculate impact point at this coordinate with reference to the space according to weight and each ultrasonic scanning space coordinates to this transformation matrix with reference to the space, its computing formula is:

X′ _usnew＝α ₁·(T _{usnew_us1}·X _us1)+…+α _i(T _{usnew_usi}·X _usi)++…+α _N·(T _{usnew_usN}·X _usN)---(6)

Wherein: X ' _UsnewThat impact point is at the correction coordinate in reference space, α ₁, α ₂... α _NThe weight vectors of each time scan-data of calculating according to correlated measure, T _{Usnew_usN}That the N time ultrasonic scanning space is to the transformation matrix in this new space, X _UsiThe original coordinates that is impact point in the i time ultrasonic scanning space.

In the above-described embodiments, the correlated measure on the different directions can also be resolution, also can be the ultrasonic distributed data that water listens instrument to measure.Correlated measure can be set-point such as δ _x=1, δ _y=1.5, δ _z=3.Also can be degree of depth l, wavelength X, the isoparametric function of first geometry D that shakes is such as δ _x=f _x(l, λ, D), δ _y=f _y(l, λ, D), δ _z=f _z(l, λ, D), for example δ _x=k _x* l* λ, δ _y=k _y* λ, δ _z=k _z* cos (λ/D), kx wherein, ky, kz be the certainty of measurement on all directions relevant estimate parameter.

In above-described embodiment, the weight of distributing according to correlated measure satisfies

α _Ix≤ 1, α _iCan also be other forms, for example α _iCorrelated measure during for each time scanning impact point, the function alpha of each transformation matrix _Ix=f (δ ₁, δ ₂..., δ _N, T _{Us1_us2}..., T _{Us1_usN}), for example

Perhaps

Deng.

In above-described embodiment, position sensor can be based on the position sensor of electromagnetic induction, also can be based on the position sensor of optical principle, also can be based on other position sensor such as grade of Principles of Acoustics.

Above content is in conjunction with concrete embodiment further description made for the present invention, can not assert that implementation of the present invention is confined to these explanations.For the general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to protection scope of the present invention.

Claims (10)

1. a target point positioning method of a three-dimensional ultrasonic system, characterized in that comprising: Obtain the coordinates of the target point in each ultrasonic scanning space when the ultrasonic probe scans the same target point multiple times from different directions; Selecting an ultrasonic scanning space as a reference space, projecting all the ultrasonic scanning space coordinates obtained after multiple scans to the reference space, and obtaining a transformation matrix from each ultrasonic scanning space coordinate to the reference space; Assign weights to each scan data according to the relevant measures in each direction; Calculate the coordinates of the target point in the reference space according to the weight and the transformation matrix of each ultrasonic scanning space coordinate to the reference space; The coordinates of the target point in the reference space are transformed to the world coordinate space by using the pre-acquired transformation matrix from the ultrasonic scanning space to the world coordinate space. 2. The method of claim 1, wherein the correlation measure is error, variance or resolution. 3. The method according to claim 1 or 2, characterized in that, the following rules are followed when assigning weights to each scan according to the relevant measures in each direction: weights in the axial direction, lateral direction or thickness direction The component is determined according to the projection size of the corresponding scan data measure in this direction, assigning a smaller weight to the scan data in the direction with a large correlation measure projection, and assigning a larger weight to the scan data in a direction with a small correlation measure projection. 4. The method according to any one of claims 1 to 3, wherein the coordinates of the target point in the reference space are calculated using the following formula: ${\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; usref</span>}}^{<span\; class="notranslate">\; \&prime;</span>}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; usref</span>}<span\; class="notranslate">\; \_</span>\mathrm{<span\; class="notranslate">\; usj</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; x</span>}}_{\mathrm{<span\; class="notranslate">\; usj</span>}}<span\; class="notranslate">\; )</span>$ Among them, X′ _usref is the coordinates of the target point in the reference space, N is the number of scans for the same target point, α _j is the weight vector of the jth scan data, _{Tuusref_usj} is the transformation from the jth ultrasonic scan space to the reference space matrix, X _usj is the original coordinates of the target point in the space of the jth ultrasound scan. 5. The method according to claim 4, wherein the reference space is a new space different from the scanning direction; or the reference space is an ultrasonic scanning space of a certain scan in multiple scans. 6. A target point positioning device for a three-dimensional ultrasound system, used to transform the target point from the ultrasonic scanning space to the world coordinate space, characterized in that the device includes: The original coordinate obtaining unit is used to obtain the coordinates of the target point in the ultrasonic scanning space from the ultrasonic image scanned each time when the ultrasonic probe scans the same target point from different directions; The projection unit is used to select an ultrasonic scanning space as a reference space, project all the ultrasonic scanning space coordinates obtained after multiple scans to the reference space, and obtain a transformation matrix from each ultrasonic scanning space coordinate to the reference space; a weight assignment unit, configured to assign weights to each scan data according to the relevant measures in each direction; The coordinate correction unit is used to calculate the coordinates of the target point in the reference space according to the weight and the transformation matrix from the coordinates of each ultrasonic scanning space to the reference space; The coordinate transformation unit is used to transform the coordinates of the target point in the reference space into the world coordinate space by using the pre-acquired transformation matrix from the ultrasonic scanning space to the world coordinate space. 7. The apparatus of claim 6, wherein the correlation measure is error, variance or resolution. 8. The device according to claim 6 or 7, characterized in that, the following rules are followed when assigning weights to each scan according to the relevant measures in each direction: weights in the axial direction, lateral direction or thickness direction The component is determined according to the projection size of the corresponding scan data measure in this direction, assigning a smaller weight to the scan data in the direction with a large correlation measure projection, and assigning a larger weight to the scan data in a direction with a small correlation measure projection. 9. The device according to claim 8, wherein the coordinates of the target point in the reference space are calculated using the following formula: X′ _usref =α ₁ ·(T _{usref_us1} ·X _us1 )+...+α _i (T _{usref_usi} ·X _usi )++...+α _N ·(T _{usref_usN} ·X _usN ) Among them, X′ _usref is the coordinates of the target point in the reference space, α ₁ , α ₂ , ... α _N are the weight vectors of each scan data, Tu _{usref_usN} is the transformation matrix from the Nth ultrasound scan space to the reference space, X _usi is the original coordinates of the target point in the i-th ultrasound space. 10. A three-dimensional ultrasound system, characterized in that, comprising: Ultrasonic probe, used to emit ultrasonic waves to the target part of the examinee; The ultrasonic processing module is used to process the received echo signal and obtain the ultrasonic image of the target site; A calibration device is used to detect the positioning data of the ultrasonic probe, and calibrate the ultrasonic image and the positioning data to obtain a transformation matrix from the ultrasonic scanning space to the world coordinate space; The data calculation module is used to reconstruct or register the calibrated data with other modality data, and output the ultrasonic image and/or data of the target site, and the data calculation module includes the method described in any one of claims 6 to 9. Target point positioning device; The display module is used for displaying the ultrasound image and data of the target site.

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