JP2004202260A - Ultrasonic diagnostic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a three-dimensional image by using information obtained by measuring motion of an ultrasonic probe when performing manual scanning of the ultrasonic probe. <P>SOLUTION: A magnetic field having directionality is generated by a magnetic field generating part, and the magnetic field is detected by a magnetic field detecting part arranged in the ultrasonic probe. Three-dimensional coordinates and an attitude of the ultrasonic probe are detected thereby. A synchronous pulse is generated every time when the ultrasonic probe moves by a prescribed quantity, and the three-dimensional image is constituted by using echo data on a scanning surface taken in at that time. In this case, a scanning method determining part 76 determines a scanning method (moving scanning and rotary scanning) of the ultrasonic probe, and the three-dimensional image corresponding to the determined scanning method is constituted. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to an ultrasonic diagnostic apparatus in which an ultrasonic probe is manually scanned.

  In a two-dimensional tomographic image display (so-called B-mode display) in a conventional ultrasonic diagnostic apparatus, a cross section in a living body is displayed as a black and white gray image. However, since only the cut surface of the tissue to be observed is expressed, it is difficult to three-dimensionally recognize and grasp the tissue on the image. On the other hand, devices that transmit and receive ultrasonic waves to and from a three-dimensional region in a living body to form a three-dimensional image of a tissue are being put into practical use. The three-dimensional image is obtained by, for example, performing shading to give a sense of depth to the tissue surface obtained by performing surface extraction, and can express the tissue three-dimensionally. In addition, as a method of imaging a three-dimensional region, an integration method, a projection method, and the like are also known, but an image obtained by such a method is planar and has no sense of depth.

  In the above-described conventional three-dimensional image processing, all of the echo data captured in the three-dimensional area is temporarily stored in a three-dimensional echo data memory, and thereafter, each echo data is reconfigured by software processing or the like. There is a need. Therefore, it takes a lot of time to perform a calculation for obtaining one three-dimensional image, and it is extremely difficult to display a three-dimensional image in real time. Further, since the conventional three-dimensional image is basically based on shading of the surface, it has basically been impossible to spatially express the inside of the tissue through the tissue.

  Therefore, the applicant of the present application has proposed a new image processing method in Japanese Patent Application No. 8-185781. Although the principle will be described in detail later, according to such an image processing method, the tissue can be expressed three-dimensionally or transparently, and according to the user's preference, the three-dimensional expression of the tissue surface can be emphasized or the internal tissue can be expressed. Can be emphasized.

  In this image processing method, a voxel operation (described later) is sequentially performed in a time-series order of the received signal, that is, for each piece of echo data existing along the ultrasonic beam. Is executed until a predetermined termination condition is satisfied. Then, the voxel operation value at the time of the end is associated with the pixel value. Therefore, if the end condition is appropriately set, the voxel operation is terminated near the tissue surface, and a display in which the tissue expression is emphasized can be performed. In addition, there are the following known documents.

JP-A-55-116342 JP-A-6-14923 JP-A-62-68442

  However, conventionally, in order to form a three-dimensional image based on the voxel operation or another three-dimensional image, it is necessary to use a dedicated ultrasonic probe for capturing three-dimensional data. This ultrasonic probe includes, for example, an array transducer that is electronically scanned inside the probe, and a scanning mechanism that mechanically scans the array transducer in a direction orthogonal to a scanning plane. It is heavier and larger than an acoustic probe. Therefore, operability is reduced.

  Conventionally, various ultrasonic probes are prepared according to each diagnosis site. Similarly, in order to form a three-dimensional ultrasonic image of each diagnostic site, it is necessary to prepare a dedicated three-dimensional data acquisition ultrasonic probe for each diagnostic site. However, this is disadvantageous in terms of cost. In other words, it is desired to be able to perform three-dimensional ultrasonic diagnosis using the existing ultrasonic probe as it is or by only slightly improving the existing ultrasonic probe.

  By the way, a moving amount detector such as a roller is attached to the electronic scanning ultrasonic probe, the position is measured at the time of manual scanning of the ultrasonic probe, and a three-dimensional image is constructed using the measurement result. It is also possible to do. However, when the contact state of the ultrasonic probe with the surface of the living body is not good, the position cannot be detected with high accuracy. Therefore, it is desired to measure the motion (position and orientation) of the ultrasonic probe without contact, without using such contact-type position detection.

  Further, if the scanning method of the ultrasonic probe is different, the operating conditions of the apparatus, particularly the conditions of image processing, are different correspondingly, but conventionally, an ultrasonic diagnostic apparatus capable of automatically determining the scanning method has been provided. Not.

  An object of the present invention is to realize appropriate control according to a scanning method of manual scanning. Another object of the present invention is to ensure that proper image processing is performed.

(1) In a desirable mode, the ultrasonic diagnostic apparatus measures a portable ultrasonic probe that forms a scanning surface by electronically scanning an ultrasonic beam, and a movement of the ultrasonic probe by manual scanning. Motion measuring means, a timing signal generating means for sequentially generating a capture timing signal for each predetermined amount of motion of the ultrasonic probe, and echo data of each scanning plane synchronized with the capture timing signal. Image processing means for forming an ultrasonic image obtained by imaging a three-dimensional region in the sample.

  According to the above configuration, when the ultrasonic probe is manually scanned, the motion (parallel motion, rotational motion, and the like) of the ultrasonic probe is measured, and a capture timing signal is sequentially generated based on the measurement result. . Then, the echo data of the scanning plane specified by the capture timing signal is used in image processing. Here, the electronic scanning of the ultrasonic beam can be periodically and repeatedly executed. Even in such a case, only necessary data can be extracted in synchronization with the capture timing signal. Of course, the data may be fetched by causing the electronic scanning to be performed once or several times when the fetch timing signal is generated.

  As described above, since the echo data can be extracted in units of scanning planes, the present invention is particularly advantageous when performing three-dimensional image processing in units of scanning planes.

  In a preferred aspect, the motion measuring means includes a magnetic field generator arranged near the subject, a magnetic field detector arranged on the ultrasonic probe, and an output signal from the magnetic field detector. Calculating means for calculating the motion of the ultrasonic probe based on the calculated value.

  According to the above configuration, a steady magnetic field or a fluctuating magnetic field is formed around the subject, and the magnetic field is detected by the magnetic field detector arranged on the ultrasonic probe. Then, based on the detection result, the motion of the ultrasonic probe, that is, its three-dimensional position and orientation (posture) are calculated. Since the magnetic field is used, it is not affected by the transmission and reception of ultrasonic waves by the ultrasonic probe. It is desirable to set and measure a plurality of magnetic fields having different directions according to the number of measurement dimensions of the movement. For example, when measuring three-dimensional coordinates and a rotation angle on each coordinate axis, for example, three magnetic field generating coils and three magnetic field detecting coils having different directions are used.

  In order to detect the magnetic field with high accuracy, it is desirable to remove the magnetic member from the magnetic field generator and the magnetic field detector as much as possible. Note that, contrary to the above configuration, a magnetic field generator may be provided on the ultrasonic probe, and the magnetic field detector may be fixedly arranged. However, when comparing the magnetic field generator with the magnetic field detector, the magnetic field detector is generally smaller and lighter, and it is desirable to provide it in the ultrasonic probe.

  In a preferred aspect, the apparatus includes a detachable member for attaching and detaching the magnetic field detector to and from the ultrasonic probe. As described above, if the magnetic field detector is made detachable, an existing ultrasonic probe can be used as an ultrasonic probe for capturing three-dimensional data, and a dedicated probe is not required.

  In a preferred aspect, the magnetic field detector is built in the ultrasonic probe. Placing a magnetic field detector outside the ultrasonic probe may reduce the operability of the probe, but providing a magnetic field detector inside the probe can solve the problem . In this case, it is desirable that a part or the whole of the probe case is made of, for example, a non-magnetic material.

  In a preferred aspect, an appropriate range setting means for setting an appropriate range related to the motion of the ultrasonic probe, and a process of restricting the image processing if the motion of the ultrasonic probe is outside the appropriate range. And limiting means.

  According to the above configuration, for example, when the ultrasonic probe is separated from the body surface or when the ultrasonic probe falls by mistake, execution of image processing can be limited. That is, as a result, the suitability of the manual scanning can be determined.

  In a preferred aspect, the appropriate range is set with respect to at least one piece of motion information among three-dimensional coordinates, a moving speed, a rotation angle, and a rotation angular speed of the ultrasonic probe.

  In a preferred aspect, the apparatus further includes a scanning mode determination unit configured to determine a scanning mode of the ultrasonic probe based on the motion measurement result, and control corresponding to the scanning mode is performed. If the scanning method can be automatically detected, for example, even if different scanning is performed between the first manual scanning and the second manual scanning, a complicated operation such as a change input of a scanning condition by a user is eliminated. In addition, appropriate image processing can always be expected.

  In a preferred aspect, the scanning method determination unit determines moving scanning and rotating scanning, and an ultrasonic image corresponding to each scanning method is formed.

(2) Preferably, the image processing means sequentially executes a predetermined voxel operation on the echo data along each ultrasonic beam, thereby calculating a pixel value of each pixel constituting the ultrasonic image. Including means.

Further, in a preferred embodiment, the voxel calculation means calculates the opacity calculating means for calculating the opacity alpha _i voxel i based on the echo data e _i, the transparency of beta _i voxel i based on the echo data e _i A transparency calculating means, a light emitting amount calculating means for multiplying the echo data value e _i by an opacity α _i to calculate a light emitting amount of the voxel i, and a transparency β of the voxel i to the output light quantity of the immediately preceding voxel i-1 _i , a transmitted light quantity calculating means for calculating the transmitted light quantity of the voxel i, and a light quantity adding means for adding the emitted light quantity and the transmitted light quantity to obtain an output light quantity of the voxel i. The stereoscopic projection image is formed by making the light amount correspond to the pixel value.

Further, in a preferred embodiment, the voxel calculation means, and opacity calculating means for calculating the opacity alpha _i voxel i based on the echo data ei, the echo data e _i, the opacity alpha _i and one Output light quantity calculating means for calculating the output light quantity C _OUTi of the voxel i based on the input light quantity C _INi corresponding to the output light quantity of the previous voxel i-1, and making the output light quantity of the end voxel correspond to the pixel value. To form the three-dimensional projected image.

  According to the above configuration, voxel processing using opacity or the like is performed along the ultrasonic beam. As a result, it is possible to sequentially process the sequentially acquired echo data in chronological order and to eliminate the need for the three-dimensional data memory required in the conventional device. That is, the captured echo data is processed in the capturing order, and the data processing can be sufficiently performed without storing all the echo data once in the three-dimensional data memory.

Incidentally, the opacity α _i relates to the degree of diffusion and scattering of the ultrasonic wave to the surroundings of the voxel i, and the light emission amount seems to indicate the intensity of the voxel i as a sound source (light source). On the other hand, the transparency β _i relates to the transmittance of ultrasonic waves, and the amount of transmitted light is considered to correspond to the transmittance when voxel i is viewed as a transmission medium. The light emission amount and the transmitted light amount are added to calculate the output light amount of the voxel i. Here, the output light quantity indicates the degree of contribution of the voxel i to the pixel value. This output light amount is transferred to the next voxel voxel processing (calculation of transmitted light amount). Then, when the voxel processing reaches the final voxel, the output light amount of the final voxel is converted into a pixel value. Then, when each pixel value is obtained, one stereoscopic projection image is formed as a set of those pixel values.

  It has been confirmed by experiments that this ultrasonic image has both the characteristics as a projection image and the characteristics as a stereoscopic image. That is, a tissue in a living body can be expressed in a transparent manner like an X-ray photograph, while it can be expressed with a sense of depth like an ultrasonic three-dimensional image. Therefore, for example, the surface and the inside of a fetus can be imaged by the same processing, and three-dimensional grasp of a tissue can be easily performed in disease diagnosis.

  Of course, by changing the definitions of the opacity and the transparency, an ultrasonic image having a desired image quality can be formed. For example, it is possible to enhance the transparency or the three-dimensional effect. Alternatively, the tissue surface can be enhanced or the interior of the tissue can be enhanced.

Such adjustment is performed by changing the definition of the opacity and the like, and more specifically, can be performed by appropriately setting an end condition using the opacity as a parameter. In this case, if the value of each opacity α _i to be sequentially added is large, the processing ends at a relatively early stage. For example, the image expression ends by seeing through to the surface of the tissue. Conversely, if the value of each opacity α _i is small, the processing ends at a relatively late stage. For example, the image processing ends by seeing deep inside the tissue.

(3) An ultrasonic diagnostic apparatus according to the present invention is based on a portable ultrasonic probe, motion measuring means for measuring motion of the ultrasonic probe by manual scanning, and a measurement result of the motion. It is characterized by including a scanning method determining means for determining a scanning method, and a control unit for executing control based on the determined scanning method.

  In a preferred aspect of the present invention, the control unit executes control for forming an ultrasonic image corresponding to a scanning method.

  In a preferred aspect of the present invention, the motion measuring means includes a magnetic field generator and a magnetic field detector, one of which is fixedly disposed near the subject, and the other of which is disposed on the ultrasonic probe. It is characterized by being performed.

  Preferably, the scanning method determining means determines whether the scanning is moving scanning or rotating scanning. Preferably, the scanning method determination unit determines the manual scanning method based on movement information and rotation information as a measurement result of the movement. Preferably, the scanning method determination unit calculates a difference between a current value and a previous value of each of the movement information and the rotation information, and determines the manual scanning method based on the difference value. Desirably, the scanning method determination unit outputs an error signal when an appropriate image cannot be constructed. Preferably, the scanning method determination unit outputs an error signal when a composite scan including a translation scan and a rotation scan is performed.

  As described above, according to the present invention, appropriate processing can be realized according to the scanning method of manual scanning. According to the present invention, appropriate image processing can be performed.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

  First, prior to the description of the device configuration, the principle of image processing according to the embodiment will be described.

[Explanation of image forming principle]
The image processing method according to the present embodiment is based on a known volume rendering (Volume Rendering) method, and is an extension of the method to real-time image processing (particularly, ultrasonic image processing). At that time, special conditions are taken into account.

  As shown in FIG. 1A, when an ultrasonic beam directed in the Y direction is scanned in the X direction, a scanning surface 10 is formed. When the scanning surface 10 is moved in the Z direction, a three-dimensional echo data capturing space 12 is formed as is well known. The three-dimensional echo data capture space 12 is subjected to voxel processing according to the present embodiment along each ultrasonic beam to project the three-dimensional echo data capture space 12 on the projection plane 16 as shown in FIG. It is the ultrasonic image 100 of B). In the ultrasonic image 100, one line 100a in the X direction corresponds to one scanning plane 10. In other words, one ultrasonic beam (perspective line) corresponds to one pixel in the ultrasonic image 100.

  Here, since the voxel processing described in detail below is performed on the acquired echo data in the time series order of the echo data, each echo data is temporarily stored in the three-dimensional echo data memory, and is necessary for image formation. There is no need to read out echo data in order, and data processing synchronized with data capture is possible.

Now, the concept of the voxel 20 is shown in FIGS. 2 and 3. One voxel corresponds to one echo data obtained by A / D conversion of a received signal, in other words, one voxel corresponds to a volume (sample point) corresponding to one cycle of the A / D conversion rate. It is. That is, the ultrasound beam is assumed to be an aggregate of many voxels. FIG. 2 shows each voxel from i-1 to _LLAST . The value obtained by performing the processing sequentially from the first voxel corresponds to the luminance value P (x, y) of one pixel constituting the ultrasonic image.

Here, opacity α and transparency β (β = (1−α) in the present embodiment) are defined for each voxel. The opacity α corresponds to spontaneous light emission around the voxel as shown in FIG. The transparency (1−α) corresponds to the degree of transmission of light from the previous voxel in the voxel. The opacity α is set in a range of 0 ≦ α ≦ 1, and in the present embodiment, the opacity is defined as a function of the echo data (echo value). Specifically, for example,
[Equation 1]
α = k1 ・ e ^k2・ ・ ・ (1)
Is defined as Here, e is the value of the echo data, and k1 is a coefficient (parameter), which is variably set by the user. Preferably, a numerical value larger than 1 is substituted for k2, for example, k2 = 2 or 3. That is, α changes nonlinearly with respect to the value e of the echo data.

As shown in FIG. 2, for a certain voxel i, an input light amount C _INi and an output light amount C _OUTi are defined, and the input light amount C _INi is set to the output light amount C _OUTi-1 of the _immediately preceding voxel i _-1 . equal. That is,
[Equation 2]
C _INi = C _OUTi-1 (2)
There is a relationship. However, C _INi = 0 at the start voxel at which the voxel processing is started. Note that the start voxel is set automatically or artificially.

For each voxel, a light emission amount and a transmission light amount are defined based on the opacity α and the transparency (1−α). That is, the light emission amount of voxel i is defined as the product of the opacity and the echo data, and is α _i · e _i . The transmitted light amount of the voxel i is defined as the product of the transparency and the input light amount, and is (1−α _i ) · C _INi .

In the present embodiment, as shown in FIG. 4, the light emission amount and the transmitted light amount are added as follows, and the output light amount C _{OUTi of the} voxel is determined.
[Equation 3]
C _OUTi = (1−α _i ) · C _INi + α _i · e _i (3)

However, C _INi = C _OUTi−1 from the above second equation. That is, the calculation result of the previous voxel is used for calculation of the next voxel.

While the above equation (3) is sequentially performed from the starting voxel to the next voxel and then to the next voxel, the opacity α _i of each voxel is added, and the added value Σα _i reaches 1. At this point, the process is terminated (termination condition). However, even when the processing is the last (or the set depth) voxel L _LAST , the processing is terminated (forced termination condition). In other words, the conditions under which the processing ends
[Equation 4]
Σα _i = 1 or i = L _LAST (4)
It is. The termination of the processing when Σα _i = 1 means that the processing is stopped when the sum of the opacity reaches 1, and of course, depending on the conditions, the condition of the above formula 4, especially the maximum addition of α _i The value (end determination value) may be changed.

The output light amount C _OUT of the voxel (final voxel) at the time when the above-described end determination is made is used as the luminance P (x, y) of the corresponding pixel. Then, when such a pixel value calculation for each ultrasonic beam is performed for all the ultrasonic beams, the pixel values of all the pixels constituting the ultrasonic image can be obtained. That is, one ultrasonic image is formed.

  As indicated by the above-described third expression, the values of all the echo data from the start voxel to the end voxel are reflected in the luminance value P (x, y) of the pixel. However, it reflects not only simple integration as in the past, but also both scattering and absorption of ultrasonic waves at each voxel. Therefore, it is possible to generate an ultrasonic image having both a sense of depth (three-dimensional effect) and a sense of transparency, such as an image formed by light transmitted from a light source and scattered and absorbed by each voxel. Can be configured.

By the way, in the above third equation, the transparency is defined by (1−α _i ), that is, the transparency can be represented by the opacity α _i , so that the concept of transparency can be apparently deleted from the arithmetic expression. . Therefore, the output light amount C _OUTi can be calculated based on the same principle by _modifying the third expression as follows.
[Equation 5]
C _OUTi = (1−α _i ) · C _INi + α _i · e _i (3)
= C _INi + α _i · (e _i -C _INi ) (5-1)
= C _INi + Δ _i (5-2)
(Where Δ _i = α _i · (e _i −C _INi ))

5-1 Expression of the intended rewriting the third equation, replacing the second term in delta _i, 5-2 equation is obtained. That is, the output light amount C _OUTi of the voxels i may be defined as the sum of the corrected amount delta _i to the input light quantity C _INi. As is clear from the above equation deformation process, the concept of transparency (1−α _i ) is also included in this equation 5-2, and there is no difference in principle.

[Preferred Embodiment]
FIG. 5 shows a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention, and FIG. 5 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus.

  The ultrasonic probe 30 is, for example, an ultrasonic probe used in contact with a body surface. Of course, the present invention can be applied to an ultrasonic probe inserted into a body cavity, for example. The ultrasonic probe 30 has a built-in array transducer in which a plurality of transducers are arranged and arranged. The array transducer is electronically scanned under the control of the ultrasonic transmission / reception unit 44, whereby the ultrasonic beam is scanned to form a scanning surface. This is similar to a conventional ultrasonic probe. The ultrasonic probe 30 is connected to the apparatus main body by a probe cable (not shown).

  In the ultrasonic diagnostic apparatus according to the present embodiment, a movement measuring unit 32 that measures the position and orientation of the ultrasonic probe 30 is provided. In the present embodiment, the motion measuring unit 32 includes a magnetic field generating unit 34, a magnetic field detecting unit 36 for detecting a generated magnetic field, and a motion detecting unit 38 for calculating motion information based on the detection result. Is what is done. In addition, as the magnetic field generation unit 34, the magnetic field detection unit 36, and the motion detection unit 38 illustrated in FIG. 5, known ones can be used. The magnetic field generating unit 34 is disposed, for example, on a bed on which a subject is placed, and is configured by, for example, three magnetic field generating coils that generate a magnetic field in each of the X, Y, and Z directions. The magnetic field generator 34 is supplied with a predetermined magnetic field generation drive signal from the motion detector 38. The magnetic field generator 34 forms a fluctuating magnetic field having components in each direction.

  The magnetic field detection unit 36 is, for example, a cube having a side of about 1 cm, and detects a magnetic field generated by the magnetic field generation unit 34. The magnetic field detection unit 36 includes, for example, three mutually orthogonal magnetic field detection coils for detecting a magnetic field in each direction. The detection signal detected by each coil is output to the motion detection unit 38. In the present embodiment, the magnetic field detection unit 36 is detachably attached to the ultrasonic probe 30. For example, the magnetic field detection unit 36 is mounted on the ultrasonic probe 30 by a mounting belt described later. Of course, as described later, the magnetic field generator 34 may be built in the ultrasonic probe 30.

  When the magnetic field generator 34 and the magnetic field detector 36 are compared in terms of morphology, the magnetic field detector 36 is generally much smaller. Therefore, in the present embodiment, the magnetic field detection unit 36 is provided in the ultrasonic probe 30. However, the magnetic field generator 34 may be attached to the ultrasonic probe 30 while the magnetic field detector 36 is fixedly arranged on a bed, for example. In principle, even with such a configuration, the motion of the ultrasonic probe 30 can be detected.

  FIG. 6 shows a specific example regarding the arrangement of the magnetic field generation unit 34 and the magnetic field detection unit 36. In FIG. 6, a subject 200 is placed on a bed 201. A magnetic field generator 34 is fixedly arranged below the bed 201. Thereby, a magnetic field 202 is formed. Incidentally, the magnetic field 202 is a steady magnetic field or a fluctuating magnetic field.

  The magnetic field detector 36 is attached to the ultrasonic probe 30 by the attachment belt 64. Specifically, the magnetic field detecting unit 36 is fixed to the mounting belt 64, and by attaching the mounting belt 64 to the ultrasonic probe 30, as a result, the magnetic field detecting unit 36 is mounted on the ultrasonic probe 30. You. According to such a mounting belt 64, there is an advantage that the magnetic field detecting unit 36 can be mounted on the ultrasonic probes 30 of various sizes. Of course, the magnetic field detection unit 36 may be attached to the ultrasonic probe 30 using, for example, a double-sided tape or an engagement mechanism.

  The signal line 62 extending from the magnetic field detection unit 36 is led to the apparatus main body together with the cable 60 coming out of the ultrasonic probe 30, for example. In this case, it is desirable to perform clipping or the like at predetermined intervals in order to integrate the cable 60 and the signal line 62.

  In the measurement environment as shown in FIG. 6, when performing an ultrasonic diagnosis of, for example, the abdomen of the subject 200, the ultrasonic probe 30 is gripped by the operator, and in that state, for example, the ultrasonic probe The ultrasonic probe 30 is manually moved and scanned in a direction orthogonal to a scanning plane formed by the scanning direction 30, that is, in a manual scanning direction 204. Thus, a three-dimensional data acquisition space can be constructed in the subject 200.

  In the example illustrated in FIG. 6, the magnetic field generating unit 34 is fixed to the back side of the bed 201. However, the magnetic field generating unit 34 is not necessarily fixed to the bed 201, for example, beside a subject on the bed, a wall near the subject, or the like. May be provided.

  Returning to FIG. 5, the ultrasonic transmission / reception unit 44 supplies a transmission signal to the ultrasonic probe 30 as in the related art, and performs predetermined signal processing on a reception signal from the ultrasonic probe 30. To do. The ultrasonic transmission / reception unit 44 controls the electronic scanning of the ultrasonic beam. The received signal (echo data) output from the ultrasonic transmission / reception unit 44 is output to the next data selection unit 46.

The motion detecting unit 38 in the motion measuring unit 32 determines the three-dimensional coordinates X, Y, and Z of the ultrasonic probe 30 and the coordinate axes of the ultrasonic probe 30 based on the output signal from the magnetic field detecting unit 36. The rotation angles θ _X , θ _Y , and θ _Z are output. Incidentally, if the manual scanning is always performed by the parallel movement, the information on the rotation angle is not necessarily required. If the ultrasonic probe 30 moves substantially within the XY plane, information in the Z direction is not required.

  The timing control unit 40 determines the timing for specifying the scan plane from which the echo data is to be acquired, based on various types of motion information output from the motion detection unit 38. The specific configuration is shown in FIG. 7, which will be described later in detail.

  The pulse generation unit 42 outputs a synchronization pulse (data acquisition signal) 206 having a predetermined level based on the timing signal output from the timing control unit 40. The synchronization pulse 206 is output to the data selection unit 46 and the image construction unit 52 described later.

  The data selector 46 has a function of selecting and outputting only the echo data of the specified scanning plane at the timing when the synchronization pulse 206 is obtained. That is, in the present embodiment, electronic scanning of the ultrasonic beam is always performed in the ultrasonic probe 30 under the control of the ultrasonic transmitting and receiving unit 44. As a result, some echo data is always output from the ultrasonic transmitting and receiving unit 44. However, the data selector 46 extracts only the necessary echo data within the scanning plane from such data. As a result, it is possible to extract echo data in units of scanning planes. Note that the synchronization pulse 206 may be given to the ultrasonic transmission / reception unit 44 so that electronic scanning is performed at that timing to acquire echo data. In this case, the output of the synchronization pulse itself corresponds to the selection of the echo data.

  The three-dimensional projection image forming unit 48 includes a voxel calculation unit 50 and an image construction unit 52, and performs three-dimensional projection based on the above-described image processing principle (especially, equations (3) and (4)). An image is formed. The voxel calculation unit 50 executes the above-described voxel calculation for each piece of echo data along the ultrasonic beam, and determines a pixel value of a pixel corresponding to the ultrasonic beam. The opacity parameter used in the voxel calculation is set by the opacity setting unit 56. The range of the voxel operation, that is, the operation end point, is set by the operation range setting unit 54. The pixel values corresponding to each ultrasonic beam output from the voxel operation unit 50 are sent to the image forming unit 52, where a three-dimensional projected image for one screen is formed. At the same time, the brightness of each pixel value is converted and output as image data to the display unit 58.

  As shown in FIG. 1, in the image processing according to the present embodiment, one line of image data is formed for one scanning plane, in other words, the image processing is performed in units of scanning planes. . In response to this, the data selector 46 extracts echo data for each scanning plane in synchronization with the synchronization pulse.

  Therefore, according to the present embodiment, it is not necessary to perform a complicated process of temporarily storing all the echo data in the three-dimensional echo data memory and then reconstructing the data while considering the three-dimensional coordinates as in the related art. , Only necessary data can be sequentially processed in the time series order. In the case where the manual scanning is performed quickly, one stereoscopic projection image is formed early as a result, and when the manual scanning is slow, one stereoscopic projection image is formed at a speed corresponding thereto. Will be done.

  Next, a specific configuration of the timing control unit will be described with reference to FIG.

7, the exercise information input unit 70 receives the respective exercise information output from the exercise detection unit 38 shown in FIG. If the operation of resetting the origin is performed immediately before the manual scanning of the ultrasonic probe is started, the position and orientation of the ultrasonic probe 30 at that time are set as the origin. As a result, the origin of a virtual scale described later is also determined. The motion information of the ultrasonic probe 30 after the origin is reset is output after being divided into movement information and rotation information. Here, the movement information is an X coordinate, a Y coordinate, and a Z coordinate, and the rotation information is angle information of θ _X , θ _Y , and θ _Z.

  The processing restricting unit 72 executes a control for interrupting the image processing when each exercise information does not fall within the proper range set by the proper range setting unit 74. For example, when the ultrasonic probe falls from the hand or when the operator separates the ultrasonic probe from the subject, the echo data in that state is excluded from image processing in order to eliminate such echo data. There are restrictions on image processing. Here, the exercise information to be managed includes, for example, a moving speed, a rotational angular speed, and the like, in addition to the input information (three-dimensional coordinates, rotation angle). By controlling the speed, an alarm can be issued to the operator when, for example, manual scanning is extremely fast and image processing cannot be performed properly. For this reason, when the processing restriction unit 72 determines that the value is outside the appropriate range, an alarm is output to a control unit (not shown).

  If the processing restriction unit 72 determines that the movement is within the appropriate range, the movement information and the rotation information output from the movement information input unit 70 are output to the scanning method determination unit 76. In the present embodiment, the scanning method determination unit 76 determines whether the manual scanning is a moving scan (parallel movement scanning) or a rotational scanning. Specifically, the difference between the current value and the immediately preceding value is calculated for each piece of exercise information, and the scanning method is determined by referring to the difference values. For example, when the difference value is large with respect to the movement information, it is determined that the scanning is parallel movement scanning, and when the difference value is large with respect to the rotation information, it is determined that the scanning is rotation scanning. In this case, if a composite scan in which the rotational movement is performed while performing the parallel movement is performed, an error signal is output to a control unit (not shown) because an appropriate image may not be constructed. . In the present embodiment, the scanning method is determined using the difference of the motion information. However, for example, the scanning method may be determined by calculating an integrated value or a three-dimensional vector.

When the scanning method determination unit 76 determines that the scanning is parallel movement scanning, the movement information is sent to the movement vector calculation unit 80. The movement vector calculation unit 80 calculates a movement direction vector V _XYZ relating to the movement of the ultrasonic probe by calculating the difference between the current three-dimensional coordinate value and the immediately preceding three-dimensional coordinate value. However, in the present embodiment, the calculation of the vector is executed only between two pieces of motion information obtained first after the origin is reset, and thereafter, the calculation of the movement direction vector is omitted. Of course, the moving direction vector may always be calculated, and the calculation result may be used for image processing.

When the moving direction vector V _XYZ is obtained as described above, a virtual scale 210 is assumed in a three-dimensional space as shown in FIG. That is, the direction of the virtual scale 210 is oriented in the direction of the movement direction vector, and the origin of the virtual scale 210 is the position of the ultrasonic probe at the time when the origin is reset.

  The interval setting unit 84 sets the output interval of the timing signal based on the transmission / reception conditions, and conceptually sets the interval of the scales on the virtual scale 210. Here, the scale corresponds to the output position of the timing signal.

  The moving position comparing unit 82 compares the current position of the ultrasonic probe with the scale assigned on the virtual scale 210 based on the moving information output via the scanning method determining unit 76, and When the probe matches the scale or passes through the scale, the timing generator 86 is instructed to generate a timing signal. When the generation instruction is input, the timing generator 86 outputs a timing signal to the pulse generator 42 shown in FIG.

  Therefore, regardless of the moving speed of the ultrasonic probe 30, the synchronization pulse 206 is generated every time the ultrasonic probe 30 moves at a constant interval from the origin, and the output of the synchronization pulse 206 is The echo data in the scanning plane which are taken in synchronously are sequentially image-processed.

In FIG. 7, when the scanning method determination unit 76 determines that the scanning is the rotation scanning, the rotation vector calculation unit 88 calculates the rotation direction vector Vθ _XYZ based on the rotation information. In the present embodiment, the calculation of the rotation direction vector is performed only once after the origin is reset. However, the calculation of the rotation direction vector may be always performed thereafter.

  Based on the rotation direction vector thus calculated, a circular virtual scale 212 can be assumed as shown in FIG. The interval setting unit 92 assigns the scales on the circular scale 212 shown in FIG. 9 based on the transmission and reception conditions. When the current rotation angle of the ultrasonic probe 30 matches the scale on the virtual scale 212 or passes through the scale, the rotation angle comparison unit 90 compares the rotation angle with the timing generation unit 86. The generation instruction is output from the unit 90. As a result, the timing signal is output from the timing generator 86 to the pulse generator 42. The rotation vector calculation unit 88 calculates the rotation direction vector by calculating the difference between the current rotation information and the previous rotation information.

  FIG. 10 shows the relationship between the moving scan of the ultrasonic probe 30 and the ultrasonic image formed thereby. Each time the ultrasonic probe 30 passes through the scale on the virtual scale 210, echo data is fetched for each scan plane, and in synchronization with this, image data processing is executed for each scan plane. Specifically, an image 10A for one line is formed for one scanning surface. Therefore, by performing the moving scanning operation over a predetermined range, one ultrasonic image, that is, a three-dimensional projected image can be formed. The virtual scale 210 in the moving scan corresponds to the coordinates in a predetermined direction in the ultrasonic image, and if the scale on the virtual scale is made finer, the pixel density in the direction in the ultrasonic image is also improved. If necessary, interpolation or averaging between image data may be executed.

  FIG. 10 shows the processing in the case where the ultrasonic probe 30 performs parallel movement scanning. However, the same processing as described above is executed also in the case where the ultrasonic probe is rotationally scanned. That is, each time the ultrasonic probe 30 rotates by a predetermined angle, an image of one line in a predetermined direction in the ultrasonic image is formed. That is, radial scanning is performed.

  Next, another embodiment will be described.

  In the above embodiment, the synchronization pulse is generated by making the virtual scale coincide with the moving direction of the ultrasonic probe 30. For example, as shown in FIG. Two orthogonal virtual scales, that is, a main axis virtual scale 300 and a sub axis virtual scale 302, may be set in a plane including the virtual scale, and image processing may be performed using these virtual scales. In this case, for example, every time the ultrasonic probe 30 crosses the scale of the virtual spindle scale 300, a spindle synchronization pulse 304 is generated, and the spindle synchronization pulse 304 is output to the data selector 46 shown in FIG. At the same time, every time the ultrasonic probe 30 crosses the scale on the sub-axis virtual scale 302, a sub-axis synchronization pulse 306 is generated, and the generated pulse is used as the coordinates of the ultrasonic probe 30 in the direction of the sub-axis virtual scale 302. You may output to the structure part 52.

  FIG. 12 shows such a process. When the ultrasonic probe 30 moves in a diagonal direction, an image 10A for one line corresponding to the scanning plane is sequentially displayed in a diagonal direction. become. That is, an image is constructed with the same image as the oblique scanning.

  In the above-described embodiment, the magnetic field detection unit 36 is mounted on the outer surface of the ultrasonic probe 30. However, for example, as shown in FIG. The unit 36 may be provided. An array vibrator 406 including a plurality of vibrating elements is built in the main body case 402 of the probe, and a cable group 406A extending from each vibrating element is drawn into the probe cable 404. Similarly, it is desirable that the signal line group 36 </ b> A extending from the magnetic field detection unit 36 be drawn into the probe cable 404.

  According to the above-described embodiment, there is an advantage that three-dimensional echo data can be easily captured using an existing ultrasonic probe or the like without impairing the advantage of the voxel operation.

FIG. 3 is a diagram illustrating a relationship between a three-dimensional data capturing space and a projected image. FIG. 4 is a diagram illustrating a relationship between an input light amount and an output light amount of each voxel. It is a figure which shows the light emission amount of each voxel. FIG. 6 is a diagram for explaining the output light amount of a voxel. FIG. 1 is a block diagram illustrating an overall configuration of an ultrasonic diagnostic apparatus according to the present invention. It is a schematic diagram which shows the specific example of a magnetic field generation part and a magnetic field detection part. FIG. 3 is a block diagram illustrating a specific configuration of a timing control unit. FIG. 7 is a diagram illustrating a relationship between a virtual scale of a straight line and a synchronization pulse. FIG. 7 is a diagram illustrating a relationship between a circular virtual scale and a synchronization pulse. FIG. 4 is a diagram illustrating image formation by parallel movement scanning. FIG. 4 is a diagram illustrating two orthogonal virtual scales. FIG. 5 is a diagram illustrating image formation by two orthogonal virtual scales. It is a figure showing other embodiments of an ultrasonic probe.

Explanation of reference numerals

  30 ultrasonic probe, 32 motion measuring section, 34 magnetic field generating section, 36 magnetic field detecting section, 38 motion detecting section, 40 timing control section, 42 pulse generating section, 46 data selecting section, 48 stereoscopic projection image forming section, 50 Voxel operation unit, 52 Image composition unit.

Claims (8)

A portable ultrasonic probe,
Motion measuring means for measuring the motion of the ultrasonic probe by manual scanning,
Scanning method determining means for determining a manual scanning method based on the measurement result of the movement,
A control unit that performs control based on the determined manual scanning method,
An ultrasonic diagnostic apparatus comprising: The device of claim 1,
The ultrasonic diagnostic apparatus, wherein the control unit executes control for forming an ultrasonic image corresponding to the manual scanning method. The device according to claim 1 or 2,
The motion measuring means includes a magnetic field generator and a magnetic field detector, one of which is fixedly arranged in the vicinity of the subject, and the other of which is arranged on the ultrasonic probe. Ultrasound diagnostic device. The device of claim 1,
An ultrasonic diagnostic apparatus according to claim 1, wherein said scanning method determination means determines translation scanning or rotation scanning. The device of claim 1,
The ultrasonic diagnostic apparatus according to claim 1, wherein the scanning method determining means determines the manual scanning method based on translation information and rotation information as a result of the movement measurement. The device according to claim 5,
The scanning method determining means calculates a difference between a current value and a previous value for each of the translation information and the rotation information, and determines the manual scanning method based on the difference value. Ultrasound diagnostic device. The device of claim 1,
The ultrasonic diagnostic apparatus according to claim 1, wherein the scanning method determination unit outputs an error signal when an appropriate image cannot be constructed. The device according to claim 7,
The ultrasonic diagnostic apparatus according to claim 1, wherein the scanning method determination unit outputs an error signal when a composite scan including a translation scan and a rotation scan is performed.

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