JPH10277030A - Ultrasonic diagnostic system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve resolution or to improve frame rate in the case of image- displaying stereoscopic projection images by the transmission and reception of ultrasonic waves. SOLUTION: An ROI(region of interest) is specified on the stereoscopic projection images displayed at a display device 40 by using an ROI specifying part 42. Corresponding to the ROI, a mechanical scanning control part 34 controls the scanning range of the mechanical scanning direction of an array vibrator 22 and an electronic scanning control part 32 controls the scanning range of the electronic scanning direction of the array vibrator 22. Thus, the enlarged stereoscopic projection images are displayed at the display device 40. A resolution propriety mode or a frame rate priority mode is selected by a mode specifying part 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus for forming a three-dimensional projected image.

[0002]

2. Description of the Related Art 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-scale image. However, since only the cut surface of the tissue to be observed is expressed, it is difficult to recognize and grasp the tissue three-dimensionally on the image. On the other hand, an apparatus that transmits and receives ultrasonic waves to and from a three-dimensional region in a living body to form a three-dimensional image of a tissue is being put into practical use. The three-dimensional image is obtained, for example, by shading the tissue surface obtained by performing surface extraction to give a sense of depth, 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 formed 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 a three-dimensional area is temporarily stored in a three-dimensional echo data memory, and then each echo data is processed by software processing or the like. Need to be reconfigured. 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 represent the inside of the tissue through the tissue.

Accordingly, the applicant of the present application has filed a Japanese Patent Application No. 8-185.
No. 781 proposes a new image processing method. 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,
Alternatively, the translucent expression inside the tissue 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 echo data existing along the ultrasonic beam. The voxel calculation is executed until a predetermined end condition is satisfied. Then, the voxel operation value at the end point 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.

[0006]

The above-mentioned image processing method has an advantage that the image processing time can be reduced as compared with the conventional image processing method. However, since the ultrasonic beam needs to be two-dimensionally scanned, that is, the number of times of transmission / reception increases, there is a certain limitation in improving the frame rate.
In addition, the frame rate can be improved by reducing the number of ultrasonic beams set in the three-dimensional area (the number of times of transmission / reception).
In this case, the resolution decreases.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to improve the resolution in forming a three-dimensional projected image. Another object of the present invention is to improve a frame rate in forming a stereoscopic projection image.

[0008]

[Means for Solving the Problems]

(1) In order to achieve the above object, the present invention obtains echo data of each voxel in the three-dimensional area by scanning an ultrasonic beam and transmitting and receiving an ultrasonic wave to and from a three-dimensional area. Transmitting and receiving means, three-dimensional projected image forming means for forming a three-dimensional projected image of the three-dimensional area by sequentially executing a predetermined voxel operation for each voxel along the ultrasonic beam, and the three-dimensional area And a beam scanning control unit for limiting a scanning range of the ultrasonic beam according to the size of the region of interest. According to the above configuration, the region of interest is set in the three-dimensional region using the region of interest setting means, and scanning of the ultrasonic beam is performed in the region of interest. As described above, since the beam scanning range is limited, for example, if the number of beams per scan (frame rate) is maintained, the pitch between beams can be narrowed to improve the resolution. For example, if the pitch between beams is maintained, the number of beams can be reduced and the frame rate can be improved. The above-mentioned region of interest is desirably set by specifying a range on a three-dimensional projected image of a three-dimensional region.

In a preferred aspect of the present invention, the beam scanning control means has a function of adjusting a pitch between beams according to the size of the region of interest. Further, the beam scanning control means has a function of adjusting the number of beams according to the size of the region of interest.

In a preferred aspect of the present invention, the wave transmitting / receiving means includes electronic scanning means for electronically scanning the ultrasonic beam in the electronic scanning direction, and mechanical scanning means for mechanically scanning the ultrasonic beam in the mechanical scanning direction. An electronic scanning range and a mechanical scanning range are designated as the region of interest by the region of interest setting means, and the beam scanning control means causes the ultrasonic beam to scan in the electronic scanning range and the mechanical scanning range. It is characterized by.

Generally, the electronic scanning direction is orthogonal to the mechanical scanning direction, in other words, the scanning surface formed by the scanning of the ultrasonic beam is scanned in a direction perpendicular to the scanning direction.

[0012] (2) In a preferred embodiment of the invention, the stereoscopic projection image forming means, and opacity calculating means for calculating the opacity alpha _i voxel i based on the echo data e _i,
A transparency calculation means for calculating the transparency β _i of the voxel i based on the echo data e _i , a light emission calculation means for multiplying the echo data value e _i by the opacity α _i to calculate the light emission of the voxel i multiplied by the transparency of beta _i of voxel i to output light amount of the previous voxel i -1, adds a transmitted light quantity calculating means for calculating a quantity of transmitted light of the voxel i, and the amount of transmitted light and the light emission amount, the voxel i output And a light amount adding means for obtaining a light amount, wherein the three-dimensional projected image is formed by making the output light amount of the end voxel correspond to the pixel value.

In a preferred aspect of the present invention, the three-dimensional projection image forming means includes an opacity calculating means for calculating the opacity α _i of the voxel i based on the echo data ei;
The echo data e _i , the opacity α _i , and the input light amount C corresponding to the output light amount of the previous voxel i−1.
Output light amount calculating means for calculating the output light amount C _OUTi of the voxel i based on _INi , wherein the three-dimensional projection image is formed by making the output light amount of the end voxel correspond to the pixel value.

According to the above configuration, voxel processing using opacity or the like is performed along the ultrasonic beam. As a result, the sequentially captured echo data can be sequentially processed in real time in real time,
The three-dimensional data memory required in the conventional device can be eliminated. That is, the captured echo data is processed in the capturing order, and data processing can be sufficiently performed without temporarily storing all the echo data in the three-dimensional data memory.

Incidentally, the opacity α _i relates to the degree of diffusion and scattering of ultrasonic waves to the surroundings of the voxel i, and the amount of light emission indicates the intensity of the voxel i as a sound source (light source). Seem. 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 amount indicates the degree of contribution of the voxel i to the pixel value. This output light amount is transferred to voxel processing (calculation of transmitted light amount) of the next voxel. 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 three-dimensional projection image is formed as a set of those pixel values.

It has been confirmed by experiments that the ultrasonic image has both the characteristics as a projected 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, simultaneous observation of the surface and the inside of a fetus can be performed, and three-dimensional grasp of a tissue can be easily performed in diagnosing a disease.

Of course, by changing the definitions of the opacity and the transparency, it is possible to construct an ultrasonic image of a desired image quality, for example, 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 opacity and the like, and more specifically, can be performed by appropriately setting an end condition using 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 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.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of the apparatus configuration, a method of forming a three-dimensional projected image according to an embodiment will be described.

[Explanation of Image Forming Principle] The image processing method according to the present embodiment employs a known volume rendering (Volum rendering).
e Rendering) based on real-time image processing (especially 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. For this three-dimensional echo data capture space 12,
The voxel processing according to the present embodiment is performed along each ultrasonic beam, and the three-dimensional echo data capturing space 12 is projected on the projection plane 16 to obtain an ultrasonic image 100 shown in FIG.
It is. 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) is one in the ultrasonic image 100.
Corresponds to a pixel.

Here, voxel processing, which will be described in detail below, is performed on the acquired echo data in chronological order, so that each echo data is temporarily stored in a three-dimensional echo data memory to form an image. It is not necessary to read the echo data in the order necessary for the data processing, and the data processing synchronized with the data acquisition can be performed.

FIGS. 2 and 3 show the concept of the voxel 20. FIG. One voxel converts the received signal to A
It corresponds to one echo data obtained by the / D conversion, in other words, it corresponds to a volume (sample point) corresponding to one cycle of the A / D conversion rate. That is,
An ultrasound beam is assumed as a collection 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 is the luminance value P (x, 1) of one pixel constituting the ultrasonic image.
y).

Here, opacity α and transparency β [β = (1−α) in this 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,

Α = k1 · e ^k2 (1) Here, e is the value of the echo data, and k1 is a coefficient (parameter), which is variably set by the user. A numerical value larger than 1 is desirably 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 _{OU Ti} are defined, and the input light amount C _INi is the output light amount C _IN of the _immediately preceding voxel i-1. Equivalent to _{OU Ti-1} . That is,

## EQU2 ## There is a relationship of C _INi = C _OUTi-1 (2). However, C _{IN i} = 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 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.
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.

[0028]

C _OUTi = (1−α _i ) · C _INi + α _i · e _i (3) where C _INi = C _{OUTi−1 according} to 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 start 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 becomes 1 At the time when the processing has reached (end condition). However, even when the processing is the last (or the set depth) voxel L _LAST , the processing is terminated (forced termination condition). That is, the conditions under which the processing ends are as follows:

４α _i = 1 or i = L _LAST (4) The termination of the process when Σα _i = 1 means that the process is stopped when the sum of the opacity reaches 1.
Of course, the condition of the fourth expression, in particular, the maximum addition value (end determination value) of α _i may be changed according to the condition.

The output light-amount C _{OU T} of [0030] or more voxels at the time the end determination is made (final voxel) is brightness P (x, y) of the corresponding pixel is used as a. Then, when such pixel value calculation for each ultrasonic beam is performed for all ultrasonic beams, pixel values of all pixels constituting the ultrasonic image can be obtained. That is, one ultrasonic image is formed.

As shown by the above equation (3), the luminance value P of the pixel
(X, y) reflects the values of all echo data from the start voxel to the end voxel. But,
It reflects both scattering and absorption of ultrasonic waves at each voxel, not just simple integration as in the past. Therefore, an ultrasonic image having both the depth (three-dimensional) and transparent properties, such as an image formed by light transmitted from a light source and scattered and absorbed by each voxel, is obtained. Can be configured.

In the above formula (3), the transparency is defined by (1−α _i ), that is, the transparency can be represented by the opacity α _i , so the concept of transparency is apparently deleted from the arithmetic expression. be able to. Therefore, the output light amount C _OUTi can be calculated based on the same principle by _modifying the third expression as follows.

[0033]

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 )) The above equation 5-1 is obtained by rewriting the third equation, and the second term is replaced with Δ _i. , 5-2. That is, the output light amount C _OUTi of voxel i is _equal to the input light amount C _OUTi.
It is defined as the sum of the corrected amount delta _i in _INi.
As is clear from the above equation transformation 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] Next, a preferred embodiment of the ultrasonic diagnostic apparatus according to the present invention to which the above principle is applied will be described with reference to FIG. FIG. 5 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus.

In FIG. 5, the ultrasonic probe 8 for capturing three-dimensional echo data includes an array transducer 22 and a mechanical scanning mechanism. Here, the array vibrator 22 is one in which a plurality of ultrasonic vibrating elements are linearly arranged and arranged, and an ultrasonic beam is scanned by electronically scanning the array vibrator 22, thereby forming the scanning surface 10. You. In FIG. 5, the electronic scanning direction is shown as the X direction. Y
The direction indicates the ultrasonic beam direction or the depth direction.

The above-described mechanical scanning mechanism includes a drive motor 25, and an encoder 26 as a position detector is connected to the drive motor 25. The array vibrator 22 is driven by the motor 25 in the mechanical scanning direction. The mechanical scanning direction is shown as a Z direction in FIG.
In that case, the position of each scanning surface 10 is detected by the encoder 26. By performing mechanical scanning while performing electronic scanning, as shown in FIG.
0 is formed, thereby forming a three-dimensional data acquisition space.

The transmission / reception unit 30 is controlled by the electronic scanning control unit 32. A transmission signal is supplied from the transmission / reception unit 30 to the array transducer 22, and a reception signal from the array transducer 22 is input to the transmission / reception unit 30. Transceiver 30
Includes an amplifier and a detector.

The electronic scanning control section controls the electronic scanning range of the array transducer 22, that is, controls the range in which transmission and reception are performed, as described later. The mechanical scan control unit 34 supplies a drive signal to the drive motor 25 described above, and the mechanical scan control unit 34 sets a scan range in the machine scan direction. That is,
X by the electronic scanning control unit 32 and the mechanical scanning control unit 34
The scanning range in the direction and the Z direction is defined.

The reception signal output from the transmission / reception unit 30 is input to a stereoscopic projection image forming unit (Vol-mode calculation unit) 36. The three-dimensional projected image forming unit 36 forms a three-dimensional projected image as a three-dimensional image based on the above-described image processing principle. That is, the three-dimensional projection image forming unit 36 executes a voxel operation for each voxel along the ultrasonic beam, and outputs the output light quantity of the end voxel to a DSC (digital scan converter) 38 as a pixel value.

The DSC 38 is provided with a frame memory, in which image data of a stereoscopic projected image is stored. In this case, one scanning plane
A three-dimensional projection image for a line is formed, and such a three-dimensional projection image is constructed by aligning the image data of each scanning plane based on the output signal of the encoder 26, that is, the Z coordinate. The display 40 displays such a stereoscopic projected image. An example of a stereoscopic projection image is shown in the left diagram of FIG. In this example, a stereoscopic projection image of a fetus is shown.

ROI (region of interest) designation section 4 in FIG.
2 is composed of, for example, a trackball and a keyboard provided in the ultrasonic diagnostic apparatus.
The ROI is specified on the stereoscopic projection image by the user using the I specifying unit 42. The ROI designation state is shown in the left diagram of FIG. In the present embodiment, R
A rectangular area can be designated as OI.

The ROI coordinate calculation unit 44 includes the ROI designation unit 4
2 is interpreted to determine, for example, the upper left corner coordinates and the lower right corner coordinates of the ROI, and output their coordinate data. In the coordinate form shown in FIG. 5, since the X direction is the electronic scanning direction and the Z direction is the mechanical scanning direction, respective ranges are set in the X direction and the Z direction on the stereoscopic projected image. . Incidentally, the Y direction is the direction of the ultrasonic beam, and the calculation range along the direction of the ultrasonic beam is determined for each ultrasonic beam based on the condition of the above-described formula (4).

In this embodiment, the coordinates (x1, z1) of the upper left corner and the coordinates (x2, z2) of the lower right corner of the ROI are determined by the mechanical scanning control unit 34, the electronic scanning control unit 32, and the DSC 38.
Is output to The mechanical scanning control unit 34 sets the mechanical scanning range of the array transducer 22 in the range from the coordinates z1 to z2. Further, the electronic scanning control unit 32 controls the transmitting / receiving unit 3 so that the electronic scanning is performed in the range from the coordinates x1 to x2.
0 is controlled. The coordinates are also used in the DSC 38 to construct a stereoscopic projection image of the ROI. The three-dimensional projected image formed in the ROI is shown in the right diagram of FIG. As a result, a part of the target object is displayed enlarged.

In the ultrasonic diagnostic apparatus according to the present embodiment, two operation modes can be selected when specifying the ROI. One is a resolution priority mode, and the other is a frame rate priority mode. This will be described with reference to FIG. Although the scanning range of the ultrasonic beam in the electronic scanning direction is shown in FIG. 6, in each mode, the same control as that shown in FIG. 6 is performed in the mechanical scanning direction.

In the normal mode shown in FIG. 6A, the ultrasonic beam 102 is scanned over the entire scanning range by electronically scanning the array transducer 22.

On the other hand, in the resolution priority mode shown in FIG. 6B, the ultrasonic beam 10 is set only within the range of the ROI specified by the ROI specifying section 42 described above.
2 is electronically scanned. In the resolution priority mode, the number of the ultrasonic beams 102 in the normal mode is maintained as it is. As a result, the resolution is improved although the frame rate is not changed. That is, it is possible to form a high-resolution stereoscopic projection image by increasing the pitch between the ultrasonic beams.

On the other hand, in the frame rate priority mode shown in FIG. 6C, the electronic scanning of the ultrasonic beam 102 is performed only in the set ROI, as in the resolution priority mode. In the mode, the pitch between the ultrasonic beams is maintained as in the normal mode, and the number of the ultrasonic beams is reduced instead. In this case, the resolution is not improved because the pitch between the ultrasonic beams is maintained, but the frame rate can be improved because the number of times of transmission and reception is reduced.

Therefore, when it is desired to display each part roughly and enlarged, the frame rate priority mode may be selected. On the other hand, when a specific part is observed in detail, the resolution priority mode is selected. Is done. That is, there is an advantage that the user can arbitrarily select an operation mode according to the purpose of diagnosis. As described above, FIG.
Is shown only for electronic scanning, but the same applies to mechanical scanning. In some cases, different operation modes may be selected for electronic scanning and mechanical scanning. Generally, mechanical scanning is slower than electronic scanning,
It is also possible to select the frame rate priority mode for the mechanical scanning direction and select the resolution priority mode for the electronic scanning.

[0049]

As described above, according to the present invention,
In forming a stereoscopic projection image, the resolution can be improved, or the frame rate can be improved. Also,
According to the present invention, an appropriate operation mode can be selected according to a diagnosis purpose or the like.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a relationship between a three-dimensional echo data capturing space and a three-dimensional projected image.

FIG. 2 is a diagram illustrating a relationship between an input light amount and an output light amount of each voxel.

FIG. 3 is a diagram showing a light emission amount of each voxel.

FIG. 4 is a diagram for explaining an output light amount of a voxel.

FIG. 5 is a block diagram showing an overall configuration of an ultrasonic diagnostic apparatus according to the present invention.

FIG. 6 is an explanatory diagram showing an operation in each operation mode.

FIG. 7 is a diagram illustrating a display example of a stereoscopic projection image.

[Explanation of symbols]

8 Ultrasonic probe for capturing 3D echo data, 10
Scanning plane, 12 3D echo data acquisition space, 20
Voxel, 22 array transducer, 32 electronic scanning control unit, 34 mechanical scanning control unit, 36 stereoscopic projection image forming unit (Vol-mode calculation unit), 42 ROI designation unit,
44 ROI coordinate calculation unit, 50 mode designation unit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masaki Hirose 6-22-1, Mure, Mitaka-shi, Tokyo Aloka Co., Ltd.

Claims (6)

[Claims] A transmitting / receiving unit for obtaining echo data of each voxel in the three-dimensional region by transmitting and receiving an ultrasonic wave to and from a three-dimensional region by scanning an ultrasonic beam; Three-dimensional projection image forming means for forming a three-dimensional projection image of the three-dimensional region by sequentially executing a predetermined voxel operation for each voxel along the region, a region of interest for setting a region of interest in the three-dimensional region An ultrasonic diagnostic apparatus comprising: setting means; and beam scanning control means for limiting a scanning range of an ultrasonic beam according to a size of the region of interest. 2. An ultrasonic diagnostic apparatus according to claim 1, wherein said beam scanning control means has a function of adjusting a pitch between beams according to a size of said region of interest. 3. An ultrasonic diagnostic apparatus according to claim 1, wherein said beam scanning control means has a function of adjusting the number of beams according to the size of said region of interest. 4. The apparatus according to claim 1, wherein the transmitting and receiving means includes electronic scanning means for electronically scanning the ultrasonic beam in the electronic scanning direction, and mechanical scanning means for mechanically scanning the ultrasonic beam in the mechanical scanning direction. An electronic scanning range and a mechanical scanning range are designated as the region of interest by the region of interest setting unit, and the beam scanning control unit performs scanning of an ultrasonic beam in the electronic scanning range and the mechanical scanning range. An ultrasonic diagnostic apparatus characterized by performing the following. 5. The apparatus according to claim 1, wherein said stereoscopic projection image forming means calculates opacity α _i of voxel i based on echo data e _i , and opacity calculating means based on echo data e _i A transparency calculating means for calculating the transparency β _i of the voxel i, and multiplying the echo data e _i by the opacity α _i to obtain a voxel i
A light emission amount calculating means for calculating the light emission amount of the voxel i; a transmitted light amount calculating means for calculating the transmitted light amount of the voxel i by multiplying the output light amount of the previous voxel i-1 by the transparency β _i of the voxel i; And a light amount adding means for adding the amount of light and the amount of transmitted light to obtain an output light amount of the voxel i, wherein the three-dimensional projection image is formed by making the output light amount of the end voxel correspond to a pixel value. Ultrasound diagnostic equipment. 6. The apparatus of claim 1, wherein the stereoscopic projection image forming means, and opacity calculating means for calculating the opacity alpha _i voxel i based on the echo data e _i, the echo data e _i, The opacity α _i and the input light amount C corresponding to the output light amount of the previous voxel i−1.
Output light amount calculating means for calculating the output light amount C _OUTi of the voxel i based on _INi , wherein the three-dimensional projected image is formed in such a manner that the output light amount of the end voxel corresponds to the pixel value. Ultrasound diagnostic device.