JP6793075B2 - Ultrasonic image processing equipment - Google Patents

Description

The present invention relates to an ultrasonic image processing apparatus.

An ultrasonic diagnostic apparatus is a typical example of an ultrasonic image processing apparatus that forms an ultrasonic image based on data obtained by transmitting and receiving ultrasonic waves. As the ultrasonic image, a two-dimensional image such as a B-mode image or a color Doppler image is well known. Further, there is also known a device for forming an ultrasonic image (three-dimensional ultrasonic image) that three-dimensionally projects a tissue or a foetation in a living body. For example, based on the volume data obtained three-dimensionally by transmitting and receiving ultrasonic waves, a rendering process is executed for each line of sight (ray) of a plurality of lines of sight to create an ultrasonic image that three-dimensionally projects the diagnosis target. The technique of forming is known.

For example, in Patent Document 1, in the voxel calculation executed for each line of sight (ray), when the sampling data to be the target of the voxel calculation is the data corresponding to the target tissue, the sampling interval is set in the middle of the voxel calculation. The technology to change closely is disclosed.

Further, Patent Document 2 discloses a technique of utilizing the opacity corrected according to the distance from the calculation start point in the voxel calculation in the opacity correction range on each line of sight (ray).

Japanese Unexamined Patent Publication No. 2008-113868 Japanese Unexamined Patent Publication No. 2008-18224

By the way, in the ultrasonic image formed by the rendering process based on the volume data, the image quality of the diagnosis target (for example, the degree of transparency of the image) may differ depending on the size of the diagnosis target. One factor is that the thickness of the diagnostic object (the data portion largely reflected in the image) on each line of sight depends on the size of the diagnostic object. For example, when the diagnosis target is a foetation, the size of the foetation varies greatly depending on the number of weeks, so that the effect on image quality becomes relatively remarkable.

Therefore, an object of the present invention is to realize a rendering process that suppresses fluctuations in image quality depending on the size of the diagnosis target.

An ultrasonic image processing apparatus suitable as an aspect of the present invention includes a rendering processing means that executes a rendering process for each line of sight of a plurality of lines of sight based on ultrasonic volume data, and a sampling interval of the rendering process on each line of sight. It is a means for determining the rendering pitch, which is based on the pitch determining means for determining the rendering pitch based on the size information of the diagnosis target and the pixel value obtained for each line of sight of a plurality of lines of sight by the rendering process. It is characterized by having an image forming means for forming an ultrasonic image to be diagnosed.

In the above configuration, the size information of the diagnosis target is information related to the size (size) of the diagnosis target. The size information of the diagnosis target includes information that directly indicates the size of the diagnosis target, such as the length, cross-sectional area, volume, and weight of the diagnosis target. Further, the size information of the diagnosis target may be information that indirectly indicates the size of the diagnosis target. For example, if the diagnosis target is a foetation, the standard size of the foetation can be known from the number of weeks of the foetation, and therefore the number of weeks of the foetation is also included in a suitable specific example of size information.

According to the above configuration, the rendering process for the diagnosis target can be executed at the rendering pitch determined based on the size information of the diagnosis target. For example, by changing the rendering pitch according to the size of the diagnosis target, it is possible to adjust the image quality of the ultrasonic image obtained by the rendering process (for example, the degree of transparency of the image). Thereby, for example, the fluctuation of the image quality depending on the size of the diagnosis target can be suppressed.

For example, the pitch determining means can determine a rendering pitch suitable for the diagnosis target based on the effective thickness obtained from the size information of the diagnosis target and the target sampling number for realizing the reference image quality. desirable. With this configuration, for example, a standard image quality can be realized regardless of the size of the diagnosis target.

Further, it is desirable that the ultrasonic image processing apparatus further has an opacity determining means for determining the opacity function used in the rendering process and determining the opacity function based on the rendering pitch. .. With this configuration, the rendering process can be executed using the opacity function determined based on the rendering pitch.

Further, the opacity determining means corresponds to the rendering pitch determined by the pitch determining means from among a plurality of opacity functions determined for each rendering pitch so that the influence of the opacity on the image is equal to each other. It is desirable to select the opacity function. For example, in the rendering process on each line of sight, it is possible to prepare a plurality of opacity functions so that the degree of opacity per unit length (effect on the image) becomes uniform regardless of the rendering pitch. desirable. With this configuration, for example, the effect of opacity on an image can be made uniform regardless of the rendering pitch.

Further, it is desirable that the pitch determining means determines a rendering pitch suitable for the foetation based on the number of weeks which is the size information of the foetation to be diagnosed. With this configuration, it is possible to obtain a rendering pitch suitable for the foetation from the number of weeks of the foetation.

Further, the functions corresponding to each part of the above-mentioned suitable ultrasonic image processing apparatus (including desirable specific examples) may be realized by a computer (including a tablet type terminal). For example, the computer is preferably described above by a program that causes the computer to realize the function as the rendering processing means, the function as the pitch determining means, the function as the image forming means, and the function as the opacity determining means. It can function as an ultrasonic image processing device. The program may be stored in a computer-readable storage medium such as a disk or memory and provided to the computer via the storage medium, or may be provided to the computer via a telecommunication line such as the Internet. May be provided.

According to the present invention, a rendering process that suppresses fluctuations in image quality depending on the size of a diagnosis target is realized. For example, according to a preferred embodiment of the present invention, the rendering process for the diagnostic target can be executed at a rendering pitch determined based on the size information of the diagnostic target, whereby, for example, it depends on the size of the diagnostic target. It is possible to suppress fluctuations in the image quality (for example, the degree of transparency of the image).

It is an overall block diagram of the ultrasonic diagnostic apparatus which is a preferable specific example of this invention. It is a figure which shows the specific example of a rendering process. It is explanatory drawing of the rendering process on each line of sight. It is a figure which shows the specific example of the correspondence relationship between the number of weeks of a foetation and the size of the foetation. It is a figure which shows the specific example of a plurality of opacity curves.

FIG. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus which is a preferable specific example of the ultrasonic image processing apparatus according to the present invention. The probe 10 is an ultrasonic probe for a three-dimensional image, and transmits and receives ultrasonic waves in a three-dimensional space including a diagnostic object such as a foetation. For example, a two-dimensional array probe (matrix array probe) having a plurality of two-dimensionally arranged vibrating elements, a mechanical probe for mechanically moving a plurality of one-dimensionally arranged vibrating elements, and the like are suitable for the probe 10. This is a concrete example.

The transmission / reception unit 12 has functions as a transmission beam former and a reception beam former. That is, the transmission / reception unit 12 forms a transmission beam by outputting a transmission signal to each of the plurality of vibration elements included in the probe 10, and further, for a plurality of received signals obtained from the plurality of vibration elements. The received beam is formed by performing phasing addition processing or the like.

Further, the transmission / reception unit 12 three-dimensionally scans an ultrasonic beam (transmission beam and reception beam) in, for example, a three-dimensional space including a diagnosis target. As a result, the received ultrasonic wave data is collected from within the three-dimensional space including the diagnosis target.

The volume configuration unit 20 forms volume data corresponding to the three-dimensional space by performing reconstruction processing on the received data obtained from the three-dimensional space. The volume configuration unit 20 performs reconstruction processing such as coordinate conversion processing and interpolation processing on the received data obtained in the scanning coordinate system (for example, rθφ coordinate system), and corresponds to the orthogonal coordinate system (for example, xyz coordinate system). Form the volume data. Volume data is composed of a plurality of voxel data arranged three-dimensionally in, for example, a data space of a Cartesian coordinate system.

The rendering processing unit 30 executes a rendering process (voxel calculation) based on a plurality of voxel data constituting the volume data.

FIG. 2 is a diagram showing a specific example of the rendering process. In the rendering process (rendering operation), a virtual viewpoint in calculation is set outside the volume data 32 corresponding to the three-dimensional space, and a plurality of lines of sight (rays) 34 are provided to the volume data 32 from the viewpoint side. Set. Further, an arithmetic screen 36 that functions as an image plane is set. Although the screen 36 is shown on the opposite side of the viewpoint with the volume data 32 in between in FIG. 2, the screen 36 may be arranged on the viewpoint side of the volume data 32.

In the rendering process, for each line of sight 34 of the plurality of line of sight (rays) 34 set for the volume data 32, a plurality of voxel data corresponding to the line of sight 34 is processed. For example, from a plurality of voxel data constituting the volume data 32, a plurality of voxel data corresponding to each line of sight 34 (arranged on each line of sight) can be obtained by interpolation processing or the like. Then, the rendering process is executed on each line of sight 34.

FIG. 3 is an explanatory diagram of the rendering process on each line of sight. In FIG. 3, one line of sight 34, which is a typical example of the plurality of line of sight 34, is shown, and a plurality of voxels arranged on the line of sight 34 are shown.

In the rendering process, for each line of sight 34, voxel operations based on the rendering method using opacity (opacity) are sequentially performed on a plurality of voxel data (voxel brightness information) corresponding to the line of sight 34 from the viewpoint side. Is executed. Then, as a result of the final voxel calculation for each line of sight 34, the luminance information corresponding to the line of sight 34 is determined.

The sampling interval of the rendering process (sequential voxel calculation) on each line of sight 34 is the rendering pitch (Rp). That is, the voxels on the line of sight 34 are sequentially targeted for calculation at the data interval determined by the rendering pitch, and the voxel calculation is sequentially executed.

Returning to FIG. 1, the rendering processing unit 30 sets the luminance information obtained for each line of sight from a plurality of lines of sight as the pixel value of each pixel by the rendering process, so that the pixel value of the plurality of pixels in the screen (image surface) is set. To get. As a result, projected image data of luminance information with the screen as the projection surface is formed.

The rendering pitch determination unit 40 determines the rendering pitch (Rp in FIG. 3), which is the sampling interval of the rendering process on each line of sight. The rendering pitch determination unit 40 determines the rendering pitch based on the size information of the diagnosis target. The rendering pitch is determined by using the effective thickness T obtained from the size information of the diagnosis target.

The effective thickness T is the thickness of the data reflected in the projected image data in the rendering process. For example, in the rendering process on the line of sight passing through the fetal head, the data corresponding to the tissue from the fetal scalp to the inside of the skull is largely reflected in the projected image, so that the data from the fetal scalp to the inside of the skull is greatly reflected. The thickness is the effective thickness T.

The rendering pitch determination unit 40 obtains the effective thickness T of the diagnosis target from the size information of the diagnosis target. One of the preferred specific examples of size information when the diagnosis target is a foetation is the number of weeks of the foetation.

FIG. 4 is a diagram showing a specific example of the correspondence between the number of weeks of a foetation and the size of the foetation. FIG. 4A is a graph showing the correspondence between the number of weeks of the foetation (horizontal axis) and the head diameter of the foetation (vertical axis). Further, FIG. 4B is a graph showing the correspondence between the number of weeks of the foetation (horizontal axis) and the total length of the foetation (vertical axis).

For example, as shown in FIG. 4, since the standard size (head diameter, total length, etc.) according to the number of weeks of the foetation is indexed, the standard size of the foetation is calculated from the number of weeks of the foetation. You can know. Then, the effective thickness T of the foetation is derived from the size of the foetation.

For example, if the diagnosis target is the head of a foetation, the effective thickness T of the foetation is a fixed ratio, for example, 10% of the head diameter obtained from the number of weeks of the foetation. This ratio is determined, for example, at the design stage of the ultrasonic diagnostic apparatus. Of course, the ratio may be switched for each application having a different target (for example, the heart), or the ratio may be adjusted by the user. When the entire body of the foetation is to be diagnosed, for example, the effective thickness T of the foetation may be determined according to the total length obtained from the number of weeks of the foetation. The number of weeks of the foetation to be diagnosed is specified by a user such as a doctor or a laboratory technician.

In addition, measured values such as the head diameter and the total length of the foetation to be diagnosed may be used as size information. For example, the effective thickness T of the foetation may be derived based on the measured values such as the head diameter and the total length measured by the ultrasonic diagnosis of the foetation to be diagnosed.

Returning to FIG. 1, the rendering pitch determination unit 40 determines the rendering pitch (Rp) suitable for the diagnosis target by, for example, the equation 1 based on the effective thickness T obtained from the size information of the diagnosis target and the target sampling number Na. To do. The target sampling number Na is the number of samples of the rendering process required to realize the reference image quality. For example, the target sampling number Na is determined at the design stage of the ultrasonic diagnostic apparatus of FIG. The configuration may be adjustable by the user.

Further, the rendering pitch determination unit 40 includes the effective thickness T obtained from the size information of the diagnosis target and the target sampling number Na, the density Sr of a plurality of lines of sight on the screen, and the length Pv of one voxel in the real space. May be used to determine the rendering pitch (Rp) suitable for the diagnosis target, for example, by the equation 2.

When the rendering pitch is determined, the opacity determining unit 50 determines the opacity function (opacity curve) used in the rendering process based on the determined rendering pitch. The opacity determination unit 50 selects, for example, an opacity curve corresponding to the rendering pitch determined by the rendering pitch determination unit 40 from a plurality of opacity curves determined for each rendering pitch.

FIG. 5 is a diagram showing a specific example of a plurality of opacity curves defined for each rendering pitch. FIG. 5 shows an opacity curve with the horizontal axis as the luminance value and the vertical axis as the opacity. In the rendering process for each line of sight, the opacity corresponding to the brightness value (voxel value) of each voxel is determined by using the opacity curve.

In FIG. 5, an opacity curve C1 corresponding to the reference rendering pitch “1”, an opacity curve C2 corresponding to the rendering pitch “3/4”, and an opacity curve C3 corresponding to the rendering pitch “1/2” are shown. , The capacity curve C4 corresponding to the rendering pitch "1/4" is shown.

For example, in the rendering process on each line of sight, a plurality of opacity curves C1 to C4 are defined so that the degree of opacity per unit length (effect on the image) becomes uniform regardless of the rendering pitch. Then, for example, data corresponding to a plurality of opacity curves C1 to C4 is stored in a memory or the like.

The opacity determination unit 50 (FIG. 1) selects, for example, an opacity curve corresponding to the rendering pitch determined by the rendering pitch determination unit 40 from a plurality of opacity curves determined for each rendering pitch. For example, if the determined rendering pitch is "1", the opacity curve C1 is selected, and if the determined rendering pitch is "1/2", the opacity curve C3 is selected.

FIG. 5 illustrates four opacity curves C1 to C4 as specific examples of the opacity curves, but a large number of opacity curves corresponding to a large number of five or more rendering pitches may be used. If there is no opacity curve corresponding to the same value as the determined rendering pitch, for example, the opacity curve corresponding to the value closest to the determined rendering pitch may be selected.

Further, for example, by correcting the opacity curve based on the rendering pitch, the opacity curve corresponding to the determined rendering pitch may be generated. For example, when only the opacity curve C1 corresponding to the reference rendering pitch "1" is predetermined and the determined rendering pitch is "1/2", the opacity curve C3 is generated by the correction processing for the opacity curve C1. May be done. Further, the opacity curve corresponding to an arbitrary rendering pitch may be derived by calculation.

Returning to FIG. 1, the rendering processing unit 30 uses the rendering pitch (Rp) determined by the rendering pitch determining unit 40 and the opacity curve determined by the opacity determining unit 50 to perform rendering processing (FIGS. 2 and 2). (See Fig. 3) is executed.

The image forming unit 60 forms an ultrasonic image based on the pixel values obtained for each of the plurality of lines of sight by the rendering process. The image forming unit 60 forms an ultrasonic image in which a diagnosis target such as a foetation is three-dimensionally projected based on the projected image data of the luminance information obtained from the rendering processing unit 30. The ultrasonic image formed in the image forming unit 60 is displayed on the display unit 62.

The control unit 100 controls the inside of the ultrasonic diagnostic apparatus of FIG. 1 as a whole. The overall control by the control unit 100 also reflects instructions received from users such as doctors and laboratory technicians via the operation device 70.

Among the configurations shown in FIG. 1, each unit of the transmission / reception unit 12, the volume configuration unit 20, the rendering processing unit 30, the rendering pitch determination unit 40, the opacity determination unit 50, and the image formation unit 60 includes, for example, an electric / electronic circuit, a processor, or the like. It can be realized by using hardware, and a device such as a memory may be used as needed in the realization. Further, at least a part of the functions corresponding to each of the above parts may be realized by a computer. That is, at least a part of the functions corresponding to each of the above parts may be realized by the cooperation of hardware such as a CPU, a processor, and a memory, and software (program) that defines the operation of the CPU and the processor.

Preferable specific examples of the display unit 62 are a liquid crystal display, an organic EL (electroluminescence) display, and the like. The operation device 70 can be realized by at least one of, for example, a mouse, a keyboard, a trackball, a touch panel, and other switches. The control unit 100 can be realized, for example, by cooperating with hardware such as a CPU, a processor, and a memory, and software (program) that defines the operation of the CPU and the processor.

Further, among the configurations shown in FIG. 1, for example, the functions of the rendering processing unit 30, the rendering pitch determining unit 40, the opacity determining unit 50, and the image forming unit 60 are realized by a computer, and the computer is made to function as an ultrasonic image processing device. You may.

Although preferred embodiments of the present invention have been described above, the above-described embodiments are merely examples in all respects, and do not limit the scope of the present invention. The present invention includes various modified forms without departing from its essence.

10 probe, 12 transmission / reception unit, 20 volume configuration unit, 30 rendering processing unit, 40 rendering pitch determination unit, 50 opacity determination unit, 60 image formation unit, 62 display unit, 70 operation device, 100 control unit.

Claims (4)

Based on the ultrasound volume data obtained by transmission and reception of ultrasonic for a three-dimensional space within a living body, to each of a plurality of line of sight of the sight line that is set for it, the luminance values for the sampled luminance value sequence Rendering processing means that executes rendering processing using the opacity determined for each, and
A means for determining a rendering pitch which is a sampling interval of the rendering process on each line of sight, and a pitch determining means for determining a rendering pitch based on size information of a diagnosis target in the three-dimensional space .
An opacity function selection means that selects an opacity function that determines opacity according to a luminance value in the rendering process according to the rendering pitch determined by the pitch determining means.
An image forming means for forming an ultrasonic image to be diagnosed based on a pixel value obtained for each line of sight of a plurality of lines of sight by the rendering process.
Have,
An ultrasonic image processing device characterized by this. In the ultrasonic image processing apparatus according to claim 1,
The pitch determining means determines a rendering pitch suitable for the diagnosis target based on the effective thickness obtained from the size information of the diagnosis target and the target sampling number for realizing the reference image quality.
An ultrasonic image processing device characterized by this. In the ultrasonic image processing apparatus according to claim 1 or 2.
The opacity function selection means selects an opacity function to be used from a plurality of opacity functions corresponding to a plurality of rendering pitches according to the rendering pitch determined by the pitch determining means.
An ultrasonic image processing device characterized by this. In the ultrasonic image processing apparatus according to any one of claims 1 to 3 ,
It said pitch determining means, based on the number of weeks is the size information of the fetus is the diagnosis target, and determines the rendering pitch adapted to the fetus,
An ultrasonic image processing device characterized by this.