JP2014124231A - Ultrasonic inspection device, and signal processing method and program of ultrasonic inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic inspection device, and a signal processing method and a program of the ultrasonic inspection device capable of calculating an appropriate optimum sound velocity value while preventing an increase in an arithmetic load, and acquiring a high-quality image even while changing an observation position or searching for an observation position by moving an ultrasonic probe, and even when a fast-moving organ is an observation object.SOLUTION: An ultrasonic inspection device includes: an image analysis unit for calculating an amount of image variations between a plurality of ultrasonic image data generated at different timings; a sound velocity determination unit for determining an optimum sound velocity value and updating the optimum sound velocity value; and an update necessity determination unit for determining that the update of the optimum sound velocity value by the sound velocity determination unit should be performed when the amount of image variations calculated by the image analysis unit is larger than a predetermined threshold.

Description

  The present invention relates to an ultrasonic inspection apparatus that performs imaging of an inspection target such as an organ in a living body by transmitting and receiving an ultrasonic beam, and generates an ultrasonic image used for inspection and diagnosis of the inspection target. The present invention also relates to a signal processing method and program for an ultrasonic inspection apparatus.

  Conventionally, in the medical field, ultrasonic inspection apparatuses using ultrasonic images have been put into practical use. In general, this type of ultrasonic inspection apparatus has an ultrasonic probe with a built-in transducer array and an apparatus main body connected to the ultrasonic probe, and ultrasonic waves are directed from the ultrasonic probe into the subject. An ultrasonic image is generated by transmitting a beam, receiving an ultrasonic echo from within the subject with an ultrasonic probe, and electrically processing the received signal with the apparatus main body.

When an ultrasonic image is generated in an ultrasonic inspection apparatus, it is assumed that the sound speed in the living body of the subject is constant, and is delayed with respect to reception signals (element data) received by each transducer of the ultrasonic probe. A sound ray signal is generated by correcting and synthesizing the time (phased addition). Further, an ultrasonic image is generated from the generated sound ray signal. However, since there is a variation in the actual sound speed value in the living body, this variation causes a spatial distortion in the ultrasonic image.
On the other hand, in recent years, in order to more accurately diagnose the diagnostic region in the subject, the imaging region is divided into a plurality of regions, and an appropriate sound velocity value is measured for each divided region, and this sound velocity value is calculated. The distortion of an image is corrected by using it to generate an ultrasonic image (Patent Document 1).

  Also, it is considered that an ultrasonic inspection apparatus detects a change in an ultrasonic image and changes the process according to the change in the image.

  For example, in Patent Document 2, luminance data at a certain position is compared with luminance data at the same position in the previous loop, and if the difference between these two data exceeds a predetermined threshold value, It is described that it is determined that there is motion at a position, and a region where it is determined that there is motion is to scan the gap between the transmitted sound rays with a new sound ray.

JP 2010-99452 A JP-A-2005-427

  As described in Japanese Patent Application Laid-Open No. 2004-228688, the optimal sound speed value is measured, and the ultrasonic image is generated based on the optimal sound speed value, thereby improving the accuracy of the ultrasonic image. However, since the calculation load for calculating the optimum sound speed value is large, calculating the optimum sound speed value at every frame or at a short frame interval increases the calculation load, and the real-time property of displaying an ultrasonic image is poor. There was a problem of becoming. Therefore, if the interval for calculating the optimum sound speed value is lengthened, the calculation load is reduced, and the real-time property of the ultrasonic image display can be prevented from being lowered.

  However, if the interval for calculating the sound velocity value is increased, for example, when the observation position is changed by moving the ultrasonic probe, or when the observation position is searched, or when an organ with a fast movement such as the heart is to be observed. Causes a gap between the calculated sound speed value and the optimum sound speed value at the actually observed position, and even if an image is generated using the calculated sound speed value, a high-quality image cannot be obtained. There was a problem.

  In Patent Document 2, although it is described that the image quality is improved by increasing the number of sound rays to be scanned in a region where there is a motion, no consideration is given to obtaining an optimum sound speed value.

  The object of the present invention is to solve the above-mentioned problems of the prior art, change the observation position by moving the ultrasonic probe, search for the observation position, or target a fast-moving organ as the observation target. The present invention also provides an ultrasonic inspection apparatus, an ultrasonic inspection apparatus signal processing method, and a program capable of calculating an appropriate optimum sound velocity value and obtaining a high-quality image while preventing an increase in calculation load. For the purpose.

  In order to achieve the above object, the present invention is an ultrasonic inspection apparatus that inspects an inspection object using an ultrasonic beam, and transmits an ultrasonic beam and is reflected by the inspection object. A transducer array that receives an echo and outputs an element signal corresponding to the received ultrasonic echo, and a transmission that transmits an ultrasonic beam to the transducer array using the plurality of elements. A receiving unit that performs predetermined processing on an element signal output by receiving and outputting ultrasonic echoes from a plurality of elements of the transducer array, and receiving the element data output by the receiving unit Generated by a signal storage unit, an image generation unit that generates a sound ray signal by phasing and adding element data based on a predetermined sound velocity value, and generating ultrasonic image data from the sound ray signal, and an image generation unit Ultrasonic image data An image memory to be stored, an image analysis unit for calculating an image variation amount between a plurality of ultrasonic image data generated at different timings, and a plurality of predetermined set sound speeds using element data stored in the received signal storage unit Based on a plurality of ultrasonic image data generated by the image generation unit, respectively, an optimal sound speed value is determined, and an optimal sound speed value is updated, and an image fluctuation amount calculated by the image analysis unit is a predetermined threshold value An update necessity determination unit that determines whether or not to determine and update the optimum sound speed value by the sound speed determination unit when the image variation amount is larger than a predetermined threshold. An ultrasonic inspection apparatus is provided.

Here, it is preferable that the update necessity determination unit determines that the optimum sound speed value needs to be updated when the image fluctuation amount changes from a predetermined threshold value or less to a value larger than the predetermined threshold value.
Further, when the update necessity determination unit determines that the update of the optimum sound speed value is necessary, the transmission unit causes the transducer array to transmit an ultrasonic beam for sound speed update, and the sound speed determination unit performs the sound speed update. It is preferable to determine the optimum sound speed value using the element data obtained by transmitting the ultrasonic beam for the purpose and update the optimum sound speed value.
Further, it is preferable that the image analysis unit calculates an image fluctuation amount between the latest ultrasonic image data and the ultrasonic image data acquired before a predetermined frame from the latest ultrasonic image data.

Alternatively, the image analysis unit preferably calculates an image fluctuation amount between the latest ultrasonic image data and the ultrasonic image data generated using the element data when the optimum sound speed is updated. .
Further, the update necessity determination unit determines that the optimum sound speed value needs to be updated when the image variation amount is larger than a predetermined first threshold value and smaller than a second threshold value larger than the first threshold value. Is preferred.

  In order to achieve the above object, the present invention transmits an ultrasonic beam, receives an ultrasonic echo reflected in the inspection object, and outputs an element signal corresponding to the received ultrasonic echo. A signal processing method of an ultrasonic inspection apparatus that generates ultrasonic image data by generating an ultrasonic beam by a transducer array in which a plurality of elements are arranged, and inspecting an inspection target, A transmission step of transmitting an ultrasonic beam to the child array using a plurality of elements, and element signals output by receiving the ultrasonic echoes from the plurality of elements of the transducer array are subjected to predetermined processing as element data. A receiving step for outputting, a received signal storing step for storing element data output by the receiving step, and a phasing addition of the element data based on a predetermined sound velocity value to generate a sound ray signal; An image generation step for generating wave image data, an image storage step for storing ultrasonic image data generated in the image generation step, and an image variation amount between a plurality of ultrasonic image data generated at different timings are calculated. An optimum sound speed value is determined from a plurality of ultrasonic image data generated in the image generation step based on a plurality of predetermined set sound speeds using the element data stored in the image analysis step and the received signal storage step, A sound speed determination step for updating the optimum sound speed value; and determining whether or not the image fluctuation amount calculated in the image analysis step is larger than a predetermined threshold value. If the image fluctuation amount is larger than the predetermined threshold value, the sound speed determination step And determining whether or not the optimum sound speed value is to be determined and updated, and determining whether or not to update. To provide a method.

  In order to achieve the above object, the present invention transmits an ultrasonic beam, receives an ultrasonic echo reflected in the inspection object, and outputs an element signal corresponding to the received ultrasonic echo. A computer executes a signal processing method of an ultrasonic inspection apparatus that generates an ultrasonic beam by using a transducer array in which a plurality of elements are arranged, inspects an inspection object, and generates ultrasonic image data. The program includes a transmission step for transmitting an ultrasonic beam to the transducer array using a plurality of elements, and a predetermined process for an element signal that the plurality of elements of the transducer array receive and output an ultrasonic echo. A receiving step for outputting the data as element data, a reception signal storing step for storing the element data output by the receiving step, and phasing and adding the element data based on a predetermined sound velocity value An image generation step for generating a line signal and generating ultrasonic image data from the sound ray signal, an image storage step for storing the ultrasonic image data generated in the image generation step, and a plurality of times generated at different timings An image analysis step for calculating an image variation amount between the ultrasonic image data and a plurality of super images generated in the image generation step based on a plurality of predetermined set sound speeds using the element data stored in the received signal storage step. An optimal sound speed value is determined from the sound wave image data, the sound speed determination step for updating the optimal sound speed value, and whether or not the image fluctuation amount calculated in the image analysis step is larger than a predetermined threshold value. An update necessity determination step for determining that the optimum sound speed value is determined and updated in the sound speed determination step when the threshold value is larger than the predetermined threshold value. To provide an ultrasonic inspection device signal processing program, characterized in that to execute the data.

  According to the present invention, since the image fluctuation amount is calculated and the optimum sound speed value is updated when the image fluctuation amount is larger than a predetermined threshold, the observation position can be changed by moving the ultrasonic probe or the observation position can be changed. Even when searching or when a fast-moving organ is an observation target, an appropriate optimum sound speed value can be calculated, and a high-quality image can be obtained.

It is a block diagram which shows notionally the structure of the ultrasonic inspection apparatus which concerns on this invention. (A) is a figure which shows notionally the arrangement | positioning of the transmission focus of a normal ultrasonic beam, (B) is a figure which shows notionally the arrangement | positioning of the transmission focus of the ultrasonic beam for sound speed update. . It is a graph for demonstrating determination of the sound speed update in an update necessity determination part. It is a graph for demonstrating another example of the determination of the sound speed update in an update necessity judgment part. It is a graph for demonstrating another example of the determination of the sound speed update in an update necessity judgment part. (A) is a figure which shows notionally the image in which the attention area | region was set, (B) is a figure which shows notionally the arrangement | positioning of the transmission focus of an ultrasonic beam. (A)-(D) is a figure which shows notionally the arrangement | positioning of the transmission focus of an ultrasonic beam.

Hereinafter, an ultrasonic inspection apparatus according to the present invention, and a signal processing method and program of the ultrasonic inspection apparatus will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 shows a configuration of an ultrasonic inspection apparatus according to Embodiment 1 of the present invention. The ultrasonic inspection apparatus includes the ultrasonic probe 12 including the transducer array 42, and the transmission circuit 14 and the reception circuit 16 are connected to the transducer array 42. To the receiving circuit 16, a phasing addition unit 44, a detection processing unit 46, a DSC (Digital Scan Converter) 48 and an image processing unit 50, and a display control unit 32 and a display unit 34 of the image generation unit 18 are sequentially connected. An image memory 52 is connected to the image processing unit 50.

The reception signal storage unit 22 is connected to the reception circuit 16 and the phasing addition unit 44, the sound speed determination unit 24 is connected to the phasing addition unit 44 and the image memory 52, and the sound speed determination unit 24 and the phasing addition unit 44 are connected. A sound speed storage unit 30 is connected. Further, an image analysis unit 26 is connected to the image memory 52, and an update necessity determination unit 28 is connected to the transmission circuit 14, the sound speed determination unit 24, and the image analysis unit 26.
Further, the transmission circuit 14, the reception circuit 16, the image generation unit 18, the display control unit 32, the reception signal storage unit 22, the sound speed determination unit 24, the image analysis unit 26, the update necessity determination unit 28, and the sound speed storage unit 30 are controlled by the control unit. 36 is connected, and an operation unit 38 and a storage unit 40 are connected to the control unit 36, respectively.

The ultrasonic probe 12 has a transducer array (array transducer) 42 used in a normal ultrasonic inspection apparatus.
The transducer array 42 has a plurality of ultrasonic transducers arranged one-dimensionally or two-dimensionally. Each of these ultrasonic transducers transmits an ultrasonic wave according to a drive signal supplied from the transmission circuit 14 and receives an ultrasonic echo from a subject to output a reception signal. Each ultrasonic transducer is, for example, a piezoelectric ceramic represented by PZT (lead zirconate titanate), a polymer piezoelectric element represented by PVDF (polyvinylidene fluoride), or PMN-PT (magnesium niobate / lead titanate). It is constituted by a vibrator in which electrodes are formed on both ends of a piezoelectric body made of a piezoelectric single crystal represented by a solid solution).

  When a pulsed or continuous wave voltage is applied to the electrodes of such a vibrator, the piezoelectric body expands and contracts, and pulsed or continuous wave ultrasonic waves are generated from the respective vibrators, and the synthesis of those ultrasonic waves. As a result, an ultrasonic beam is formed. In addition, each vibrator expands and contracts by receiving propagating ultrasonic waves to generate electric signals, and these electric signals are output as ultrasonic reception signals (analog element signals).

  The transmission circuit 14 includes, for example, a plurality of pulse generators, and is transmitted from the plurality of ultrasonic transducers of the transducer array 42 based on the transmission delay pattern selected according to the control signal from the control unit 36. The ultrasonic waves to be supplied are supplied to a plurality of ultrasonic transducers by adjusting the delay amount of each drive signal so as to form an ultrasonic beam forming a predetermined transmission focal point.

  Here, in order to acquire one ultrasonic image, it is necessary to transmit an ultrasonic beam to each of a plurality of predetermined transmission focal points. In the present embodiment, the transmission focus arrangement pattern includes an arrangement pattern for acquiring B-mode image data (B-mode pattern) and a sound speed update arrangement pattern (sound speed update pattern).

FIG. 2A is a diagram conceptually illustrating an example of a B mode pattern, and FIG. 2B is a diagram conceptually illustrating an example of a sound speed update pattern.
In the example shown in FIG. 2A, in the B mode pattern, three transmission focal points are set on a predetermined transmission line. When performing transmission for acquiring B-mode image data, the transmission circuit 14 causes the transducer array 42 to transmit an ultrasonic beam according to the B-mode pattern.

In the example shown in FIG. 2B, the sonic update pattern has five transmission focal points set on a predetermined transmission line. In this way, in the sound speed update pattern, more transmission focal points are set than in the B mode pattern. When the transmission circuit 14 receives a signal to update the sound speed from the update necessity determination unit 28 described later, the transmission circuit 14 causes the transducer array 42 to transmit an ultrasonic beam according to the sound speed update pattern.
Note that B-mode image data is also created in the case of transmission / reception of ultrasonic waves according to the sonic speed update pattern.

In the illustrated example, three transmission focal points are set for one transmission line in the B-mode pattern, but the present invention is not limited to this, and it may be one or two, or four or more.
In addition, the sound speed update pattern has five transmission focal points set for one transmission line, but is not limited to this, and may be larger than the B mode pattern. Further, the sound speed update pattern may have the same transmission focal number as the B-mode pattern. That is, a configuration having one transmission pattern may be used.
By increasing the number of transmission focal points of the sound speed update pattern, the optimum sound speed value can be obtained with higher accuracy.

  In response to a control signal from the control unit 36, the receiving circuit 16 causes the transducer array 42 to transmit ultrasonic echoes generated by the interaction between the ultrasonic beam transmitted from the transducer array 42 and the subject. Received and output received signals, that is, analog element signals for each ultrasonic element are amplified and A / D converted to generate and output digitized element data.

Specifically, the receiving circuit 16 amplifies a plurality of analog element signals received by a plurality of ultrasonic elements, performs A / D conversion in response to one transmission of the ultrasonic beam, and receives the received ultrasonic waves. Output as digital element data including element information and reception time information.
The receiving circuit 16 receives an ultrasonic echo and outputs element data each time an ultrasonic beam is transmitted by the transmitting circuit 14 once. Accordingly, a plurality of element data corresponding to each transmission is output in response to the transmission circuit 14 transmitting the ultrasonic beam a plurality of times for each frame.
Here, in the present invention, one frame corresponds to one ultrasonic image, and therefore, ultrasonic waves are transmitted and received a plurality of times in one frame.
The reception circuit 16 supplies the output element data to the phasing addition unit 44 and the reception signal storage unit 22 of the image generation unit 18.

  The reception signal storage unit 22 sequentially stores element data output from the reception circuit 16. The reception signal storage unit 22 associates information about the frame rate input from the control unit 36 (for example, parameters indicating the depth of the reflection position of the ultrasonic wave, the density of the scanning line, and the visual field width) with the element data. Store.

The image generation unit 18 generates a sound ray signal from the element data supplied from the reception circuit 16 or the reception signal storage unit 22 under the control of the control unit 36, and generates an ultrasonic image from the sound ray signal. is there.
The image generation unit 18 includes a phasing addition unit 44, a detection processing unit 46, a DSC 48, an image processing unit 50, and an image memory 52.

  The phasing addition unit 44 applies each element signal of the element data generated by the receiving circuit 16 according to an optimum sound speed value supplied from a sound speed storage unit 30 described later or a set sound speed input from the sound speed determination unit 24. The delay correction data is generated by performing the delay correction, and the delay correction data is added to perform the reception focus process. By this reception focus processing, reception data (sound ray signal) in which the focus of the ultrasonic echo is narrowed is generated.

Here, when generating normal B-mode image data, the phasing addition unit 44 reads the optimum sound speed value from the sound speed storage unit 30 and performs reception focus processing on the element data.
Further, the phasing addition unit 44 reads out element data obtained from ultrasonic waves transmitted / received according to the sound speed update pattern from the reception signal storage unit 22 when the sound speed determination unit 24 determines the optimum sound speed value. Based on the set sound speed supplied from the sound speed determination unit 24, reception focus processing is performed on the read element data to generate reception data. Since a plurality of set sound speeds are supplied from the sound speed determination unit 24, the phasing / addition unit 44 performs reception focus processing on the element data for each of the set sound speeds supplied from the sound speed determination unit 24, and receives the received data. Generate.
The phasing addition unit 44 supplies the reception data to the detection processing unit 46.

The detection processing unit 46 corrects attenuation according to the distance according to the depth of the reflection position of the ultrasonic wave on the reception data generated by the phasing addition unit 44, and then performs envelope detection processing to perform detection. B-mode image data that is tomographic image information related to the tissue in the specimen is generated.
A DSC (digital scan converter) 48 converts (raster conversion) the B-mode image data generated by the detection processing unit 46 into image data according to a normal television signal scanning method.

The image processing unit 50 performs various necessary image processing such as gradation processing on the B-mode image data input from the DSC 48 to create B-mode image data for use in inspection and display, and then creates the created B-mode image data. The mode image data is output to the display control unit 32 for display or stored in the image memory 52.
The image memory 52 temporarily stores the B-mode image data created by the image processing unit 50. The B-mode image data stored in the image memory 52 is read by the display control unit 32 for display on the display unit 34 as necessary. In addition, the B-mode image data generated when the sound speed determination unit 24 determines the sound speed value and stored in the image memory 52 is read by the image analysis unit 26.
The image memory 52 preferably stores all captured B-mode image data.

The display control unit 32 displays an ultrasound image on the display unit 34 based on the B-mode image data that has been subjected to image processing by the image processing unit 50.
The display unit 34 includes a display device such as an LCD, for example, and displays an ultrasonic image under the control of the display control unit 32.

The sound speed determination unit 24 gives a plurality of set sound speeds to the phasing addition unit 44 according to a signal from the update necessity determination unit 28 described later, and is generated by the image generation unit 18 and stored in the image memory 52. The mode image data is analyzed, and the sound speed value at which the contrast or sharpness is highest for each image area is determined as the optimum sound speed value. The sound speed determination unit 24 stores a predetermined set sound speed.
In the present invention, the optimum sound velocity value of the region is that from the ultrasonic probe 12 when it is assumed that the space between the region and the ultrasonic probe 12 (the transducer array 42) is filled with a uniform material. It represents the sound velocity value up to the region. That is, the average sound speed between the region and the ultrasonic probe 12. This is also called ambient sound velocity.

  Specifically, the sound speed determination unit 24 gives a plurality of predetermined set sound speeds V in increments of ΔV from Vst to Vend to the phasing addition unit 44 according to the signal from the update necessity determination unit 28. Next, the sound speed determination unit 24 reads the B-mode image data that the image generation unit 18 reads the element data from the reception signal storage unit 22, generates based on each set sound speed V, and stores it in the image memory 52. Here, the read B-mode image data is B-mode image data generated by using the element data obtained by transmission and reception according to the sound speed update pattern in the image generation unit 18.

  The sound speed determination unit 24 calculates the contrast or sharpness of the read B-mode image data for each preset area, and determines the set sound speed V that provides the highest contrast or sharpness as the optimum sound speed in this area. The sound speed determination unit 24 supplies the value of the optimum sound speed for each area determined to be the optimum sound speed to the sound speed storage unit 30 as a sound speed map, and updates the optimum sound speed value stored in the sound speed storage unit 30.

Note that the search range for the set sound speed V may be, for example, Vst of 1400 m / s, Vend of 1700 m / s, and ΔV of about 10 to 50 m / s.
The sound speed determination unit 24 is configured to divide an image into a plurality of predetermined areas and determine the optimum sound speed for each area. However, the present invention is not limited to this, and the image is not divided into a plurality of areas. The optimum sound speed value may be determined as a whole.

The sound speed storage unit 30 is a part that stores the optimum sound speed value determined by the sound speed determination unit 24.
The sound speed storage unit 30 supplies the optimum sound speed value to the phasing adder 44 in accordance with an instruction from the control unit 36.

The image analysis unit 26 is a part that compares two B-mode image data (ultrasound image data) and calculates an image variation amount.
Specifically, the image analysis unit 26 reads the latest B-mode image data and the B-mode image data of the previous frame from the image memory 52, and the difference between the luminance values of the two B-mode image data for each pixel ( (Absolute value) is obtained, and the total value of the differences of all pixels is calculated as the image fluctuation amount.

Here, the image analysis unit 26 may apply a low-pass filter to each B-mode image data before obtaining the difference between the two B-mode image data. The noise effect can be reduced by applying a low-pass filter to the B-mode image data before obtaining the difference. In addition, it is possible to detect the large movement (variation) as the image fluctuation amount by reducing the influence of the small movement (variation) of the ultrasonic probe.
Note that the low-pass filter may be any filter that can reduce the high-frequency component of the spatial frequency of the B-mode image data. Various known filters such as an averaging filter for setting the luminance value of the pixel to be used can be used.

  In the illustrated example of the image analysis unit 26, the difference is obtained for all the pixels of the two B-mode image data. However, the present invention is not limited to this, and the difference is obtained for some pixels to obtain the image fluctuation amount. It is good also as a structure. For example, when a region of interest is set, a difference may be obtained for pixels in the region of interest, and the total value of the differences may be used as the image fluctuation amount.

In the illustrated image analysis unit 26, the latest B-mode image data is compared with the B-mode image data of one frame before, and the image fluctuation amount is calculated. However, the present invention is not limited to this. Not done.
For example, the image analysis unit may be configured to calculate the amount of image fluctuation by comparing the latest B-mode image data with B-mode image data created before a predetermined frame from the B-mode image data.
Alternatively, the latest B-mode image data may be compared with B-mode image data generated from element data used when the previous sound velocity value was updated, and the image fluctuation amount may be calculated. Thereby, for example, when the ultrasonic probe is moved slowly, the optimum sound speed value can be appropriately updated even when the fluctuation is small with respect to the previous frame.

In the illustrated example, the image analysis unit 26 is configured to calculate the amount of image fluctuation by comparing two B-mode image data. However, the present invention is not limited to this, and a plurality of B-mode image data is compared. It may be configured to calculate the image fluctuation amount.
For example, a total value of differences between the latest B-mode image data and the B-mode image data of 1 to 3 frames before may be obtained, and an average value of the total values of the differences may be calculated as the image fluctuation amount.
The image analysis unit 26 supplies the calculated image fluctuation amount to the update necessity determination unit 28.

The update necessity determination unit 28 determines whether or not the image fluctuation amount supplied from the image analysis unit 26 is larger than a predetermined threshold, and determines whether or not the optimum sound speed value is updated by the sound speed determination unit 24. It is a part.
Specifically, the update necessity determination unit 28 determines the optimum sound speed value by the sound speed determination unit 24 when the image fluctuation amount supplied from the image analysis unit 26 changes from a predetermined threshold value or less to a value larger than the predetermined threshold value. It is determined that the update will be performed.

With reference to FIG. 3, the determination as to whether or not to update the sound speed in the necessity determination unit 28 will be described in detail.
In FIG. 3, the vertical axis represents the magnitude of the image fluctuation amount, and the horizontal axis represents the number of frames. A predetermined threshold value to be compared with the image fluctuation amount is indicated by a broken line. Also, below the horizontal axis, the type of transmission in the frame is shown. A case where transmission for acquiring B-mode image data (transmission according to the pattern for B mode) is performed is represented by B, and a case where transmission for sound speed update (transmission according to the pattern for sound speed update) is performed is represented by S. .

The update necessity determination unit 28 determines that the optimum sound speed value is not updated by the sound speed determination unit 24 when the image fluctuation amount supplied from the image analysis unit 26 is equal to or less than a predetermined threshold (frames 1 to 5). 11, 12).
On the other hand, the update necessity determination unit 28 determines the optimum sound speed value by the sound speed determination unit 24 in the next frame when the image variation amount is greater than or equal to a predetermined threshold value (frame 6 and frame 13). Determine to update.
Further, the update necessity determination unit 28 determines that the optimum sound speed value is not updated by the sound speed determination unit 24 when the image variation amount is larger than a predetermined threshold (frames 8 to 10 and frame 15). ~ 25).
The update necessity determination unit 28 supplies the determination result to the sound speed determination unit 24 and the transmission circuit 14.

As described above, the accuracy of the ultrasonic image is improved by measuring the optimal sound velocity value and generating the ultrasonic image based on the optimal sound velocity value. However, since the calculation load for calculating the optimum sound speed value is large, calculating the optimum sound speed value at every frame or at a short frame interval increases the calculation load, and the real-time property of displaying an ultrasonic image is poor. There was a problem of becoming.
If the interval for calculating the optimum sound speed value is lengthened, the calculation load is reduced and the real-time property of the ultrasonic image display can be prevented from being lowered. However, if the interval of calculation of the sound velocity value is increased, for example, when the observation position is changed by moving the ultrasonic probe, or when the observation position is searched, for example, when a fast-moving organ such as the heart is to be observed Therefore, there is a difference between the calculated sound speed value and the optimum sound speed value at the actually observed position, and even if an image is generated using the calculated sound speed value, a high-quality image can be obtained. There was a problem that I could not.

  On the other hand, the present invention calculates an image fluctuation amount between a plurality of ultrasonic image data generated at different timings, determines whether the image fluctuation amount is larger than a predetermined threshold, and determines the image fluctuation amount. When the value is larger than a predetermined threshold, the optimum sound speed value is updated. By calculating the image fluctuation amount, it is possible to detect whether the ultrasonic probe is moving or whether the observation target is moving. When the image fluctuation amount is larger than a predetermined threshold, by updating the optimum sound speed value, the sound speed value used for generating the ultrasonic image and the optimum sound speed value at the actually observed position are obtained. The optimum sound speed value can be updated at the timing when the deviation occurs. Therefore, even when the observation position is changed by moving the ultrasonic probe, or when the observation position is being searched for or when a fast-moving organ is the observation target, the optimum sound speed value is prevented while preventing an increase in the calculation load. Can be updated at an appropriate timing. Therefore, it is possible to always generate an ultrasonic image with an optimum sound velocity value suitable for an observation target, and to obtain a high-quality image.

  The predetermined threshold value for determining the image fluctuation amount is not particularly limited, and depends on the size of the B-mode image data, the observation target, the processing capability of the ultrasonic inspection apparatus, the required image quality, and the like. It may be determined as appropriate.

  Further, the update necessity determination unit 28 in the illustrated example determines that the optimum sound speed value is updated by the sound speed determination unit 24 when the image variation amount changes from a predetermined threshold value or less to a value greater than the predetermined threshold value. However, the present invention is not limited to this, and is a configuration in which it is determined that the sound speed determination unit 24 always updates the optimum sound speed value when the image fluctuation amount is a value larger than a predetermined threshold value. May be.

FIG. 4 shows a graph for explaining the necessity determination of the sound speed update in another example of the update necessity determination unit.
In FIG. 4, the vertical axis represents the amount of image fluctuation, and the horizontal axis represents the number of frames. A predetermined threshold value to be compared with the image fluctuation amount is indicated by a broken line. Also, below the horizontal axis, the type of transmission in the frame is shown. A case where transmission for acquiring B-mode image data (transmission according to the pattern for B mode) is performed is represented by B, and a case where transmission for sound speed update (transmission according to the pattern for sound speed update) is performed is represented by S. .

  The update necessity determination unit determines that the optimum sound speed value is updated by the sound speed determination unit 24 in the next frame when the image fluctuation amount is larger than a predetermined threshold (frames 6 to 10 and frames 13 to 25). To do.

  Further, the update necessity determination unit 28 in the illustrated example is configured to compare the image variation amount with one threshold value, but the present invention is not limited to this, and the image variation amount is between the two threshold values. When it enters, it is good also as a structure judged to update the optimal sound speed value by the sound speed determination part 24. FIG.

FIG. 5 shows a graph for explaining determination of necessity of sound speed update in another example of the necessity determination unit for update.
In FIG. 5, the vertical axis represents the magnitude of the image fluctuation amount, and the horizontal axis represents the number of frames. In addition, a predetermined first threshold value and a second threshold value to be compared with the image fluctuation amount are indicated by broken lines. Also, below the horizontal axis, the type of transmission in the frame is shown. A case where transmission for acquiring B-mode image data (transmission according to the pattern for B mode) is performed is represented by B, and a case where transmission for sound speed update (transmission according to the pattern for sound speed update) is performed is represented by S. .

The update necessity determination unit, when the image fluctuation amount changes to a value larger than the predetermined first threshold value and smaller than the predetermined second threshold value (frame 6, frame 13), It is determined that the optimum sound speed value is updated by the determination unit 24.
In the example shown in FIG. 5, the optimum sound speed value is determined to be updated at a timing when the image fluctuation amount changes to a value between the first threshold value and the second threshold value. The configuration is not limited, and the optimum sound speed value may always be updated when the image fluctuation amount is greater than the first threshold value and less than or equal to the second threshold value.

The control unit 36 controls each part of the ultrasonic examination apparatus based on a command input from the operation unit 38 by the operator.
Here, the control unit 36 provides various information by the operator via the operation unit 38, particularly information necessary for determining the optimum sound speed value by the sound speed determination unit 24, and image fluctuation by the image analysis unit 26. When the information necessary for calculating the quantity and the information necessary for determining whether or not the sound speed needs to be updated are input by the update necessity determination unit 28, the above-described various kinds of information input from the operation unit 38 are input. Information is supplied to each unit such as a transmission circuit 14, a reception circuit 16, an image generation unit 18, a reception signal storage unit 22, a sound speed determination unit 24, an image analysis unit 26, and an update necessity determination unit 28 as necessary.

  The operation unit 38 is for an operator to perform an input operation, and can be formed from a keyboard, a mouse, a trackball, a touch panel, or the like.

The storage unit 40 stores various information input from the operation unit 38, information necessary for processing and operation of each unit controlled by the control unit 36, and an operation program for executing processing and operation of each unit. A storage medium such as a hard disk, flexible disk, MO, MT, RAM, CD-ROM, DVD-ROM, SD card, CF card, or USB memory, or a server can be used.
Note that the phasing addition unit 44, the detection processing unit 46, the DSC 48, the image processing unit 50, the display control unit 32, the sound speed determination unit 24, the image analysis unit 26, and the update necessity determination unit 28 are a CPU and a CPU. The program is composed of operation programs for performing processing, but may be configured by a digital circuit.

Next, the operation of the first embodiment will be described.
When the operator abuts the ultrasonic probe 12 on the surface of the subject and starts measurement, ultrasonic waves are transmitted from the plurality of ultrasonic transducers of the transducer array 42 according to the drive signal supplied from the transmission circuit 14, Analog element signals are output from the ultrasonic transducers that have received ultrasonic echoes from the specimen to the reception circuit 16, element data is generated by the reception circuit 16, and sequentially stored in the reception signal storage unit 22.

  The phasing addition unit 44 of the image generation unit 18 reads the element data output from the reception circuit 16 or the element data temporarily stored in the reception signal storage unit 22. The phasing addition unit 44 performs delay correction based on the sound speed value stored in the sound speed storage unit 30 and adds the read element data to generate a sound ray signal. The detection processing unit 46 of the image generation unit 18 performs attenuation correction and envelope detection processing on the sound ray signal to generate B-mode image data.

  The B-mode image data is raster-converted by the DSC 48, subjected to various image processing by the image processing unit 50, supplied to the display control unit 32, and used for display on the display unit 34. Thereby, an ultrasonic image is displayed on the display unit 34 in real time. The B-mode image data is stored in the image memory 52.

  Further, the image analysis unit 26 reads the latest B-mode image data stored in the image memory 52 and the B-mode image data of the previous frame, and calculates the image fluctuation amount. The update necessity determination unit 28 determines whether or not the image fluctuation amount is larger than a predetermined threshold value. When the image fluctuation amount is larger than the predetermined threshold value, a signal indicating that the optimum sound speed value is updated is transmitted as the sound speed value. The data is supplied to the determination unit 24 and the transmission circuit 14.

  When a signal to update the sonic velocity is supplied from the update necessity determination unit 28, the transmission circuit 14 transmits an ultrasonic beam according to the sonic velocity update pattern. The element data output from the reception circuit 16 upon receiving the ultrasonic echo is stored in the reception signal storage unit 22. Further, the sound speed determination unit 24 supplies a predetermined plurality of set sound speeds to the phasing addition unit 44. The phasing addition unit 44 reads out element data from the reception signal storage unit 22 based on the set sound speed V supplied from the sound speed determination unit 24 and performs reception focus processing to generate a sound ray signal. The image generator 18 generates new B-mode image data from the sound ray signal and supplies it to the image memory 52. The image generation unit 18 similarly generates B-mode image data at each of a plurality of set sound velocities V, and supplies each B-mode image data to the image memory 52.

  The sound speed determination unit 24 calculates the contrast or sharpness of the plurality of B-mode image data generated based on the plurality of set sound speeds V for each predetermined area, and sets the set sound speed V that provides the highest contrast or sharpness in the area. The optimum sound speed is determined, and the optimum sound speed value stored in the sound speed storage unit 30 is updated using the information on the optimum sound speed in each region as the sound speed map.

  Thus, the present invention calculates the amount of image fluctuation between a plurality of ultrasonic image data generated at different timings, determines whether or not the amount of image fluctuation is greater than a predetermined threshold, and the amount of image fluctuation is When the value is larger than the predetermined threshold, the optimum sound speed value is updated. By calculating the image fluctuation amount, it is possible to detect whether the ultrasonic probe is moving or whether the observation target is moving. When the image fluctuation amount is larger than a predetermined threshold, by updating the optimum sound speed value, the sound speed value used for generating the ultrasonic image and the optimum sound speed value at the actually observed position are obtained. The optimum sound speed value can be updated at the timing when the deviation occurs. Therefore, even when the observation position is changed by moving the ultrasonic probe, or when the observation position is being searched for or when a fast-moving organ is the observation target, the optimum sound speed value is prevented while preventing an increase in the calculation load. Can be updated at an appropriate timing. Therefore, it is possible to always generate an ultrasonic image with an optimum sound velocity value suitable for an observation target, and to obtain a high-quality image.

  When transmission is performed using a sound speed update pattern in order to update the optimum sound speed value, the element data obtained by this transmission is subjected to reception focus processing using the optimum sound speed value before update. The B-mode image data may be generated by performing the reception focusing process using the updated optimum sound speed value. In the case of performing reception focus processing using the updated optimum sound speed value, the element data is stored in the reception signal storage unit 22 and the optimum sound speed value is stored using the element data stored after the update of the optimum sound speed value. A B-mode image may be generated based on the above.

  In the first embodiment, the calculated optimum sound speed value is used for generating B-mode image data in the next frame. However, the present invention is not limited to this, and in parallel with the calculation of the optimum sound speed value, A configuration may be adopted in which generation of B-mode image data at the optimum sound speed value is continued and displayed on the display unit 34, and the new optimum sound speed value is used at the timing when the optimum sound speed value is updated.

  In the first embodiment, the sound speed determination unit 24 updates the optimum sound speed value when the update necessity determination unit 28 determines the image fluctuation amount and determines that the update is necessary. In addition, the optimum sound speed value may be updated when a predetermined frame has elapsed since the previous update.

  In the first embodiment, it is determined whether the entire image (scanning range) needs to be updated and the optimum sound velocity value is updated. However, the present invention is not limited to this, and a part of the image is displayed. It may be possible to determine whether or not the update is necessary using only the image, or to update the sound speed only for a part of the image.

  For example, when the region of interest (ROI) is set in the image as shown in FIG. 6A, when the sound speed is updated, the transmission line corresponding to the region of interest as shown in FIG. A configuration may be adopted in which ultrasonic waves are transmitted and received according to a sound speed update pattern in which the number of transmission focal points is increased, and the optimum sound speed value in the region of interest is updated.

Note that the region of interest ROI may be arbitrarily set by the operator, or may be automatically selected by image analysis.
In the illustrated example, the transmission focus is increased on the transmission line corresponding to the region of interest. However, the configuration is not limited to this, and the transmission focal point in the region of interest may be increased.
Further, the frequency of sound speed update in a region other than the region of interest may be less than the frequency of sound speed update in the region of interest.

  In the first embodiment, the transmission / reception of ultrasonic waves for sound speed update is performed in one frame, that is, the sound speed update pattern is configured to support transmission / reception for one frame. However, the present invention is not limited to this, and the sound speed update pattern may be divided, and the sound speed update pattern may be partially transmitted / received over a plurality of frames to perform transmission / reception corresponding to one frame.

FIGS. 7A to 7D are diagrams conceptually showing transmission focus arrangement patterns each including a part of the sound velocity update pattern.
In the arrangement pattern shown in FIG. 7A, only the leftmost transmission line in the drawing is a sonic update pattern, and the other transmission lines are B-mode patterns. In the arrangement pattern shown in FIG. 7B, the second transmission line from the left is used as a sound speed update pattern. In the arrangement pattern shown in FIG. 7C, the third transmission line from the left is used as the sound speed update pattern. In the arrangement pattern shown in FIG. 7D, the fourth transmission line from the left is used as the sound speed update pattern.

  When the update necessity determination unit 28 determines the update of the optimum sound speed value, ultrasonic waves are sequentially transmitted and received in the arrangement patterns shown in FIGS. 7A to 7D to update the sound speed of each arrangement pattern. The element data obtained by transmission / reception is stored in the reception signal storage unit 22 as element data for sound velocity update. The sound speed determination unit determines the optimum sound speed value using B-mode image data generated using the stored element data.

  As described above, the ultrasonic inspection apparatus of the present invention, the signal processing method of the ultrasonic inspection apparatus, and the program have been described in detail, but the present invention is not limited to the above examples, and in a range not departing from the gist of the present invention. Of course, various improvements and modifications may be made.

  The signal processing program is not limited to the one stored in the memory attached to the control unit, and the signal processing program is a memory medium (for example, a CD-ROM) that is detachably attached to the ultrasonic inspection apparatus ( The information may be recorded on a removable medium and read into the apparatus via an interface corresponding to the removable medium.

DESCRIPTION OF SYMBOLS 10 Ultrasonic inspection apparatus 12 Ultrasonic probe 14 Transmission circuit 16 Reception circuit 18 Image generation part 22 Received signal storage part 24 Sonic speed determination part 26 Image analysis part 28 Update necessity judgment part 30 Sonic speed storage part 32 Display control part 34 Display part 36 Control unit 38 Operation unit 40 Storage unit 42 Transducer array 44 Phased addition unit 46 Detection processing unit 48 DSC
50 Image processor 52 Image memory

Claims (8)

An ultrasonic inspection apparatus that inspects an inspection object using an ultrasonic beam,
A transducer array in which a plurality of elements are arranged to transmit the ultrasonic beam, receive an ultrasonic echo reflected by the inspection object, and output an element signal corresponding to the received ultrasonic echo When,
A transmitter for transmitting the ultrasonic beam to the transducer array using a plurality of the elements;
A receiving unit that performs a predetermined process on the element signal that the plurality of elements of the transducer array receive and output an ultrasonic echo and outputs the element signal; and
A reception signal storage unit for storing the element data output by the reception unit;
An image generation unit that generates a sound ray signal by phasing and adding the element data based on a predetermined sound velocity value, and generating ultrasonic image data from the sound ray signal;
An image memory for storing the ultrasonic image data generated by the image generation unit;
An image analysis unit that calculates an image variation amount between a plurality of ultrasonic image data generated at different timings;
An optimum sound speed value is determined from a plurality of ultrasonic image data generated by the image generation unit based on a plurality of predetermined set sound speeds using the element data stored in the reception signal storage unit, and an optimum sound speed is determined. A sound speed determination unit for updating the value;
It is determined whether or not the image fluctuation amount calculated by the image analysis unit is larger than a predetermined threshold value. When the image fluctuation amount is larger than the predetermined threshold value, the sound speed determination unit determines the optimum sound speed value. An ultrasonic inspection apparatus comprising: an update necessity determination unit that determines to perform determination and update.   2. The update necessity determination unit according to claim 1, wherein when the image fluctuation amount changes from a value equal to or less than the predetermined threshold value to a value larger than the predetermined threshold value, it is determined that the optimum sound speed value needs to be updated. Ultrasonic inspection equipment.   When the update necessity determination unit determines that the optimum sound speed value needs to be updated, the transmission unit causes the transducer array to transmit an ultrasonic beam for sound speed update, and the sound speed determination unit The ultrasonic inspection apparatus according to claim 1, wherein an optimum sound velocity value is determined using the element data obtained by transmitting the ultrasonic beam for updating the sound velocity, and the optimum sound velocity value is updated.   The said image analysis part calculates the said image variation | change_quantity between the newest ultrasonic image data and the ultrasonic image data acquired before this newest ultrasonic image data predetermined frame. 4. The ultrasonic inspection apparatus according to any one of 3.   The image analysis unit calculates the image fluctuation amount between the latest ultrasonic image data and the ultrasonic image data generated using the element data when the optimum sound speed value is updated. The ultrasonic inspection apparatus according to claim 1.   The update necessity determination unit determines that the optimum sound speed value needs to be updated when the image fluctuation amount is larger than a predetermined first threshold and smaller than a second threshold larger than the first threshold. The ultrasonic inspection apparatus according to any one of claims 1 to 5. A transducer array in which a plurality of elements are arranged, which transmits an ultrasonic beam, receives an ultrasonic echo reflected in the inspection object, and outputs an element signal corresponding to the received ultrasonic echo. , A signal processing method of an ultrasonic inspection apparatus for generating the ultrasonic beam, inspecting the inspection object, and generating ultrasonic image data,
A transmission step of causing the transducer array to transmit the ultrasonic beam using a plurality of the elements;
A receiving step of performing a predetermined process on the element signal output by the plurality of elements of the transducer array receiving and outputting ultrasonic echoes;
A received signal storing step for storing the element data output by the receiving step;
An image generation step of generating a sound ray signal by phasing and adding the element data based on a predetermined sound velocity value, and generating ultrasonic image data from the sound ray signal;
An image storage step for storing the ultrasonic image data generated in the image generation step;
An image analysis step for calculating an image variation amount between a plurality of ultrasonic image data generated at different timings;
An optimum sound speed value is determined from a plurality of ultrasonic image data generated in the image generation step based on a plurality of predetermined set sound speeds using the element data stored in the received signal storage step, and an optimum sound speed is determined. A sound velocity determination step for updating the value;
It is determined whether or not the image fluctuation amount calculated in the image analysis step is larger than a predetermined threshold value. When the image fluctuation amount is larger than the predetermined threshold value, the optimum sound speed value of the sound speed determination step is determined. A signal processing method for an ultrasonic inspection apparatus, comprising: an update necessity determination step for determining whether to perform determination and update. A transducer array in which a plurality of elements are arranged, which transmits an ultrasonic beam, receives an ultrasonic echo reflected in the inspection object, and outputs an element signal corresponding to the received ultrasonic echo. A program for causing a computer to execute a signal processing method of an ultrasonic inspection apparatus that generates the ultrasonic beam, inspects the inspection object, and generates ultrasonic image data,
A transmission step of causing the transducer array to transmit the ultrasonic beam using a plurality of the elements;
A receiving step of performing a predetermined process on the element signal output by the plurality of elements of the transducer array receiving and outputting ultrasonic echoes;
A received signal storing step for storing the element data output by the receiving step;
An image generation step of generating a sound ray signal by phasing and adding the element data based on a predetermined sound velocity value, and generating ultrasonic image data from the sound ray signal;
An image storage step for storing the ultrasonic image data generated in the image generation step;
An image analysis step for calculating an image variation amount between a plurality of ultrasonic image data generated at different timings;
An optimum sound speed value is determined from a plurality of ultrasonic image data generated in the image generation step based on a plurality of predetermined set sound speeds using the element data stored in the received signal storage step, and an optimum sound speed is determined. A sound velocity determination step for updating the value;
It is determined whether or not the image fluctuation amount calculated in the image analysis step is larger than a predetermined threshold value. When the image fluctuation amount is larger than the predetermined threshold value, the optimum sound speed value of the sound speed determination step is determined. A signal processing program for an ultrasonic inspection apparatus, which causes a computer to execute an update necessity determination step for determining whether to perform determination and update.

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