JP2020039821A - Ultrasound wave observation apparatus, ultrasound wave observation apparatus operation method, and ultrasound wave observation apparatus operation program - Google Patents

Abstract

To provide an ultrasound wave observation apparatus that allows observation at high luminance without the contrast medium being destroyed.SOLUTION: The ultrasound wave observation apparatus transmits an ultrasound wave to a subject to which a contrast medium has been administered and generates an ultrasound image on the basis of ultrasound signals reflected by the contrast medium, the ultrasound wave observation apparatus comprising: an average luminance value calculation unit for calculating an average luminance value in a predetermined region, for each of a plurality of ultrasound images generated by transmitting an ultrasound wave at a constant sound pressure; a limit value calculation unit for calculating a limit value of the sound pressure of the ultrasound wave in which the contrast medium is not destroyed, based on the amount of variation in the average luminance value; and a control unit for control to limit the sound pressure of the transmitted ultrasound wave to the limit value or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic observation apparatus, an operation method of the ultrasonic observation apparatus, and an operation program of the ultrasonic observation apparatus.

  2. Description of the Related Art Conventionally, there has been known an ultrasonic observation apparatus that transmits and receives an ultrasonic wave to and from a subject to generate an ultrasonic image. When performing ultrasonic observation, a contrast agent for ultrasonic waves, which is a suspension of microbubbles, may be used (for example, see Patent Document 1). The contrast agent is administered to the subject, and the microbubbles vibrate, resonate, or collapse due to the ultrasound while moving by the blood flow or the like in the subject, so the position where the contrast agent is present in the ultrasound image has brightness. Get higher.

  When a contrast agent is used, when the sound pressure of the ultrasonic wave is low, the contrast agent vibrates or resonates due to the ultrasonic wave, and the sound pressure of the ultrasonic wave and the luminance of the ultrasonic image are substantially proportional to each other. However, when the sound pressure of the ultrasonic wave increases and exceeds the destructive sound pressure at which the microbubbles of the contrast agent are destroyed, the microbubbles of the contrast agent are destroyed and reduced, so that the brightness sharply decreases. Therefore, in the ultrasonic observation using the contrast agent, it is preferable to perform the observation at a sound pressure as high as possible within a range not exceeding the destructive sound pressure. However, since the contrast agent moves in the subject, it is very difficult to transmit an ultrasonic wave having an appropriate sound pressure according to the position where the contrast agent exists. Patent Literature 1 discloses that a destructive sound pressure can be detected by obtaining a luminance change curve while changing a sound pressure with time.

JP 2009-5755 A

  However, in the technique of Patent Document 1, since the sound pressure is changed over time, the brightness value cannot be detected stably due to the influence of the change over time of the brightness caused by the inflow or outflow of the contrast agent. Therefore, the destructive sound pressure cannot be accurately obtained from the detected luminance value. Therefore, when adjusting the sound pressure of the ultrasonic wave using the technique of Patent Document 1, the sound pressure is set too high and the contrast agent is destroyed, or the brightness is reduced by reducing the sound pressure more than necessary. In some cases.

  The present invention has been made in view of the above, the contrast agent is not destroyed, and an ultrasonic observation device capable of observing with high luminance, an operation method of the ultrasonic observation device, and an ultrasonic observation device It is intended to provide an operating program.

  In order to solve the above-described problem and achieve the object, an ultrasonic observation apparatus according to one embodiment of the present invention transmits an ultrasonic wave to a subject to which a contrast agent has been administered, and is reflected by the contrast agent. An ultrasonic observation apparatus that generates an ultrasonic image based on the generated ultrasonic signal, wherein a predetermined area is defined for each of the plurality of ultrasonic images generated by transmitting ultrasonic waves at a constant sound pressure. An average brightness value calculation unit that calculates an average brightness value within the range, a limit value calculation unit that calculates a limit value of the sound pressure of an ultrasonic wave that does not destroy the contrast agent based on the amount of change in the average brightness value, and transmission. A control unit that controls the sound pressure of the ultrasonic wave to be controlled to be equal to or less than the limit value.

  Further, the ultrasonic observation apparatus according to one aspect of the present invention is characterized in that the limit value calculation unit calculates the limit value based on an approximate curve calculated from a temporal change of the average luminance value. .

  Further, in the ultrasonic observation apparatus according to an aspect of the present invention, the predetermined region includes a center of the ultrasonic image.

  Further, in the ultrasonic observation apparatus according to one aspect of the present invention, the limit value calculating unit changes the sound pressure of the transmitted ultrasonic wave from a low sound pressure to a high sound pressure, and calculates the average calculated at each sound pressure. The limit value is calculated based on a change amount of the luminance value.

  Further, in the ultrasonic observation apparatus according to one aspect of the present invention, the limit value calculation unit may be configured such that a relationship between a feature amount calculated based on a change amount of the average luminance value and a threshold satisfies a predetermined condition. In addition, the sound pressure of the ultrasonic wave transmitted immediately before the sound pressure of the ultrasonic wave transmitted when the condition is satisfied is calculated as the limit value.

  Further, in the ultrasonic observation apparatus according to one aspect of the present invention, the plurality of ultrasonic images are captured in a state where a frame rate is constant, and the limit value calculation unit calculates the limit value according to the frame rate. It is characterized in that it is calculated.

  Further, the operation method of the ultrasonic observation apparatus according to one embodiment of the present invention transmits an ultrasonic wave to a subject to which a contrast agent has been administered, and transmits an ultrasonic wave based on an ultrasonic signal reflected by the contrast agent. An operation method of an ultrasonic observation apparatus that generates an image, wherein the average luminance value calculation unit transmits a predetermined amount of ultrasonic waves at a constant sound pressure, and each of the plurality of ultrasonic images generated, a predetermined An average brightness value calculating step of calculating an average brightness value in the region, and a limit value calculating unit calculates a limit value of the sound pressure of the ultrasonic wave in which the contrast agent is not destroyed based on the change amount of the average brightness value. It is characterized by including a limit value calculating step and a control step of controlling the sound pressure of the transmitted ultrasonic wave to be limited to the limit value or less.

  In addition, the operation program of the ultrasonic observation apparatus according to one embodiment of the present invention transmits an ultrasonic wave to a subject to which a contrast agent has been administered, and transmits an ultrasonic wave based on an ultrasonic signal reflected by the contrast agent. An operation program of an ultrasonic observation apparatus that generates an image, wherein the average luminance value calculation unit transmits a predetermined amount of ultrasonic waves at a constant sound pressure, and for each of the plurality of ultrasonic images generated, a predetermined An average brightness value calculating step of calculating an average brightness value in the region, and a limit value calculating unit calculates a limit value of the sound pressure of the ultrasonic wave in which the contrast agent is not destroyed based on the change amount of the average brightness value. A limit value calculating step and a control step in which the control unit controls the sound pressure of the ultrasonic wave to be transmitted so as to limit the sound pressure to the limit value or less are executed by the ultrasonic observation apparatus.

  Advantageous Effects of Invention According to the present invention, it is possible to realize an ultrasonic observation apparatus, an operation method of the ultrasonic observation apparatus, and an operation program of the ultrasonic observation apparatus, which enable observation with high luminance without destroying a contrast agent.

FIG. 1 is a block diagram illustrating a configuration of an ultrasonic observation system including an ultrasonic observation device according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating an outline of a process performed by the ultrasonic observation apparatus according to the embodiment of the present invention. FIG. 3 is a flowchart showing an outline of the processing for calculating the sound pressure limit value in FIG. FIG. 4 is a diagram illustrating an example of an ultrasonic image. FIG. 5 is a diagram illustrating an example of a method for calculating an average luminance value. FIG. 6 is a diagram illustrating a relationship between sound pressure and luminance.

  Hereinafter, embodiments of an ultrasonic observation apparatus, an operation method of the ultrasonic observation apparatus, and an operation program of the ultrasonic observation apparatus according to the present invention will be described with reference to the drawings. The present invention is not limited by these embodiments. INDUSTRIAL APPLICABILITY The present invention can be generally applied to an ultrasonic observation apparatus equipped with a contrast mode, an operation method of the ultrasonic observation apparatus, and an operation program of the ultrasonic observation apparatus.

  In the drawings, the same or corresponding elements are denoted by the same reference numerals as appropriate. In addition, it is necessary to keep in mind that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may be different from reality. Even in the drawings, there may be cases where portions having different dimensional relationships and ratios are included.

(Embodiment)
FIG. 1 is a block diagram illustrating a configuration of an ultrasonic observation system including an ultrasonic observation device according to an embodiment of the present invention. The ultrasonic observation system 1 transmits an ultrasonic wave to an object to be observed, receives an ultrasonic wave reflected by the object, and an ultrasonic probe 2 based on an ultrasonic signal acquired by the ultrasonic probe 2. An ultrasonic observation device 3 that generates an ultrasonic image by using the ultrasonic observation device 3 and a display device 4 that displays the ultrasonic image generated by the ultrasonic observation device 3 are provided. The ultrasonic observation apparatus 3 includes, as observation modes of the ultrasonic wave, a B mode in which the amplitude of the echo signal is converted into luminance to generate an image, and an ultrasonic observation mode, which is a suspension of microbubbles introduced into the subject. This is an ultrasonic observation apparatus capable of selecting a contrast mode for generating an image in which a contrast agent is emphasized and displayed. In the contrast agent mode, the ultrasonic observation device 3 transmits an ultrasonic wave to the subject to which the contrast agent has been administered, and generates an ultrasonic image based on the ultrasonic signal reflected by the contrast agent.

  The ultrasonic probe 2 converts the electric pulse signal received from the ultrasonic observation device 3 into an ultrasonic pulse (acoustic pulse) at the tip thereof, irradiates the ultrasonic wave to the subject, and reflects the ultrasonic wave reflected by the subject. This is an endoscope having an ultrasonic transducer 21 that converts an acoustic echo into an electrical echo signal (ultrasonic signal) that is represented by a voltage change and outputs the signal. The ultrasonic transducer 21 is realized by a transducer of a convex type, a linear type, a radial type, or the like. The ultrasonic probe 2 may be one that mechanically scans the ultrasonic transducer 21, or a plurality of elements that are arranged in an array as the ultrasonic transducer 21, and elements that are involved in transmission and reception are electronically switched. Alternatively, electronic scanning may be performed by delaying transmission and reception of each element.

  The ultrasound probe 2 usually has an imaging optical system and an imaging device, and is inserted into a digestive tract (esophagus, stomach, duodenum, large intestine) or a respiratory organ (trachea, bronchi) of the subject, and It is possible to image the respiratory organ and its surrounding organs (pancreas, gallbladder, bile duct, biliary tract, lymph nodes, mediastinal organs, blood vessels, etc.). Further, the ultrasonic probe 2 has a light guide for guiding illumination light to irradiate the subject during imaging. The light guide has a distal end reaching the distal end of the insertion portion of the ultrasonic probe 2 into the subject, and a proximal end connected to a light source device for generating illumination light.

  The ultrasonic observation apparatus 3 includes a transmission unit 31, a reception unit 32, a signal processing unit 33, an image generation unit 34, an average luminance value calculation unit 35, a limit value calculation unit 36, an input unit 37, And a storage unit 39.

  The transmission unit 31 is electrically connected to the ultrasonic probe 2 and transmits a transmission signal (pulse signal) including a high-voltage pulse to the ultrasonic transducer 21 based on a predetermined waveform and transmission timing. The frequency band of the pulse signal transmitted by the transmission unit 31 is preferably set to a wide band that almost covers the linear response frequency band of the electroacoustic conversion of the pulse signal into the ultrasonic pulse in the ultrasonic transducer 21. Further, the transmission unit 31 transmits various control signals output from the control unit 38 to the ultrasonic probe 2.

  The receiving unit 32 receives an echo signal, which is an electrical reception signal, from the ultrasonic transducer 21, and performs A / D conversion on the received echo signal to obtain data of a digital high frequency (RF) signal (hereinafter, referred to as RF data). ) Is generated and output. Further, the receiving unit 32 has a function of receiving various information including the ID for identification from the ultrasonic probe 2 and transmitting the information to the control unit 38.

  The signal processing unit 33 generates digital B-mode reception data based on the RF data received from the reception unit 32. Specifically, the signal processing unit 33 performs known processing such as band-pass filtering, envelope detection, and logarithmic conversion on the RF data to generate digital B-mode reception data. In the logarithmic conversion, a common logarithm of an amount obtained by dividing the RF data by the reference voltage Vc is expressed as a decibel value. The signal processing unit 33 outputs the generated B-mode reception data for one frame to the image generation unit 34. The signal processing unit 33 is realized using a CPU (Central Processing Unit), various arithmetic circuits, and the like.

  The image generation unit 34 generates image data based on the RF data received from the reception unit 32. The image generation unit 34 performs signal processing on the received data for B mode stored in the storage unit 39 using a known technique such as a scan converter process, a gain process, and a contrast process. B-mode image data is generated by thinning out data according to a data step width determined according to the display range of the image. In the scan converter process, the scan direction of the reception data for B mode is converted from the scan direction of the ultrasonic wave to the display direction of the display device 4. The B-mode image is a grayscale image in which the values of R (red), G (green), and B (blue), which are variables when the RGB color system is adopted as the color space, are matched.

  The image generation unit 34 performs a coordinate transformation for rearranging the B-mode reception data from the signal processing unit 33 so that the scanning range can be spatially correctly expressed, and then performs an interpolation process between the B-mode reception data. The B-mode image data is generated by filling the gap between the B-mode received data.

  The average luminance value calculation unit 35 calculates an average luminance value in a predetermined region for each of a plurality of ultrasonic images generated by transmitting ultrasonic waves at a constant sound pressure. The constant sound pressure means that the ultrasonic wave is transmitted with the MI (Mechanical Index) value, which is an index of the sound pressure of the ultrasonic wave transmitted from the ultrasonic probe 2 to the subject, kept constant.

  The limit value calculating unit 36 calculates a limit value of the sound pressure of the ultrasonic wave at which the contrast agent is not destroyed, based on the change amount of the average luminance value. Specifically, the limit value calculation unit 36 changes the sound pressure of the ultrasonic wave to be transmitted from a low sound pressure to a high sound pressure, and obtains an approximate curve derived from a time change of the average luminance value calculated at each sound pressure. When the condition that the inclination is equal to or less than the predetermined threshold is satisfied, the sound pressure transmitted immediately before the sound pressure of the ultrasonic wave transmitted at that time is calculated as a limit value. In other words, the limit value calculation unit 36 calculates, as the limit value, a sound pressure that is smaller by a predetermined value (for example, 0.1) than the destruction sound pressure at which the contrast agent is destroyed and the average luminance value sharply decreases.

  The input unit 37 receives a signal based on an input operation to a user interface such as a keyboard, a button, a mouse, a trackball, and a touch panel. The input unit 37 receives an instruction input by the user for instructing the start of the contrast mode and an instruction input for instructing the end of the contrast mode. Further, the input unit 37 has a sound pressure limit button for receiving an instruction input for limiting the sound pressure to a value equal to or less than the limit value calculated by the limit value calculation unit 36.

  The control unit 38 controls the entire ultrasonic observation system 1. Further, the control unit 38 controls the sound pressure of the ultrasonic wave transmitted from the ultrasonic transducer 21 to the subject to be limited to the limit value calculated by the limit value calculation unit 36 or less. The control unit 38 is realized using a CPU having arithmetic and control functions, various arithmetic circuits, and the like. The control unit 38 reads out information stored and stored in the storage unit 39 from the storage unit 39 and performs various arithmetic processes related to an operation method of the ultrasonic observation device 3 to control the ultrasonic observation device 3 in a centralized manner. I do. Note that the control unit 38 may be configured using a CPU or the like common to the signal processing unit 33, the image generation unit 34, the average luminance value calculation unit 35, and the limit value calculation unit 36.

  The storage unit 39 stores various programs for operating the ultrasonic observation system 1, data including various parameters necessary for the operation of the ultrasonic observation system 1, and the like. The storage unit 39 stores, for example, the correspondence between the depth observed by the ultrasonic transducer 21 and the pulse repetition frequency transmitted by the ultrasonic transducer 21 in each sound ray direction. Further, the storage unit 39 stores a negative sound pressure, which is sound pressure data at each sampling point on each sound ray of the ultrasonic signal acquired in advance. The negative sound pressure is obtained by driving the ultrasonic vibrator 21 in water, arranging an ultrasonic receiver at a sampling point on each sound ray of the ultrasonic signal, and measuring an echo signal.

  In addition, the storage unit 39 stores various programs including an operation program for executing the operation method of the ultrasonic observation system 1. The operation program can be recorded on a computer-readable recording medium such as a hard disk, a flash memory, a CD-ROM, a DVD-ROM, and a flexible disk, and widely distributed. Note that the various programs described above can also be obtained by downloading via a communication network. The communication network referred to here is realized by, for example, an existing public line network, a local area network (LAN), a wide area network (WAN), or the like, and may be wired or wireless.

  The storage unit 39 having the above configuration is realized using a ROM (Read Only Memory) in which various programs and the like are installed in advance, a RAM (Random Access Memory) that stores calculation parameters and data of each process, and the like. .

  The display device 4 receives and displays the data signal of the ultrasonic image generated by the ultrasonic observation device 3 via the video cable. The display device 4 is configured using a monitor such as a liquid crystal or an organic EL (Electro Luminescence).

  FIG. 2 is a flowchart illustrating an outline of a process performed by the ultrasonic observation apparatus according to the embodiment of the present invention. When the contrast mode is started, the control unit 38 determines whether the sound pressure restriction button has been pressed (step S1). Specifically, the control unit 38 determines whether the sound pressure restriction button of the input unit 37 has been pressed and a predetermined signal has been input.

  When the control unit 38 determines that the sound pressure restriction button has not been pressed (step S1: No), the ultrasound probe 2 transmits and receives ultrasound to and from the subject under the control of the ultrasound observation device 3. Then, the image generator 34 generates an ultrasonic image under the control of the controller 38 (Step S2). At this time, the MI value of the ultrasonic wave transmitted from the ultrasonic probe 2 to the subject is a value set by the user, and can be set to an arbitrary value.

  Thereafter, the control unit 38 determines whether or not an instruction to end the contrast mode has been input to the input unit 37 (step S3). When the control unit 38 determines that the instruction to end the contrast mode has been input to the input unit 37 (step S3: Yes), the ultrasonic observation apparatus 3 ends a series of processing. On the other hand, when the control unit 38 determines that the instruction to end the contrast mode has not been input to the input unit 37 (step S3: No), the process returns to step S1.

  In step S1, when the control unit 38 determines that the sound pressure restriction button has been pressed (step S1: Yes), the ultrasonic observation apparatus 3 calculates a limit value of the sound pressure (step S4).

  FIG. 3 is a flowchart showing an outline of the processing for calculating the sound pressure limit value in FIG. First, the control unit 38 sets the MI value to an initial value (for example, 0.1) (Step S11). However, the control unit 38 may set the MI value to a value sufficiently lower than the destruction sound pressure, and may set the initial value of the MI value to zero, for example.

  Subsequently, the ultrasonic probe 2 transmits an ultrasonic wave to the subject at the set sound pressure (0.1) under the control of the ultrasonic observation device 3 (Step S12).

  Then, the ultrasonic probe 2 and the ultrasonic observation device 3 repeatedly execute transmission and reception of the ultrasonic wave to acquire a predetermined number (N) of ultrasonic images (step S13). However, the predetermined number is not particularly limited, and a plurality of ultrasonic images may be obtained. Note that the frame rate is kept constant while acquiring a predetermined number of ultrasonic images.

  Thereafter, the average luminance value calculation unit 35 calculates an average luminance value in a predetermined region for each of the acquired ultrasonic images (Step S14). FIG. 4 is a diagram illustrating an example of an ultrasonic image. As shown in FIG. 4, the average luminance value calculation unit 35 calculates an average luminance value in a region A as a predetermined region including the center C of the ultrasonic image 5, for example. Usually, the user preferably sets a predetermined area so as to include the center C in order to display the observation target near the center C of the ultrasonic image 5. FIG. 4 illustrates the ultrasonic image 5 in the case of using the convex type ultrasonic oscillator 21 in which the ultrasonic oscillator 21 is located at the upper center of the image. However, the present invention is not limited to this. Further, the shape of the region A is not particularly limited.

  The limit value calculator 36 calculates an approximate curve based on the average luminance value (Step S15). FIG. 5 is a diagram illustrating an example of a method for calculating an average luminance value. In FIG. 5, the horizontal axis represents the frame numbers of a plurality of (N) ultrasound images arranged in time series that have been acquired. The smaller the frame number is, the more it corresponds to the ultrasonic image taken earlier in time. As shown in FIG. 5, the limit value calculating unit 36 arranges the average luminance values of the ultrasonic images 5 of the respective frames (F1, F2,..., FN) in the order in which they were captured, and based on the arranged points. Calculate the approximate curve.

  Further, the limit value calculating unit 36 determines whether or not the calculated slope of the approximate curve is equal to or smaller than a threshold (Step S16). The threshold value is a negative value, which will be described later. When the limit value calculating unit 36 determines that the calculated slope of the approximate curve is not equal to or smaller than the threshold value (step S16: No), the control unit 38 increases the MI value by a predetermined value (for example, 0.02) and sets the MI value to 0.0. It is set to 12 (step S17). Thereafter, the process returns to step S12, and the process is continued. Note that the limit value calculation unit 36 may compare the average value of the slope of the approximate curve with a threshold, or may compare the maximum value of the slope of the approximate curve with the threshold.

  On the other hand, when the limit value calculation unit 36 determines that the calculated slope of the approximate curve is equal to or smaller than the threshold value (step S16: Yes), the limit value calculation unit 36 determines the MI value immediately before the current MI value as the sound pressure. (Step S18). Specifically, for example, in a state where the MI value is set to 0.16, when the limit value calculating unit 36 determines that the calculated slope of the approximate curve is equal to or less than the threshold, the limit value calculating unit 36 The MI value (0.14) immediately before the current MI value (0.16) is calculated as the sound pressure limit value.

  FIG. 6 is a diagram illustrating a relationship between sound pressure and luminance. FIG. 6 shows a temporal change of a luminance value when the ultrasonic image 5 is continuously generated at a constant sound pressure and a constant frame rate for a long time. In FIG. 6, the sound pressure of the ultrasonic waves transmitted in the order of the line L1, the line L2, and the line L3 is changed from a low pressure to a high pressure.

  As shown in FIG. 6, in the lines LI and L2 where the sound pressure of the ultrasonic waves is small, the microbubbles vibrate or resonate due to the ultrasonic waves. Therefore, the sound pressure of the ultrasonic waves and the luminance of the ultrasonic image 5 are substantially proportional to each other. And the larger the MI value, the higher the luminance. On the other hand, in the line L3 where the sound pressure of the ultrasonic wave is high, the sound pressure of the ultrasonic wave exceeds the destruction sound pressure at which the minute bubbles of the contrast agent are destroyed, and the minute bubbles of the contrast agent are destroyed and reduced. Therefore, the brightness rapidly decreases. To determine whether the ultrasonic sound pressure exceeds the destructive sound pressure, an ultrasonic image 5 is generated at a constant sound pressure and a constant frame rate for a very short time (for example, about several seconds), and the average luminance value is determined. What is necessary is just to judge whether it decreases rapidly. In other words, it is determined whether or not the slope of the approximate curve representing the time change of the average luminance value is equal to or less than the negative threshold value (that is, whether the luminance sharply decreases). Can be determined. Specifically, in FIG. 6, it is determined whether or not the slope A1 (overlapping with the line L1 in FIG. 6), the slope A2, and the slope A3 in the lines L1, L2, and L3 up to the frame number n are equal to or smaller than the threshold. do it. In the line L3, since the luminance sharply decreases during the period of acquiring the ultrasonic images from the frame numbers 0 to n, the gradient A3 is equal to or less than the threshold, and the sound pressure exceeds the sound pressure at which the contrast agent is destroyed. I understand. That is, in FIG. 6, the contrast agent moves at a sufficiently low speed that the contrast agent stays within the observation field of view during the period of acquiring the ultrasonic images of frame numbers 0 to n. Therefore, the line L3 having a high sound pressure of the ultrasonic wave is a curve in which the microbubbles of the contrast agent in the observation visual field are destroyed and the luminance decreases each time an ultrasonic image is acquired.

  Returning to FIG. 2, the control unit 38 controls the ultrasonic probe 2 so that the sound pressure of the ultrasonic wave becomes equal to or lower than the limit value (Step S5). Then, the ultrasound probe 2 transmits and receives ultrasound to and from the subject under the control of the ultrasound observation device 3 in a state where the sound pressure of the ultrasound is limited to the limit value or less. Under the control of the control unit 38, the ultrasonic image 5 is generated (Step S2). More specifically, the ultrasonic probe 2 transmits and receives the sound pressure of the ultrasonic wave at a limit value. As a result, the user can observe the subject with high luminance without destroying the contrast agent.

  As described above, according to the embodiment, since the ultrasonic waves are actually transmitted and received, the destructive sound pressure is determined, and the limit value is calculated, the characteristics of the subject and the characteristics of the organ to be observed and the like are obtained. Regardless of the position of the contrast agent in the subject, the contrast agent is not destroyed, and the subject can be observed with high luminance. Further, according to the embodiment, the sound pressure of the ultrasonic wave to be transmitted is gradually changed from the low sound pressure to the high sound pressure, and it is determined whether each sound pressure exceeds the destructive sound pressure. The contrast agent is prevented from being destroyed during the detection process. Further, according to the embodiment, since it is determined whether the sound pressure exceeds the destructive sound pressure in a state where the sound pressure and the frame rate are constant, the luminance caused by the inflow or outflow of the contrast agent or the like is determined. It is hard to be affected by the change of time.

  If the user changes the frame rate while the sound pressure restriction button is pressed and the control unit 38 controls the ultrasonic probe 2 so that the sound pressure of the ultrasonic wave becomes equal to or less than the limit value, It is preferable that the value calculation unit 36 calculates the limit value according to the frame rate again.

  Further, in the above-described embodiment, the limit value calculating unit 36 determines the destructive sound pressure using the slope of the approximate curve, but instead of the slope of the approximate curve, based on the amount of change in the average luminance value. Other calculated feature amounts may be used. For example, the limit value calculator 36 subtracts a value obtained by subtracting a value obtained by averaging the average luminance values of the frames F (N−5) to FN from a value obtained by averaging the average luminance values of the frames F1 to F5, and a threshold value. May be compared to determine the destructive sound pressure.

  Further, the ultrasonic probe 2 is not limited to an endoscope that inserts the ultrasonic transducer 21 into the body of the subject. For example, the above-described configuration is an extracorporeal type having a function of transmitting an ultrasonic pulse from a body surface in a subject toward the body and receiving an ultrasonic echo reflected in the subject and outputting an echo signal. May be applied to the ultrasonic probe.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

REFERENCE SIGNS LIST 1 ultrasonic observation system 2 ultrasonic probe 3 ultrasonic observation device 4 display device 5 ultrasonic image 21 ultrasonic transducer 31 transmission unit 32 reception unit 33 signal processing unit 34 image generation unit 35 average luminance value calculation unit 36 limit value calculation Unit 37 input unit 38 control unit 39 storage unit A area C center

Claims (8)

An ultrasonic observation apparatus that transmits an ultrasonic wave to a subject to which a contrast agent has been administered and generates an ultrasonic image based on an ultrasonic signal reflected by the contrast agent,
For each of the plurality of ultrasonic images generated by transmitting ultrasonic waves at a constant sound pressure, an average luminance value calculation unit that calculates an average luminance value in a predetermined region,
Based on the amount of change in the average luminance value, a limit value calculation unit that calculates a limit value of the sound pressure of the ultrasonic wave in which the contrast agent is not destroyed,
A control unit that controls the sound pressure of the ultrasonic wave to be transmitted to be limited to the limit value or less,
An ultrasonic observation apparatus comprising:   The ultrasonic observation apparatus according to claim 1, wherein the limit value calculation unit calculates the limit value based on an approximate curve calculated from a time change of the average luminance value.   The ultrasonic observation apparatus according to claim 1, wherein the predetermined area includes a center of the ultrasonic image.   The limit value calculation unit changes the sound pressure of the transmitted ultrasonic wave from a low sound pressure to a high sound pressure, and calculates the limit value based on the amount of change in the average luminance value calculated at each sound pressure. The ultrasonic observation apparatus according to claim 1, wherein:   The limit value calculation unit, when the relationship between the feature amount calculated based on the change amount of the average luminance value and the threshold value satisfies a predetermined condition, the threshold value transmitted when the condition is satisfied The ultrasonic observation apparatus according to claim 4, wherein the sound pressure of the ultrasonic wave transmitted immediately before the sound pressure of the sound wave is calculated as the limit value. The plurality of ultrasonic images are captured with a constant frame rate,
The ultrasonic observation apparatus according to claim 1, wherein the limit value calculation unit calculates the limit value according to the frame rate. A method for operating an ultrasonic observation apparatus that transmits an ultrasonic wave to a subject to which a contrast agent has been administered and generates an ultrasonic image based on an ultrasonic signal reflected by the contrast agent,
An average luminance value calculating unit calculates an average luminance value in a predetermined area for each of the plurality of ultrasonic images generated by transmitting ultrasonic waves at a constant sound pressure, and ,
A limit value calculation unit, based on the amount of change in the average luminance value, a limit value calculation step of calculating a limit value of the sound pressure of the ultrasonic wave in which the contrast agent is not destroyed,
The control unit, a control step of controlling the sound pressure of the ultrasonic wave to be transmitted to be limited to the limit value or less,
A method for operating an ultrasonic observation apparatus, comprising: An operating program of an ultrasonic observation apparatus that transmits an ultrasonic wave to a subject to which a contrast agent has been administered and generates an ultrasonic image based on an ultrasonic signal reflected by the contrast agent,
An average luminance value calculating unit calculates an average luminance value in a predetermined area for each of the plurality of ultrasonic images generated by transmitting ultrasonic waves at a constant sound pressure, and ,
A limit value calculation unit, based on the amount of change in the average luminance value, a limit value calculation step of calculating a limit value of the sound pressure of the ultrasonic wave in which the contrast agent is not destroyed,
The control unit, a control step of controlling the sound pressure of the ultrasonic wave to be transmitted to be limited to the limit value or less,
An operation program for an ultrasonic observation apparatus, wherein the operation program is executed by an ultrasonic observation apparatus.

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