Image processing device and method for controlling the image processing device

Abstract

This image processing device (1) comprises: an accuracy calculation unit (13) that analyzes an ultrasonic image of a subject for each frame and calculates the accuracy of a blood vessel in the ultrasonic image; a blood vessel detection unit (16) that detects a blood vessel of which the accuracy calculated by the accuracy calculation unit (13) is higher than an accuracy threshold; and an accuracy threshold change unit (15) that changes the accuracy threshold on the basis of a plurality of pieces of accuracy calculated by the accuracy calculation unit (13) for ultrasonic images of a plurality of frames.

Description

[Technical field]

[0001] The present invention relates to an image processing device for detecting blood vessels in an ultrasound image and a method for controlling the image processing device. [Background technology]

[0002] Conventionally, in preparation for inserting a puncture needle into a blood vessel of a subject, an ultrasound image of the subject is observed to confirm the blood vessel in the ultrasound image. It is generally known that a certain level of skill is required for an examiner such as a doctor to observe an ultrasound image and accurately recognize the position of the blood vessel. Therefore, in order for an examiner to easily confirm the blood vessel in the ultrasound image, a device for detecting blood vessels in the ultrasound image by analyzing the ultrasound image, such as that disclosed in Patent Document 1, has been developed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2012 / 147505 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, for example, in the case of a subject with a high body fat, the ultrasound image may be bright overall, and artifacts may appear in the blood vessels. In addition, for example, in the case of gas accumulation in the subject, the boundary between the blood vessels and the surrounding tissues in the ultrasound image may be blurred. As such, it is known that the appearance of blood vessels in an ultrasound image varies depending on the subject. Therefore, even if the technology disclosed in Patent Document 1 is used, depending on the subject, blood vessels in the ultrasound image may not be accurately detected.

[0005] An object of the present invention is to provide an image processing device and a control method for an image processing device that are capable of detecting blood vessels in an ultrasound image with high accuracy. [Means for solving the problem]

[0006] The image processing device of the present invention is characterized in that it comprises an accuracy calculation unit that analyzes ultrasound images of a subject for each frame and calculates the accuracy of blood vessels in the ultrasound image, a blood vessel detection unit that detects blood vessels whose accuracy calculated by the accuracy calculation unit is higher than an accuracy threshold, and a accuracy threshold change unit that changes the accuracy threshold based on multiple accuracy values ​​calculated by the accuracy calculation unit for multiple frames of ultrasound images.

[0007] The image processing device can include an ultrasonic probe, and an image generating unit that generates an ultrasonic image to be analyzed by the accuracy calculating unit based on transmission and reception of an ultrasonic beam using the ultrasonic probe. The image processing device can also include a probability memory for storing the probability calculated by the probability calculation section. Furthermore, the image processing device may include a device control unit that controls the storage of the probability in the probability memory.

[0008] The device control unit can determine that the ultrasonic probe is stationary, and when it is determined that the ultrasonic probe is stationary for a predetermined period of time or more, store the accuracy in an accuracy memory. The device control unit can also determine whether the ultrasound probe is in contact with the subject's body surface, and when it is determined that the ultrasound probe is in contact with the subject's body surface, store the accuracy in an accuracy memory.

[0009] Furthermore, when it is determined that the moving speed of the ultrasonic probe is lower than a predetermined moving speed, the device control section can store the accuracy in an accuracy memory. In addition, the device control unit can also store in an accuracy memory the accuracy calculated based on an ultrasound image of a frame selected from the multiple frames of ultrasound images generated by the image generation unit at a frame interval corresponding to the moving speed of the ultrasound probe.

[0010] The certainty threshold change unit can calculate a change value by multiplying the maximum value of multiple certainties calculated for multiple frames of ultrasound images by a determined rate, and change the certainty threshold to the change value. The certainty threshold change unit can also calculate a change value by statistically analyzing a plurality of certainties calculated for a plurality of frames of ultrasound images, and change the certainty threshold to the change value. It is preferable that the certainty threshold changing unit changes the certainty threshold to the changed value when the changed value is lower than the certainty threshold of the blood vessel detection unit.

[0011] The image processing device may include a change notification unit that notifies a user of a change in the certainty threshold. The image processing device may further include an accuracy threshold memory that stores, for each subject, the accuracy threshold changed by the accuracy threshold change unit. The image processing device may also have an input device for a user to perform an input operation, and a manual change section that changes the certainty threshold value based on the input operation via the input device.

[0012] The control method of an image processing device according to the present invention is characterized in that it analyzes ultrasound images of a subject for each frame to calculate the accuracy of blood vessels in the ultrasound image, detects blood vessels whose accuracy is higher than an accuracy threshold, and changes the accuracy threshold based on multiple accuracy values ​​calculated for multiple frames of ultrasound images. Effect of the Invention

[0013] According to the present invention, the image processing device is equipped with an accuracy calculation unit that analyzes multiple frames of ultrasound images of a subject for each frame and calculates the accuracy of blood vessels in the ultrasound images, a blood vessel detection unit that detects blood vessels whose accuracy calculated by the accuracy calculation unit is higher than an accuracy threshold, and an accuracy threshold changing unit that changes the accuracy threshold based on the multiple accuracy values ​​calculated by the accuracy calculation unit, thereby making it possible to detect blood vessels in ultrasound images with high accuracy. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram showing a configuration of an image processing device according to a first embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing an example of an ultrasound image including blood vessels. [Diagram 3] FIG. 4 is a diagram showing an example of a seek bar displayed on a monitor in the first embodiment of the present invention. [Figure 4] FIG. 3 is a diagram showing an example of a dialog panel according to the first embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram showing another example of the dialog panel in the first embodiment of the present invention. [Figure 6] 4 is a flowchart showing the operation of the image processing device according to the first embodiment of the present invention. [Figure 7] FIG. 11 is a block diagram showing the configuration of an ultrasound diagnostic apparatus according to a second embodiment of the present invention. [Figure 8] FIG. 11 is a block diagram showing a configuration of a transmission / reception circuit according to a second embodiment of the present invention. [Figure 9] FIG. 11 is a block diagram showing a configuration of an image generating unit according to a second embodiment of the present invention. [Figure 10] 6 is a flowchart showing the operation of the ultrasound diagnostic apparatus according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following description of the components will be given based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, the terms "same" and "identical" include a generally acceptable margin of error in the technical field.

[0016] First embodiment 1 shows the configuration of an image processing device 1 according to a first embodiment of the present invention. The image processing device 1 receives ultrasound images from an external device (not shown) such as an ultrasound diagnostic device, and displays and analyzes the ultrasound images.

[0017] The image processing device 1 includes a display control unit 11, to which a monitor 12 is connected. The image processing device 1 also includes an accuracy calculation unit 13, to which an accuracy memory 14 is connected, and to which an accuracy threshold value change unit 15 is connected. The accuracy threshold value change unit 15 also includes a blood vessel detection unit 16, an accuracy threshold value memory 17, and a change notification unit 19. The accuracy threshold value memory 17 is connected to the blood vessel detection unit 16. The image processing device 1 also includes a manual change unit 18, which is connected to the blood vessel detection unit 16 and the change notification unit 19. The blood vessel detection unit 16 and the change notification unit 19 are also connected to the display control unit 11.

[0018] In addition, a device control unit 20 is connected to the display control unit 11, the accuracy calculation unit 13, the accuracy memory 14, the accuracy threshold value change unit 15, the blood vessel detection unit 16, the accuracy threshold value memory 17, the manual change unit 18, and the change notification unit 19. In addition, an input device 21 is connected to the device control unit 20.

[0019] The display control unit 11, the accuracy calculation unit 13, the accuracy threshold change unit 15, the blood vessel detection unit 16, the manual change unit 18, the change notification unit 19 and the device control unit 20 form a processor 22. Moreover, the display control unit 11 and the accuracy calculation unit 13 receive ultrasonic images from an external device (not shown) such as a so-called ultrasonic diagnostic device.

[0020] The accuracy calculation unit 13 analyzes the ultrasound image of the subject for each frame and calculates the accuracy of blood vessels in the ultrasound image. Here, the accuracy of blood vessels in the ultrasound image is an index indicating the likelihood of a blood vessel-like structure included in the ultrasound image, and is expressed, for example, by the probability that the structure is a blood vessel. The accuracy calculation unit 13 calculates the accuracy of each blood vessel-like structure in the ultrasound image for each ultrasound image. Here, the blood vessels for which accuracy is calculated include veins and arteries.

[0021] The accuracy calculation unit 13 can calculate the accuracy of blood vessels by applying, for example, a method using simple template matching, a machine learning method described in Csurka et al.: Visual Categorization with Bags of Keypoints, Proc. of ECCV Workshop on Statistical Learning in Computer Vision, pp.59-74 (2004), or a general image recognition method using deep learning described in Krizhevsk et al.: ImageNet Classification with Deep Convolutional Neural Networks, Advances in Neural Information Processing Systems 25, pp.1106-1114 (2012), to the ultrasound image.

[0022] 2 shows an example of an ultrasound image U including blood vessel-like structures A1, A2, and A3. When calculating the accuracy for this ultrasound image U, the accuracy calculation unit 13 calculates the accuracy for each of the structures A1, A2, and A3.

[0023] The accuracy memory 14 is a memory for storing the accuracy calculated by the accuracy calculation unit 13. The accuracy stored in the accuracy memory 14 is sent to the accuracy threshold change unit 15 under the control of the device control unit 20.

[0024] In addition, the accuracy memory 14 may be, for example, a flash memory, a HDD (Hard Disc Drive), an SSD (Solid State Drive), an FD (Flexible Disc), an MO disk (Magneto-Optical disc), an MT (Magnetic Tape), a RAM (Random Access Memory), a CD (Compact Disc), a DVD (Digital Versatile Disc), an SD card (Secure Digital card), a USB memory (Universal Serial Bus memory), or other recording media.

[0025] The blood vessel detection unit 16 has an accuracy threshold for the accuracy of blood vessels, and detects blood vessels whose accuracy calculated by the accuracy calculation unit 13 is higher than the accuracy threshold. When the accuracy calculated by the accuracy calculation unit 13 is equal to or lower than the accuracy threshold, the blood vessel detection unit 16 does not detect blood vessels having that accuracy. For example, among the three structures A1, A2, and A3 shown in FIG. 2, when the accuracy for structures A1 and A2 is higher than the accuracy threshold and the accuracy for structure A3 is equal to or lower than the accuracy threshold, the blood vessel detection unit 16 detects structures A1 and A2 as blood vessels, and does not detect structure A3 as a blood vessel.

[0026] In this way, the ease of detecting blood vessels is determined by the certainty threshold value. That is, the higher the certainty threshold value is set, the more difficult it is to detect structures A1, A2, and A3 as blood vessels, and the lower the certainty threshold value is set, the more easily structures A1, A2, and A3 are detected as blood vessels.

[0027] The accuracy threshold change unit 15 calculates an accuracy change value for each of the structures A1, A2, and A3 based on multiple accuracy values ​​calculated by the accuracy calculation unit 13 for multiple frames of ultrasound image U, and changes the accuracy threshold of the blood vessel detection unit 16 to the change value.

[0028] The accuracy threshold modification unit 15 can calculate the modification value, for example, by multiplying the highest accuracy value calculated for multiple frames of ultrasound image U by a specified ratio smaller than 1.0, such as 0.8. At this time, it is desirable for the certainty threshold value changing unit 15 to exclude certainty having a value equivalent to a so-called outlier. For example, the certainty threshold value changing unit 15 calculates the average value and standard deviation of a plurality of certainties, and further excludes certainty having a value equal to or greater than the sum of three times the calculated standard deviation and the average value from the plurality of certainties, thereby being able to exclude certainty equivalent to an outlier.

[0029] The certainty threshold change unit 15 can also calculate the change value by statistically analyzing the multiple certainties calculated for the multiple frames of ultrasound images U. Statistically analyzing the multiple certainties refers to analyzing the distribution of the multiple certainty values. The certainty threshold change unit 15 can, for example, sort the multiple certainties in ascending or descending order, and calculate the value of the certainty located in a rank corresponding to a predetermined ratio, such as the top 20%, of the total number of the multiple certainties, with the highest certainty being ranked first, as the change value. The certainty threshold change unit 15 can also, for example, sort the multiple certainties in ascending or descending order, and calculate the value of the certainty located in a rank corresponding to a predetermined ratio, such as the top 20%, of the total number of the multiple certainties, with the highest certainty being ranked first, as the change value.

[0030] As an example of statistically analyzing multiple probabilities, the probability threshold change unit 15 can also calculate, for example, the sum of a constant multiple of the standard deviation of the multiple probabilities and the average value of the multiple probabilities as a change value.

[0031] The accuracy threshold memory 17 is a memory that stores the accuracy threshold changed by the accuracy threshold changing unit 15 for each subject. The accuracy threshold stored in the accuracy threshold memory 17 is sent to the blood vessel detection unit 16 under the control of the device control unit 20, for example, at the start of an examination of the subject corresponding to that accuracy threshold, and is used as the initial value of the accuracy threshold of the blood vessel detection unit 16.

[0032] As the accuracy threshold memory 17, for example, a recording medium such as a flash memory, HDD, SSD, FD, MO disk, MT, RAM, CD, DVD, SD card, or USB memory can be used.

[0033] The input device 21 is used by the user to perform input operations and is configured by devices such as a keyboard, a mouse, a trackball, a touch pad, and a touch panel that allow the user to perform input operations.

[0034] The manual change unit 18 changes the certainty threshold to a value designated based on the user's input operation via the input device 21. An example of the user's input operation via the input device 21 is, for example, an input operation using the seek bar B shown in FIG. 3. The seek bar B has a slide button B1 that slides between both ends, and the certainty threshold corresponding to the position of the slide button B1 can be designated. For example, in order to make it easy for the user to intuitively grasp the meaning of the certainty threshold, the left end of the seek bar B can be displayed as "detectability 0" and the right end as "detectability 100" on the monitor 12 by making the range determined for the certainty correspond to the range of detectability from 0 to 100. In this case, the user can designate a lower certainty threshold by moving the slide button B1 closer to the left end of the seek bar B, "detectability 0", and can designate a higher certainty threshold by moving the slide button B1 closer to the right end of the seek bar B, "detectability 100".

[0035] The change notification unit 19 notifies the user of the change in the certainty threshold value. 4, for example, when the certainty threshold is about to be changed, the change notification unit 19 can display a dialogue panel P1 on the monitor 12 for selecting whether to execute or cancel the change of the certainty threshold. This dialogue panel P1 includes a message "Do you want to change the detectability of blood vessels?", the detectability values ​​before and after the change, an execute button C1 for executing the change of the certainty threshold, and a cancel button C2 for canceling the change of the certainty threshold.

[0036] Furthermore, when the certainty threshold is about to be changed, the change notification unit 19 can classify the detectability of blood vessels into a number of stages, such as "very difficult to detect," "difficult to detect," "normal," "easy to detect," and "very easy to detect," and display the classified stages instead of the values ​​of the detectability before and after the change in the dialogue panel P1. For example, in the dialogue panel P2 shown in Fig. 5, "easy to detect" is displayed as the detectability before the change, and "normal" is displayed as the detectability after the change.

[0037] The device control section 20 controls each section of the image processing device 1 according to a prerecorded program or the like. Under the control of the device control unit 20, the display control unit 11 performs predetermined processing on the ultrasound image U and the structures A1, A2, etc. detected as blood vessels by the blood vessel detection unit 16, and displays the results on the monitor 12.

[0038] The monitor 12 performs various displays under the control of the display control unit 11. The monitor 12 includes a display device such as an LCD (Liquid Crystal Display) or an organic EL display (Organic Electroluminescence Display).

[0039] The processor 22 having the display control unit 11, accuracy calculation unit 13, accuracy threshold change unit 15, blood vessel detection unit 16, manual change unit 18, change notification unit 19 and device control unit 20 is composed of a CPU (Central Processing Unit) and a control program for causing the CPU to perform various processes, but may also be composed of an FPGA (Field Programmable Gate Array), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit) or other ICs (Integrated Circuits), or may be composed of a combination of these.

[0040] In addition, the display control unit 11, the accuracy calculation unit 13, the accuracy threshold change unit 15, the vascular detection unit 16, the manual change unit 18, the change notification unit 19 and the device control unit 20 of the processor 22 can also be configured as being partially or wholly integrated into a single CPU or the like.

[0041] Next, the operation of the image processing device 1 according to the first embodiment of the present invention will be described with reference to the flowchart shown in Fig. 6. It is assumed that a plurality of frames of ultrasound images U capturing the same part of the same subject are input in advance to the image processing device 1 from an external device such as an ultrasound diagnostic device (not shown).

[0042] First, in step S1, the device control unit 20 receives an instruction to start a series of processes for detecting blood vessels (the processes of steps S2 to S6). For example, when an instruction to start a series of processes for detecting blood vessels is given by a user's input operation via the input device 21, the instruction is received by the device control unit 20.

[0043] Next, in step S2, the accuracy calculation unit 13 calculates the accuracy of blood vessels for each ultrasound image U input from an external device such as an ultrasound diagnostic device. For example, as shown in Fig. 2, when three blood vessel-like structures A1, A2, and A3 are included in the ultrasound image U, the accuracy is calculated for each of the three structures A1, A2, and A3 for each ultrasound image U. The multiple probabilities calculated in this manner are stored in the probability memory 14.

[0044] In the following step S3, the accuracy threshold modification unit 15 calculates a modification value for the accuracy threshold of the blood vessel detection unit 16 for each of the structures A1 to A3 in the ultrasound image U, based on the multiple accuracy values ​​calculated in step S2 and stored in the accuracy memory 14. The accuracy threshold modification unit 15 calculates the modification value by multiplying the maximum value of the multiple accuracy values ​​calculated for the multiple frames of the ultrasound image U by a predetermined ratio, such as 0.8.

[0045] Here, it is known that, for example, an ultrasound image of a subject with a high body fat has high brightness overall, and blood vessels in the ultrasound image may contain artifacts, and when gas is accumulated in the subject, the boundary between the blood vessels and the surrounding tissue in the ultrasound image may become blurred, making it difficult to see blood vessels in the ultrasound image depending on the subject. Thus, when the accuracy of blood vessels is calculated for an ultrasound image in which blood vessels are difficult to see, the accuracy calculated has a lower value than the accuracy calculated for an ultrasound image in which blood vessels appear normal.

[0046] Since the modified value calculated by the accuracy threshold modification unit 15 is lower than the maximum accuracy value calculated for multiple frames of ultrasound images U of the same subject, even if structures A1 to A3 in the ultrasound image U become difficult to see due to the condition of the subject, structures A1 to A3 can be easily detected as blood vessels.

[0047] In step S4, the accuracy threshold change unit 15 changes the accuracy threshold of the blood vessel detection unit 16 to the change value calculated in step S3.

[0048] Here, when the accuracy threshold change unit 15 attempts to change the accuracy threshold of the blood vessel detection unit 16, the change notification unit 19 can change the change of the accuracy threshold to the user. For example, as shown in FIG. 4, the change notification unit 19 can display a dialogue panel P1 on the monitor 12 to allow the user to select whether to execute or cancel the change of the accuracy threshold. At this time, when the user selects the execute button C1 via the input device 21, the accuracy threshold change unit 15 changes the accuracy threshold of the blood vessel detection unit 16 to the change value calculated in step S3. Also, when the user selects the cancel button C2, the change of the accuracy threshold by the accuracy threshold change unit 15 is canceled. In this way, by notifying the user of the change in the accuracy threshold, the user can clearly understand that the ease of detecting blood vessels has changed.

[0049] In step S4, in addition to the change of the certainty threshold by the certainty threshold change unit 15, the certainty threshold can also be changed by the manual change unit 18. In this case, for example, as shown in Fig. 3, the user specifies the certainty threshold by sliding the slide button B1 of the seek bar B via the input device 21, and the manual change unit 18 changes the certainty threshold to the value specified by the user. In this way, by changing the accuracy threshold based on an input operation via the input device 21, the ease of blood vessel detection can be adjusted in more detail.

[0050] The accuracy threshold changed in step S4 is stored for each subject in the accuracy threshold memory 17. The accuracy threshold stored here can be read out under the control of the device control unit 20 at the start of the next examination on the same subject, for example, and used as the initial value of the accuracy threshold of the blood vessel detection unit 16.

[0051] In step S5, the blood vessel detection unit 16 detects blood vessels with a higher probability than the probability threshold changed in step S4. For example, when the probability calculated for the structures A1 and A2 shown in Fig. 2 is higher than the probability threshold and the probability calculated for the structure A3 is equal to or lower than the probability threshold, the blood vessel detection unit 16 detects the structures A1 and A2 as blood vessels among the structures A1 to A3 and does not detect the structure A3 as a blood vessel.

[0052] Finally, in step S6, the blood vessel detection unit 16 highlights the structures A1 and A2 detected as blood vessels in step S5 and displays them on the monitor 12. Although not shown, the blood vessel detection unit 16 can, for example, superimpose the contours of the structures A1 and A2 detected as blood vessels on the ultrasound image U and display them on the monitor 12. In addition, for example, the structures A1 and A2 can be highlighted by being given a color different from the surroundings. This allows the user to easily recognize the structures A1 and A2 as blood vessels.

[0053] As described above, according to the image processing device 1 of embodiment 1 of the present invention, the accuracy threshold is changed based on multiple accuracy calculated by the accuracy calculation unit 13 for multiple frames of ultrasound image U, so that blood vessels can be detected with high accuracy even if they are difficult to see in the ultrasound image U due to the condition of the subject.

[0054] In addition, in step S4, if the changed value calculated in step S3 is equal to or greater than the initial value of the accuracy threshold of the blood vessel detection unit 16, it is desirable for the accuracy threshold change unit 15 not to change the accuracy threshold in order to prevent blood vessels from becoming difficult to detect.

[0055] In addition, if the accuracy threshold is very low compared to a general value, there is a high possibility that blood vessels will be erroneously detected, and conversely, if the accuracy threshold is very high compared to a general value, there is a possibility that blood vessels will not be detected. Therefore, it is desirable to set an upper limit and a lower limit for the accuracy threshold. For example, the lower limit can be set to 0.8 times the initial value of the accuracy threshold, and the upper limit can be set to 1.2 times. As a more specific example, if the initial value of the accuracy threshold is 0.75, the lower limit can be set to 0.60 and the upper limit can be set to 0.90.

[0056] Also, while it has been explained that the change notification unit 19 notifies the user of the change in the accuracy threshold when the accuracy threshold change unit 15 attempts to change the accuracy threshold, it can also notify the user that the accuracy threshold has already been changed. This allows the user to smoothly check blood vessels while clearly understanding that the accuracy threshold has been changed.

[0057] Embodiment 2 The image processing device 1 of the first embodiment receives an ultrasound image U from an external device (not shown), but is not particularly limited to this aspect. For example, the image processing device 1 may be an ultrasound diagnostic device equipped with an ultrasound probe, and can analyze an ultrasound image U captured using this ultrasound probe.

[0058] FIG. 7 shows the configuration of an ultrasound diagnostic apparatus 1A according to the second embodiment. The ultrasonic diagnostic apparatus 1A includes an ultrasonic probe 2 and a diagnostic apparatus main body 3, and the ultrasonic probe 2 and the diagnostic apparatus main body 3 are connected to each other. The ultrasonic probe 2 includes a transducer array 31 to which a transmission / reception circuit 32 is connected.

[0059] The diagnostic device main body 3 is the image processing device 1 of the first embodiment to which an image generating unit 33 has been added, a device control unit 20A has been provided instead of the device control unit 20, and a processor 22A including the image generating unit 33 has been configured instead of the processor 22. The image generating unit 33 is connected to a transmission / reception circuit 32. In addition, a display control unit 11 and an accuracy calculation unit 13 are connected to the image generating unit 33. Compared to the device control unit 20 in the first embodiment, the device control unit 20A is further connected to the transmission / reception circuit 32 and the image generating unit 33.

[0060] The transducer array 31 of the ultrasonic probe 2 has a plurality of transducers arranged one-dimensionally or two-dimensionally. Each of these transducers transmits ultrasonic waves in accordance with a drive signal supplied from the transmission / reception circuit 32, receives ultrasonic echoes from the subject, and outputs a signal based on the ultrasonic echoes. Each transducer is configured by forming electrodes on both ends of a piezoelectric body made of, for example, a piezoelectric ceramic represented by PZT (Lead Zirconate Titanate), a polymeric piezoelectric element represented by PVDF (Poly Vinylidene Di Fluoride), or a piezoelectric single crystal represented by PMN-PT (Lead Magnesium Niobate-Lead Titanate).

[0061] The transmission / reception circuit 32, under the control of the device control unit 20A, transmits ultrasonic waves from the transducer array 31 and generates sound ray signals based on reception signals acquired by the transducer array 31. As shown in Fig. 8, the transmission / reception circuit 32 has a pulser 41 connected to the transducer array 31, and an amplifier 42, an AD (Analog-to-Digital) converter 43, and a beamformer 44, which are connected in series from the transducer array 31 in this order.

[0062] The pulser 41 includes, for example, a plurality of pulse generators, and adjusts the delay amount of each drive signal and supplies it to the plurality of transducers based on a transmission delay pattern selected in response to a control signal from the device control unit 20A so that ultrasonic waves transmitted from the plurality of transducers of the transducer array 31 form an ultrasonic beam. In this way, when a pulsed or continuous wave voltage is applied to the electrodes of the transducers of the transducer array 31, the piezoelectric body expands and contracts, and each transducer generates a pulsed or continuous wave ultrasonic wave, and an ultrasonic beam is formed from the composite wave of those ultrasonic waves.

[0063] The transmitted ultrasonic beam is reflected by an object such as a part of the subject, and propagates toward the transducer array 31 of the ultrasonic probe 2. The ultrasonic echo propagating toward the transducer array 31 in this manner is received by each transducer constituting the transducer array 31. At this time, each transducer constituting the transducer array 31 expands and contracts upon receiving the propagating ultrasonic echo, generating received signals which are electrical signals, and outputs these received signals to the amplifier 42.

[0064] The amplifier 42 amplifies the signal input from each transducer constituting the transducer array 31 and transmits the amplified signal to the AD converter 43. The AD converter 43 converts the signal transmitted from the amplifier 42 into digital reception data and transmits the reception data to the beamformer 44. The beamformer 44 performs so-called reception focusing processing by adding each reception data converted by the AD converter 43 with a delay according to the sound speed or sound speed distribution set based on the reception delay pattern selected in response to a control signal from the device control unit 20A. By this reception focusing processing, each reception data converted by the AD converter 43 is phased and added, and a sound ray signal with a narrowed focus of the ultrasonic echo is obtained. This sound ray signal is sent to the image generator 33.

[0065] As shown in FIG. 9, the image generating unit 33 has a configuration in which a signal processing unit 45, a DSC (Digital Scan Converter) 46, and an image processing unit 47 are connected in series. The signal processing unit 45 performs correction for attenuation due to distance on the sound ray signals sent from the transmission / reception circuit 32 in accordance with the depth of the ultrasonic reflection position, and then performs envelope detection processing to generate a B-mode image signal, which is tomographic image information regarding the tissue in the subject.

[0066] The DSC 46 converts (raster converts) the B-mode image signal generated by the signal processor 45 into an image signal conforming to a normal television signal scanning method. The image processing unit 47 performs various necessary image processing such as gradation processing on the B-mode image signal input from the DSC 46, and then sends the B-mode image signal to the display control unit 11 and the accuracy calculation unit 13 in response to a command from the device control unit 20. The B-mode image signal that has been subjected to image processing by the image processing unit 47 is simply referred to as an ultrasound image U.

[0067] Next, the operation of the ultrasound diagnostic apparatus 1A according to the second embodiment will be described with reference to the flowchart shown in Fig. 10. Steps S14 and S16 to S19 in this flowchart are the same as steps S2 and S3 to S6, respectively, in the flowchart according to the first embodiment shown in Fig. 6.

[0068] First, in step S11, an ultrasound image U is captured while the ultrasound probe 2 is brought into contact with the body surface of the subject to be examined by a user so that the blood vessels of the subject are imaged. At this time, the transmission / reception circuit 32 performs reception focusing processing using a preset sound velocity value under the control of the device control unit 20A to generate a sound ray signal. The sound ray signal generated by the transmission / reception circuit 32 in this manner is sent to the image generation unit 33. The image generation unit 33 generates an ultrasound image U using the sound ray signal sent from the transmission / reception circuit 32. The ultrasound image U generated in this manner is sent to the display control unit 11 and displayed on the monitor 12.

[0069] In step S12, the device control unit 20A determines whether or not an instruction to start a series of processes for detecting blood vessels (the processes of steps S13 to S19) has been accepted. For example, if an instruction to start a series of processes for detecting blood vessels is not input by a user's input operation via the input device 21, the device control unit 20A determines that this instruction has not been accepted and returns to step S11. When a new ultrasound image U is generated in step S11, the process proceeds to step S12. In this way, steps S11 and S12 are repeated while it is determined that an instruction to start a series of processes for detecting blood vessels has not been accepted.

[0070] The user checks the ultrasound images U sequentially generated by repeating steps S11 and S12, and when the user recognizes that an ultrasound image U including structures A1 to A3 resembling blood vessels of the subject to be examined, for example as shown in Fig. 2, has been obtained, the user inputs an instruction to start a series of processes for detecting blood vessels via the input device 21. When an instruction to start a series of processes is thus input, in step S12, the device control unit 20A determines that the instruction to start a series of processes has been accepted, and proceeds to step S13.

[0071] In step S13, an ultrasound image U is generated in the same manner as in step S11. In step S14, the accuracy calculation unit 13 analyzes the ultrasound image U generated in step S13 and calculates the accuracy of the structures A1 to A3 in the ultrasound image U. The blood vessel accuracy thus calculated for the structures A1 to A3 is stored in the accuracy memory 14 under the control of the device control unit 20A.

[0072] In step S15, the device control unit 20A determines whether the number of frames of the ultrasound image U for which the blood vessel accuracy was calculated in step S14 is N. Here, N is an integer equal to or greater than 2, and is set to, for example, 20 to 100. At this point in time, the ultrasound image U for which the blood vessel accuracy was calculated in step S14 is only one frame, so it is determined that the number of frames of the ultrasound image U for which the blood vessel accuracy was calculated in step S14 is not N, and the process returns to step S13. In this manner, steps S13 to S15 are repeated until the number of frames of the ultrasound image U for which the blood vessel accuracy was calculated in step S14 becomes N, and the calculated accuracy is stored in the accuracy memory 14 in sequence.

[0073] If it is determined in step S15 that the number of frames of the ultrasound image U for which the blood vessel accuracy was calculated in step S14 is N, the process proceeds to step S16. In step S16, the accuracy threshold change unit 15 calculates a change value for the accuracy threshold of the blood vessel detection unit 16 based on the multiple accuracy calculated for the N frames of ultrasound image U by repeating steps S13 to S15.

[0074] In step S17, the accuracy threshold change unit 15 changes the initial value of the accuracy threshold of the blood vessel detection unit 16 to a changed value. In step S18, the blood vessel detection unit 16 detects blood vessels having a higher certainty than the certainty threshold changed in step S17 from the ultrasound image U generated last in the repetition of steps S13 to S15, i.e., the latest ultrasound image U. For example, among the blood vessel-like structures A1 to A3 shown in Fig. 2, when the certainty of structures A1 and A2 is higher than the certainty threshold and the certainty of structure A3 is lower than the certainty threshold, the blood vessel detection unit 16 detects structures A1 and A2 as blood vessels.

[0075] Finally, in step S19, the blood vessel detection unit 16 highlights the structures A1 and A2 detected as blood vessels in step S18 in the latest ultrasound image U and displays them on the monitor 12.

[0076] As described above, according to the ultrasound diagnostic device 1A of embodiment 2 of the present invention, the accuracy threshold is changed based on multiple accuracy calculated by the accuracy calculation unit 13 for N frames of ultrasound image U, so that even if blood vessels in the ultrasound image U are difficult to see due to the condition of the subject, the blood vessels can be detected with high accuracy, as with the image processing device 1 of embodiment 1.

[0077] As shown in FIG. 7, the transmission / reception circuit 32 is provided in the ultrasonic probe 2, but it may be provided in the diagnostic device main body 3 instead of in the ultrasonic probe 2. Further, the image generating unit 33 is provided in the diagnostic device main body 3, but it may be provided in the ultrasound probe 2 instead of in the diagnostic device main body 3. As shown in FIG. 9, the image generating unit 33 includes a signal processing unit 45, a DSC 46, and an image processing unit 47, and among these, the signal processing unit 45 can be included in the ultrasonic probe 2.

[0078] Furthermore, the method of connecting the ultrasonic probe 2 and the diagnostic apparatus main body 3 is not particularly limited, and may be a wired connection or a wireless connection. Moreover, the diagnostic device main body 3 may be a so-called handheld type that can be easily carried by the user, or may be a so-called stationary type.

[0079] Furthermore, in step S12, when an instruction to start a series of processes for detecting blood vessels is input by the user via the input device 21, the device control unit 20A determines that the instruction has been accepted. However, the trigger for determining that an instruction to start a series of processes for detecting blood vessels has been accepted is not particularly limited to an instruction being input via the input device 21.

[0080] For example, the device control unit 20A can determine whether or not the ultrasonic probe 2 is in contact with the subject's body surface, and if it is determined that the ultrasonic probe 2 is in contact with the subject's body surface, it can determine that an instruction to start a series of processes for detecting blood vessels has been accepted.

[0081] To determine whether the ultrasonic probe 2 is in contact with the subject's body surface, for example, a pressure sensor (not shown) for measuring the contact pressure of the ultrasonic probe 2 against the subject's body surface is attached to the ultrasonic probe 2, and the device control unit 20A can determine that the ultrasonic probe 2 is in contact with the subject's body surface if the pressure value measured by the pressure sensor exceeds a predetermined pressure threshold, and determine that the ultrasonic probe 2 is separated from the subject's body surface if the measured pressure value is equal to or less than the predetermined pressure threshold.

[0082] It is also known that when the ultrasonic probe 2 is in contact with the subject's body surface, an ultrasonic image U having a certain level of brightness or more corresponding to the tissue in the subject is captured, but when the ultrasonic probe 2 is away from the subject's body surface, that is, in a so-called air radiation state, an ultrasonic image U entirely filled in black is captured because the ultrasonic echo does not propagate to the transducer array 31. Therefore, the device control unit 20A can determine that the ultrasonic probe 2 is in contact with the subject's body surface when an ultrasonic image U having a certain level of brightness or more is captured, and can determine that the ultrasonic probe 2 is away from the subject's body surface when an ultrasonic image U entirely filled in black is captured.

[0083] Also, for example, when capturing an ultrasound image U is started, the device control section 20A can determine that an instruction to start a series of processes for detecting blood vessels has been accepted. These methods determine that an instruction to start a series of processes for detecting blood vessels has been accepted, thereby eliminating the need for the user to perform input operations via the input device 21, and allowing the series of processes for detecting blood vessels to be executed more smoothly.

[0084] Furthermore, the processes of steps S13 to S15 are repeated until the accuracy of blood vessels is calculated for the predetermined N frames of ultrasound images U, but the processes of steps S13 to S15 may be repeated until a predetermined time has elapsed since the start of the initial process of step S13. In this case, in step S15, the device control unit 20A determines whether or not a predetermined time has elapsed since the start of the initial process of step S13. This predetermined time can be set to, for example, 1 second to 5 seconds.

[0085] Furthermore, the user can set in advance via the input device 21 the determined number of frames of the ultrasound image U used for the determination in step S15 and the elapsed time from the start of the first step S13.

[0086] Furthermore, the number of frames and the elapsed time can be set for each user who uses the ultrasonic diagnostic device 1A and stored in the device control unit 20A. In this case, for example, when starting an examination of a subject, the user who uses the ultrasonic diagnostic device 1A is authenticated, and the number of frames or the elapsed time stored corresponding to the authenticated user is read out, and the read number of frames or the elapsed time can be used for the judgment in step S15.

[0087] Examples of methods for authenticating a user include a method of inputting an identifier corresponding to the user from input device 21, a method of providing a fingerprint sensor (not shown) in ultrasound diagnostic apparatus 1A and recognizing the user's fingerprint, a method of providing a camera (not shown) in ultrasound diagnostic apparatus 1A and recognizing the user's face photographed by the camera, a method of photographing the user's eyes with a camera and recognizing the user's iris, a method of providing a microphone (not shown) in ultrasound diagnostic apparatus 1A and recognizing a voiceprint from the user's voice recorded by the microphone, a method of reading a barcode (one-dimensional code) corresponding to the user, a method of reading a two-dimensional code such as a QR (Quick Response) code (registered trademark) corresponding to the user, and the like.

[0088] Furthermore, in step S14, the device control section 20A stores the accuracy in the accuracy memory 14 each time the accuracy is calculated by the accuracy calculation section 13, but the timing at which the accuracy is stored is not particularly limited to this.

[0089] Generally, when an ultrasound image U including blood vessels is captured, the ultrasound probe 2 is often stationary. Therefore, for example, it is possible to determine that the ultrasound probe 2 is stationary, and if it is determined that the ultrasound probe 2 has been stationary for a specified period of time or longer, the calculated accuracy can be stored in the accuracy memory 14.

[0090] For example, motion sensors such as acceleration sensors or gyro sensors and pressure sensors can be attached to detect the movement of the ultrasonic probe 2, and the device control unit 20A can determine that the ultrasonic probe 2 is stationary based on the values ​​measured by these sensors. Furthermore, since similar ultrasound images U are often captured successively when the ultrasound probe 2 is stationary, the device control unit 20A can, for example, calculate the overall image similarity between the ultrasound images U successively generated by the image generation unit 33, and determine that the ultrasound probe 2 is stationary when the calculated similarity is equal to or greater than a predetermined similarity threshold.

[0091] In addition, since the accuracy of blood vessels cannot be calculated when the ultrasonic probe 2 is separated from the subject's body surface, the device control unit 20A determines whether or not the ultrasonic probe 2 is in contact with the subject's body surface, for example, by analyzing the ultrasonic image U or by making a judgment using the measurement value of a pressure sensor attached to the ultrasonic probe 2, and can store the accuracy when it is determined that the ultrasonic probe 2 is in contact with the subject's body surface, and can stop storing the accuracy when it is determined that the ultrasonic probe 2 is separated from the subject's body surface.

[0092] Furthermore, when the user is unable to image the blood vessel of the inspection target, the moving speed of the ultrasonic probe 2 is often relatively high, and when the user is able to image the blood vessel of the inspection target, the moving speed of the ultrasonic probe 2 is often relatively low. Therefore, the device control unit 20A determines whether the moving speed of the ultrasonic probe 2 is lower than a determined moving speed, and when it is determined that the moving speed of the ultrasonic probe 2 is lower than the determined moving speed, it can store the accuracy.

[0093] The moving speed of the ultrasonic probe 2 can be measured, for example, by attaching an acceleration sensor (not shown) to the ultrasonic probe 2. In this case, the device control unit 20A can determine whether the moving speed measured by the sensor attached to the ultrasonic probe 2 is lower than a predetermined moving speed.

[0094] In addition, when the moving speed of the ultrasonic probe 2 is low, the similarity between the ultrasonic images U continuously generated by the image generating unit 33 is relatively large, and when the moving speed of the ultrasonic probe 2 is high, the similarity between the ultrasonic images U continuously generated is relatively small. Therefore, the device control unit 20A can calculate the similarity between the frames continuously generated by the image generating unit 33, for example, and determine that the larger the calculated similarity is, the higher the moving speed of the ultrasonic probe 2 is, and the lower the calculated similarity is, the lower the moving speed of the ultrasonic probe 2 is. Therefore, the device control unit 20A can estimate the moving speed of the ultrasonic probe 2 from the similarity between the ultrasonic images U continuously generated by the image generating unit 33, and determine whether the estimated moving speed is lower than a predetermined moving speed.

[0095] In addition, since the moving speed of the ultrasound probe 2 is often relatively high when the user is unable to photograph the blood vessels to be examined, and the moving speed of the ultrasound probe 2 is often relatively low when the user is able to photograph the blood vessels to be examined, in order to improve the accuracy of the changed value calculated by the accuracy threshold change unit 15, it is preferable to increase the number of accuracy levels to be saved as the moving speed of the ultrasound probe 2 is slower, and to decrease the number of accuracy levels to be saved as the moving speed of the ultrasound probe 2 is faster.

[0096] Therefore, for example, the device control unit 20A can store in the accuracy memory 14 the accuracy corresponding to the ultrasound image U selected at a longer frame interval as the moving speed of the ultrasound probe 2 is higher, and can store in the accuracy memory 14 the accuracy corresponding to the ultrasound image U selected at a shorter frame interval as the moving speed of the ultrasound probe 2 is lower. In this way, the device control unit 20A can store in the accuracy memory 14 the accuracy calculated based on the ultrasound image U of a frame selected at a frame interval according to the moving speed of the ultrasound probe 2 from among the multiple frames of ultrasound images U generated by the image generation unit 33.

[0097] 10 shows a mode in which the accuracy threshold is changed only once, but if ultrasound images U are continuously generated even after the accuracy threshold is changed, a change value can be calculated and the accuracy threshold of the blood vessel detection unit 16 can be changed to the change value every time the accuracy for N frames of ultrasound images U is calculated. In this case, the accuracy threshold can be changed sequentially to a change value with higher accuracy.

[0098] Furthermore, when ultrasound images U are continuously generated even after the accuracy threshold is changed, the accuracy threshold can be changed a set number of times, for example, 1 to 5 times, and the change in the accuracy threshold can be stopped thereafter. If blood vessels in the ultrasound image U cannot be detected for some reason, it is difficult to determine whether the cause is due to the ultrasound image U or the change in the accuracy threshold. Therefore, by determining the number of times the accuracy threshold can be changed, even if blood vessels in the ultrasound image U cannot be detected, the user can easily determine the cause and take appropriate measures.

[0099] The changed certainty threshold value can also be reset to the initial value of the certainty threshold value. For example, the certainty threshold value change unit 15 can reset the value of the certainty threshold value by inputting a reset instruction by the user's input operation via the input device 21. Furthermore, when the certainty threshold value has been changed multiple times, a reset process may be performed to change the certainty threshold value to the previous certainty threshold value a set number of times, such as resetting the certainty threshold value to the certainty threshold value immediately before being changed to the latest certainty threshold value, instead of the initial value of the certainty threshold value. In this way, by resetting the certainty threshold value, for example, even if the certainty threshold value deviates from the appropriate value for some reason, the certainty threshold value change unit 15 can change the certainty threshold value back to an appropriate value. [Explanation of symbols]

[0100] 1 image processing device, 1A ultrasound diagnostic device, 2 ultrasound probe, 3 diagnostic device main body, 11 display control unit, 12 monitor, 13 accuracy calculation unit, 14 accuracy memory, 15 accuracy threshold change unit, 16 blood vessel detection unit, 17 accuracy threshold memory, 18 manual change unit, 19 change notification unit, 20, 20A device control unit, 21 input device, 22, 22A processor, 31 transducer array, 32 transmission / reception circuit, 33 image generation unit, 41 pulser, 42 amplifier unit, 43 AD conversion unit, 44 beamformer, 45 signal processing unit, 46 DSC, 47 image processing unit, A1 to A3 structure, B seek bar, B1 slide button, C1 execute button, C2 cancel button, P1, P2 dialog panel, U ultrasound image.

Claims

1. an accuracy calculation unit that analyzes an ultrasound image of a subject for each frame and calculates an accuracy of blood vessels in the ultrasound image; a blood vessel detection unit that detects the blood vessels whose certainty calculated by the certainty calculation unit is higher than a certainty threshold; an accuracy threshold changing unit that changes the accuracy threshold based on a plurality of the accuracy values ​​calculated by the accuracy calculation unit for a plurality of frames of the ultrasound images; An image processing device comprising:

2. An ultrasonic probe; an image generating unit that generates the ultrasonic image analyzed by the accuracy calculating unit based on transmission and reception of an ultrasonic beam using the ultrasonic probe; The image processing device according to claim 1 .

3. The image processing device according to claim 2 , further comprising a probability memory for storing the probability calculated by the probability calculation unit.

4. The image processing device according to claim 3 , further comprising a device control unit that controls the saving of the probability in the probability memory.

5. The image processing device according to claim 4 , wherein the device control unit determines that the ultrasonic probe is stationary, and when it is determined that the ultrasonic probe is stationary for a predetermined time or more, stores the accuracy in the accuracy memory.

6. The image processing device according to claim 4, wherein the device control unit determines that the ultrasound probe is in contact with the body surface of the subject, and when it is determined that the ultrasound probe is in contact with the body surface of the subject, stores the accuracy in the accuracy memory.

7. The image processing apparatus according to claim 4 , wherein the device control unit stores the degree of certainty in the degree of certainty memory when it is determined that the moving speed of the ultrasonic probe is lower than a predetermined moving speed.

8. The image processing device according to claim 4, wherein the device control unit stores in the accuracy memory the accuracy calculated based on the ultrasound image of a frame selected from the multiple frames of ultrasound images generated by the image generation unit at a frame interval corresponding to the moving speed of the ultrasound probe.

9. An image processing device as described in any one of claims 1 to 8, wherein the certainty threshold change unit calculates a change value by multiplying the highest value of the multiple certainties calculated for the multiple frames of ultrasound images by a predetermined ratio, and changes the certainty threshold to the change value.

10. An image processing device as described in any one of claims 1 to 8, wherein the certainty threshold change unit calculates a change value by statistically analyzing the multiple certainties calculated for the multiple frames of ultrasound images, and changes the certainty threshold to the change value.

11. The image processing device according to claim 9 , wherein the certainty threshold changing unit changes the certainty threshold to the changed value when the changed value is lower than the certainty threshold of the blood vessel detection unit.

12. 12. The image processing device according to claim 1, further comprising a change notification unit that notifies a user of a change in the certainty threshold value.

13. 13. The image processing apparatus according to claim 1, further comprising an accuracy threshold memory that stores the accuracy threshold changed by the accuracy threshold change unit for each subject.

14. an input device for a user to perform an input operation; 14. The image processing device according to claim 1, further comprising a manual change unit that changes the certainty threshold value based on an input operation via the input device.

15. Analyzing a plurality of frames of ultrasound images of a subject for each frame to calculate the accuracy of blood vessels in the ultrasound images; Detecting the blood vessels where the likelihood is greater than a likelihood threshold; Varying the certainty threshold based on a plurality of the certainties. A method for controlling an image processing device.

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