JP2009240699A - Ultrasonic diagnostic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep a maximum MI (Mechanical Index) value of a ROI (Region Of Interest) designated on ultrasonic image data constant before and after changing a transmission condition of an ultrasonic pulse. <P>SOLUTION: A table for showing a relation between an MI value every combination of transmission conditions stored in a storage part 82 which an MI value adjustment part 8 has and a drive voltage, and a table related to a sound pressure distribution corresponding to each scan line of an ultrasonic pulse are used for an MI value calculation part 81 to calculate maximum MI values of ROI before and after changing the transmission conditions of the ultrasonic pulse. Moreover, on the basis of their ratio, the MI values calculation part 81 determines an optimal drive voltage so as to fix the maximum MI values of the ROI before and after changing the transmission conditions of the ultrasonic pulse and a control unit 8 adjusts the drive voltage to its optimal drive voltage. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that can perform ultrasonic imaging while maintaining a specific MI value in a region of interest constant regardless of changes in transmission conditions of ultrasonic pulses. .

  When using an ultrasonic diagnostic apparatus, an MI (Mechanical Index) value, which is an index related to the mechanical influence of ultrasonic waves on a living body, is used to consider a safety aspect for a patient during ultrasonic irradiation. Uses the MI value as a measure of the intensity of transmitted ultrasound during ultrasonic imaging, and performs a safe diagnosis operation on the subject while confirming the MI value.

Conventionally, for the purpose of improving the safety performance to the subject, an ultrasonic diagnostic apparatus having means for keeping the maximum MI value in an acquired ultrasonic image constant regardless of changes in transmission conditions of ultrasonic pulses has been proposed. Has been. (For example, refer to Patent Document 1).
JP-A-7-67877

  One of the imaging methods of the ultrasonic diagnostic apparatus is a method called contrast echo method. This is intended to enhance ultrasonic echoes by administering an ultrasonic contrast agent composed of microbubbles into the blood vessel of the subject.

  For example, in the examination of the heart and abdominal organs, an ultrasonic contrast agent is injected from a vein to enhance the blood flow signal and evaluate the blood flow dynamics.

  However, due to the sensitive nature of the bubbles, the bubbles collapse due to the irradiation of the ultrasonic waves, thereby shortening the contrast effect time. In recent years, persistent and pressure-resistant contrast agents have been developed, but the basic property of collapse phenomenon does not change because the main component is bubbles.

  Conventionally, at the time of examination using the contrast echo method, an operator uses the above-described MI value not only as a degree of influence on a patient but also as a degree of influence on microbubbles in a subject. Therefore, the MI value plays an important role in the contrast echo method.

  For example, if the intensity of the ultrasonic pulse irradiating the subject is too high, that is, if the MI value is too high, the influence on the microbubbles is too strong, leading to the collapse of the microbubbles, and thus the contrast effect by the microbubbles is diminished. As a result, the image quality of the acquired ultrasonic image is degraded.

  If the intensity of the ultrasonic pulse is too low, that is, if the MI value is too low, the influence on the subject or microbubbles is weakened, but the intensity of the reflected ultrasonic echo is also reduced, leading to a reduction in image quality.

  Therefore, the operator adjusts the intensity of the ultrasonic pulse by using the MI value as a guide so that the influence on the microbubbles can be suppressed and an ultrasonic image with higher image quality can be acquired.

  Therefore, in the case of ultrasonic diagnosis using a contrast agent like the contrast echo method, it is preferable to perform imaging while keeping the MI value constant after adjusting the intensity of the ultrasonic pulse to an optimum state.

  However, in the case of the prior art, the maximum MI value in the entire ultrasound image is fixed, and the MI value in the region of interest (hereinafter abbreviated as ROI: Region Of Interest) that the operator pays attention during the inspection is It changes before and after changing the transmission condition of ultrasonic pulses. Therefore, in order to suppress the deterioration of the image quality in the ROI in the ultrasonic image, the operator is suitable for the inspection while visually confirming the image quality in the ROI in the acquired ultrasonic image every time the ultrasonic transmission condition is changed. Therefore, it was necessary to manually adjust the driving voltage of the ultrasonic pulse so that the image quality could be improved.

  The present invention has been made in consideration of such circumstances, and the MI value in the ROI in the acquired ultrasonic image is kept constant regardless of the change in the transmission condition of the ultrasonic pulse. An object of the present invention is to obtain an ultrasonic diagnostic apparatus capable of reducing the burden on an operator and improving work efficiency by suppressing deterioration of image quality.

  In order to achieve the above object, an ultrasonic diagnostic apparatus according to claim 1 of the present invention includes transmission condition setting means for setting at least one of a plurality of transmission conditions related to an ultrasonic pulse transmitted to a subject, Based on the plurality of transmission conditions, an ultrasonic pulse transmitting means for transmitting the ultrasonic pulse to the subject, an ultrasonic echo receiving means for receiving an ultrasonic echo reflected from the subject, and the received ultrasonic Ultrasonic image generation means for generating an ultrasonic image based on a sound echo, ultrasonic image display means for displaying the ultrasonic image, and ROI setting means for setting an ROI for the displayed ultrasonic image MI value determination means for determining an MI value representing the influence of the ultrasonic pulse on the subject based on the plurality of transmission conditions for at least one location of the ROI; A specific MI value determining means for determining an MI value representing an influence of the ultrasonic pulse on the subject in OI, and at least one of the plurality of transmission conditions by the transmission condition setting means; Transmission condition adjusting means for adjusting at least one of the plurality of transmission conditions excluding the transmission condition for changing the setting so as to keep the specific MI value constant when the setting of one transmission condition is changed. It is characterized by that.

  According to the present invention, the MI value in the ROI in the acquired ultrasonic image can be kept constant and the deterioration of the image quality in the ROI can be suppressed regardless of the change in the transmission condition of the ultrasonic pulse. Can be reduced and work efficiency can be improved.

  Hereinafter, the configuration of the ultrasonic diagnostic apparatus 100 in this embodiment will be described with reference to FIGS. 1 to 3 with reference to the drawings.

(Constitution)
In the present embodiment, the MI value in the ROI in the acquired ultrasonic image using a table (see FIG. 3) showing the relationship between the distance from the sound source of the ultrasonic pulse and the sound pressure of the ultrasonic diagnostic apparatus 100. An example of adjusting the specific MI value so as to keep constant will be described.

  The ultrasonic diagnostic apparatus 100 of the present embodiment shown in FIG. 1 transmits a plurality of ultrasonic pulses to an object to be diagnosed and converts ultrasonic echoes reflected in the body of the subject into electrical signals. An ultrasonic probe 1 having an ultrasonic transducer and a drive signal for transmitting an ultrasonic pulse in a predetermined direction of the subject are supplied to each ultrasonic transducer and received and converted by the ultrasonic transducer. A transmitter / receiver 2 that receives an electrical signal of the ultrasonic echo, an ultrasonic data generator 3 that processes the received signal to generate ultrasonic data, and an ultrasonic wave that generates an ultrasonic image using the ultrasonic data An image data generation unit 4 and a display unit 5 for displaying the ultrasonic image data and the like are included.

  Furthermore, an operation unit 6 for setting the transmission conditions of ultrasonic waves to the subject and a limit MI value, an MI value adjusting unit 7 for calculating and controlling MI values in the acquired ultrasonic image, A control unit 8 that performs overall control of each unit is provided.

  The ultrasonic probe 1 is a sector-type electronic scanning ultrasonic probe 1 in this embodiment, and a plurality of ultrasonic transducers are arranged one-dimensionally at the tip thereof. However, the ultrasonic probe 1 is not limited to the sector type electronic scanning type, and may be another scanning type such as a linear type or a convex type, or a mechanical scanning type.

  The transmission / reception unit 2 includes a transmission unit 21 that transmits ultrasonic pulses to a diagnosis target region of a subject, and a reception unit 22 that receives electrical signals of ultrasonic echoes received and converted by an ultrasonic transducer. .

  The ultrasonic data generation unit 3 performs a predetermined process on the reception signal output from the reception unit 22 of the transmission / reception unit 2 to generate B-mode data, and performs ultrasonic transmission / reception in multiple directions of the subject. A data storage unit (not shown) for sequentially storing the obtained B-mode data is provided.

  The ultrasonic image data generation unit 4 includes an image processing unit and an image data storage unit (not shown). The image processing unit converts the B mode data read from the data storage unit in the ultrasonic data generation unit 3 into these B mode data. The ultrasonic image data is generated by arranging based on the transmission / reception direction information added to.

  The display unit 5 includes a display data generation unit, a data conversion unit, and a monitor (not shown). The display data generation unit generates display data by adding incidental information such as subject information. Then, the data converter performs D / A conversion on the display data and displays it on the monitor.

  Further, the display data generation unit of the display unit 5 adds display data of MI value distribution on the ultrasonic image calculated by the MI value adjustment unit 7 described later as additional information to generate display data.

  The operation unit 6 includes an input device such as a display panel, a keyboard, various switches, a selection button, a mouse, and a trackball, and transmits an ultrasonic pulse transmission condition, input of subject information, and ROI on an ultrasonic image. Has the function to set.

  In addition, various switch groups for changing each transmission condition in the ultrasonic wave related to the ultrasonic output level are provided.

  In this embodiment, an MI value is used as an intensity parameter indicating the ultrasonic output level.

  As described above, the MI value is an index related to the mechanical impact of ultrasonic waves on the living body, and is obtained by the following equation (1). However, Pr. 3 (z) is a negative sound pressure (unit: MPa), and fc is a center frequency (unit: MHz).

  MI value = Pr. 3 (z) / √fc (1)

  In this embodiment, the MI value is given as the intensity parameter of the ultrasonic pulse. However, the intensity parameter is not limited to this, and the TI value (the energy absorbed by the living tissue by the ultrasonic irradiation is applied to the living body). The thermal effect (for example, an index related to the tissue temperature rise), Ispta (Spatial Peak Pulse Average Intensity: spatial peak value of the average intensity value within the pulse wave length), and the like may be used as the intensity parameter.

  Further, the operation unit 6 has a function of setting a limit MI value that is a limit value for the MI value.

  The MI value adjusting unit 7 includes an MI value calculating unit 71 and a storage unit 72 as shown in FIG.

  The MI value calculation unit 71 uses the table indicating the relationship between the MI value in the ultrasonic pulse as shown in FIG. 2 and the drive voltage applied to the ultrasonic probe 1 to irradiate the ultrasonic pulse, as described above. Using the value, the driving voltage that determines the limit MI value that is allowed to be transmitted to the subject is determined for each combination of transmission conditions.

  The table shown in FIG. 2 changes a plurality of transmission conditions, changes the drive voltage applied to the ultrasonic transducer of the ultrasonic probe 1 under the conditions for each combination, and irradiates the ultrasonic pulse. The maximum MI value of the ultrasonic pulse is calculated from Equation (1) using the maximum value of the sound pressure data measured in step (b) and the center frequency of the ultrasonic pulse at that time.

  The tables A, B, and C shown in FIG. 2 are obtained under the same transmission conditions (transmission condition combination patterns A, B, and C) other than the transmission focus, which is one of the transmission conditions. However, the present invention is not limited to this, and a table obtained under various conditions by a combination of transmission conditions is provided, such as a table obtained under the same transmission conditions other than the transmission frequency.

  Further, the MI value calculation unit 71 calculates the MI value in the ultrasonic image acquired using the table showing the sound pressure distribution in the irradiation direction of the ultrasonic pulse shown in FIG.

  The tables A, B, and C shown in FIG. 3 are under the same transmission conditions other than the transmission focus, which is one of the transmission conditions (transmission condition combination patterns A, B, and C), as in the table of FIG. Thus, it can be obtained for a deflection angle of 0 ° of the scanning line.

  Not limited to this, as with the table shown in FIG. 2, a table obtained under various conditions by a combination of transmission conditions is provided, such as a table obtained under the same transmission conditions other than the transmission frequency. Yes. Further, FIG. 3 shows a table relating to the deflection angle 0 ° of the scanning line. Regarding other deflection angles, a sound pressure distribution table relating to each scanning line is provided at intervals of 5 ° with respect to the deflection angle of the scanning line. ing. However, the invention is not limited to this. For example, the number of tables may be increased by further reducing the interval between scanning lines where the tables are provided.

  Regarding the calculation method of the MI value, the storage unit 72 uses the table shown in FIG. 3 showing the sound pressure distribution in the irradiation direction of the ultrasonic pulse emitted from the ultrasonic transducer for each combination of various transmission conditions, and the ultrasonic wave. The MI value calculation unit 71 refers to a table corresponding to a desired combination of transmission conditions for each deflection angle.

  Using the table to be referenced, the MI value calculation unit 71 calculates MI values at all points on the ultrasonic scanning line shown in the table for each deflection angle, and in the ultrasonic image acquired from these values. The maximum MI value and the maximum MI value within the ROI are calculated.

  The storage unit 72 stores a table showing the relationship between the MI value and voltage in the ultrasonic waves shown in FIGS. 2 and 3, and a table showing the sound pressure distribution in the irradiation direction of the ultrasonic pulses.

  The control unit 8 includes a main control unit 81 and a scanning control unit 82. The main control unit 81 includes a CPU and a storage circuit (not shown). The storage circuit stores information on the subject input / set / selected by the operation unit 6 and image data collection conditions. Then, the CPU comprehensively controls each unit of the ultrasonic diagnostic apparatus 100 based on the above-described input information, setting information, and selection information.

(Operation)
Next, the operation of the ultrasonic diagnostic apparatus 100 configured as described above will be described with reference to FIGS.

  First, the operation in the initial irradiation of ultrasonic pulses will be described.

  First, the operator sets a transmission condition and a limit MI value related to the ultrasonic pulse irradiated to the subject from the operation unit 6 (step S1 in FIG. 4).

  Here, setting and changing of the transmission focus, which is one of the transmission conditions of the ultrasonic pulse, will be described. The operator can set the transmission focus in the depth direction at intervals of 5 mm in the range of 5 mm to 150 mm from the operation unit 6, and sets the transmission focus at a position of 75 mm at the initial irradiation stage of the ultrasonic pulse. Other transmission conditions are set so as to apply to the combination of pattern A shown in FIGS. In this embodiment, the limit MI value is set to 1.5. This limit MI value is stored in the storage unit 72 of the MI value adjustment unit 7.

  Next, the main control unit 81 selects the table corresponding to the combination of the transmission conditions set in step S1 of FIG. 4 from the table representing the relationship between the MI value and the drive voltage shown in FIG. 7 is selected and referenced from the storage unit 72 (step S2 in FIG. 4).

  Since the combination of the transmission conditions set in step S1 in FIG. 4 is pattern A (transmission focus: 75 mm), the main control unit 81 selects the table of pattern A in FIG.

  The main control unit 81 uses the limit MI value set by the operator with the operation unit 6 in step S1 of FIG. 4 to select a drive voltage corresponding to the limit MI value from the table, thereby limiting the limit drive voltage of the ultrasonic pulse. Is determined (step S3 in FIG. 4).

  Since the limit MI value is set to 1.5 in step S1 in FIG. 4, the drive voltage when the MI value is 1.5 is selected from the table of pattern A in FIG. In the pattern A table of FIG. 2, when MIA5 is 1.5, the corresponding drive voltage V5 is set as the limit drive voltage of the ultrasonic pulse in the transmission condition combination pattern A.

  After that, the main control unit 81 sends an instruction signal to the scanning control unit 82 so as to start irradiation of the ultrasonic pulse to the subject with the limit driving voltage determined in step S3 of FIG. 4, and the scanning control unit 82 The transmitter 21 is driven in accordance with the instruction signal, and an ultrasonic pulse is emitted (step S4 in FIG. 4).

  For example, the driving voltage V5 determined in step S3 in FIG. 4 is applied to each ultrasonic transducer provided in the ultrasonic probe 1, and thereby the subject is irradiated with the ultrasonic pulse. Then, the ultrasonic echo reflected in the subject is received by the receiving unit 22.

  The received signal is subjected to predetermined processing by a signal processing unit included in the ultrasonic data generation unit 3 to generate B-mode data.

  Thereafter, the image processing unit of the ultrasonic image data generation unit 4 arranges the B-mode data based on the information on the transmission / reception direction and generates an ultrasonic image.

  Then, the display data generation unit of the display unit 5 generates display data to which additional information such as the subject information is added. This display data is D / A converted by the data converter and displayed on the monitor. FIG. 5 is a display example of an ultrasonic image. It is also possible to display the maximum MI value on the display screen as supplementary information of the ultrasonic image. The ultrasonic image data is displayed on the monitor in real time.

  The operator uses the operation unit 6 to finely adjust the drive voltage below the limit drive voltage determined in step S3 in FIG. 4 while referring to the ultrasonic image data displayed on the monitor, and The sound image data is set to an image quality optimum for inspection (step S5 in FIG. 4).

  Since the limit drive voltage determined in step S3 in FIG. 4 is V5, the fine adjustment of the drive voltage is performed within a range not exceeding V5. The drive voltage is set to a limit that can continue to exist without being destroyed by the ultrasonic pulse. In this embodiment, the drive voltage is V4 described in the table of FIG.

  Next, an operation for keeping the specific MI value in the ROI constant will be described.

  In the present embodiment, an operation for keeping the maximum MI value among the MI values at a plurality of locations in the ROI as a specific MI value will be described.

  However, the present invention is not limited to this, and as specific MI values, the minimum MI value among the MI values at a plurality of locations of the ROI, the average value of the MI values at the plurality of locations of the ROI, and the range of the MI values at the plurality of locations of the ROI You may use the value etc. which become the center of.

  First, the operator selects the “MI value priority control mode” using the operation unit 6 (step S1 in FIG. 6).

  A selection signal is transmitted from the operation unit 6 to the main control unit 81, and the main control unit 81 selects a control flow (see FIG. 6) of the “MI value priority control mode”.

  Next, the operator sets the ROI in the acquired ultrasonic image using the operation unit 6 (step S2 in FIG. 6).

  For example, the position, shape, and size of the ROI ultrasonic image data are input using an input device provided in the operation unit 6. The input ROI data is sent to the display unit 5, and the ROI is superimposed and displayed on the ultrasonic image based on the sent data.

  As for the position of the ROI, the position may be designated on the ultrasonic image data displayed on the monitor using the trackball of the operation unit 6. As for the shape, a desired shape may be selected from predetermined shapes, or the ROI may be set by specifying each vertex of the ROI on the display screen using a trackball. Furthermore, the size can be changed to a size desired by the operator after the position and shape of the ROI are determined.

  Next, the main control unit 81 selects a table corresponding to each combination pattern of the transmission conditions of ultrasonic pulses at the time when the “MI value priority control mode” is selected from the tables shown in FIGS. The maximum MI value, the MI value of each point, and the maximum MI value of the ROI in the ultrasonic image are determined and stored in the storage unit 72 (step S3 in FIG. 6).

  In this embodiment, the transmission condition combination pattern is set to pattern A (transmission focus: 75 mm) at this time (see step S1 in FIG. 4), and the drive voltage is set to V4 (see step S5 in FIG. 4). Yes.

  Regarding the maximum MI value in the ultrasonic image, the main control unit 81 compares the drive voltage V4 with the table of the pattern A in FIG. 2 and determines the maximum MI value in the ultrasonic image at this time point as MIA4.

  Further, regarding the calculation of the MI value at each point on the ultrasonic image and the MI value at the ROI, the calculation of the MI value on the scanning line (deflection angle 0 °) of the ultrasonic pulse shown in FIG. 7A is taken as an example. I will give you a description.

  First, using the table shown in FIG. 7B referenced from the storage unit 72, the MI value of each point from the sound source to 150 mm at intervals of 5 mm is determined using the above-described equation (1).

  Further, in the table shown in FIG. 7B referred to from the storage unit 72, the position on the image indicating the maximum value in the ROI and its value from among the ultrasonic sound pressures PrA5 to PrA150 at intervals of 5 mm from the sound source are shown. select.

  As shown in FIG. 7C, since the transmission focus of the ultrasonic pulse is set to 75 mm at this time, the ultrasonic sound pressure PrA75 when the distance from the sound source is 75 mm is the maximum value on the ultrasonic image. And the maximum value within the ROI. Therefore, the maximum MI value within the ROI is calculated on the scanning line with a deflection angle of 0 ° using the sound pressure PrA75.

  In the above-described procedure, the maximum MI value in each ROI is calculated on all ultrasonic scanning lines.

  The maximum MI value in the ROI on all the scanning lines calculated, that is, the maximum MI value MIa in the ROI in the entire ultrasonic image is determined.

  As shown in FIG. 8C, even when the sound pressure distribution shows a peak value outside the ROI, the same processing as in the case where the peak value is shown in the ROI (see FIG. 7C) is performed. .

  Next, the operator uses a switch for changing various transmission conditions provided in the operation unit 6 to change the transmission frequency, transmission focus, etc., which are parameters of the ultrasonic pulse irradiated to the subject. A desired transmission condition is selected, and further desired values are selected from predetermined options (step S4 in FIG. 6).

  In the present embodiment, the set value for the transmission focus is changed from 75 mm to 70 mm in the transmission conditions.

  Here, the following is mentioned as an example of the reason why the operator changes the transmission condition.

  Speaking of changing the transmission frequency, increase the spatial resolution in the ROI of ultrasound image data, increase the frequency to improve the image quality, and improve the sound propagation of the part when you want to inspect a part with a high depth To reduce the frequency.

  Further, in changing the transmission focus, when the desired part and the focus of the ultrasonic pulse do not coincide with each other, the transmission focus position is changed to improve the image quality of the desired part.

  After that, from the tables showing the relationship between the MI value and the drive voltage shown in FIG. 2 and FIG. 3 stored for each combination of various transmission conditions, a table regarding the intensity parameter that matches the set combination of the transmission conditions. Reference is made (step S5 in FIG. 6).

  When the combination pattern of transmission conditions after changing the transmission conditions is pattern B (transmission focus: 70 mm), the main control unit 81 refers to the table of pattern B from the storage unit 72 (see FIGS. 2 and 3).

  Next, the MI value calculation unit 71 uses the tables shown in FIGS. 2 and 3 to determine the maximum MI value in the ultrasound image, the MI value at each point, and the maximum MI value in the ROI in the transmission pattern combination pattern after the change. Is temporarily stored and stored in the storage unit 72 (step S6 in FIG. 6).

  In this embodiment, at this time, the transmission condition combination pattern is set to pattern B (transmission focus: 70 mm) (see step S4 in FIG. 6), and the drive voltage is set to V4 (see step S5 in FIG. 4). Yes.

  Regarding the maximum MI value in the ultrasonic image, the main control unit 81 compares the drive voltage V4 with the table of the pattern B in FIG. 2, and determines the maximum MI value in the ultrasonic image at this time point as MIB4.

  Further, regarding the calculation of the MI value of each point on the ultrasonic image and the MI value in the ROI, the calculation of the MI value on the scanning line (deflection angle 0 °) of the ultrasonic pulse shown in FIG. 8A is taken as an example. I will give you a description.

  First, using the table shown in FIG. 9B referenced from the storage unit 72, the MI value of each point from the sound source to 150 mm at intervals of 5 mm is determined using Equation (1).

  Further, in the table shown in FIG. 9B referred to from the storage unit 72, the position on the image indicating the maximum value in the ROI and its value among the ultrasonic sound pressures PrB5 to PrB150 at intervals of 5 mm from the sound source are shown. select.

  As shown in FIG. 9C, since the transmission focus of the ultrasonic pulse is set to 70 mm at this time, the ultrasonic sound pressure PrB70 at a distance of 70 mm from the sound source is the maximum value on the ultrasonic image. And the maximum value within the ROI. Therefore, the maximum MI value in the ROI is calculated on the scanning line with a deflection angle of 0 ° using the sound pressure PrB70.

  In the above-described procedure, the maximum MI value in each ROI is calculated on all ultrasonic scanning lines.

  From the calculated maximum MI values in the ROI on all scanning lines, the maximum MI value in the ROI in the entire ultrasound image, that is, the maximum MI value MIb in the entire ultrasound image is determined.

  As shown in FIG. 8C, when the sound pressure distribution shows a peak value outside the ROI, the same processing as in the case where the peak value is shown in the ROI (see FIG. 9C) is performed. .

  Next, the MI value adjusting unit 7 determines the magnitude relationship between the maximum MI value after changing the transmission condition determined in step S7 of FIG. 6 and the limit MI value stored in the storage unit 72 in step S1 of FIG. Comparison is made (step S7 in FIG. 6).

  Since the limit MI value is set to 1.5 in step S1 of FIG. 4, the MI value adjusting unit 7 sets the maximum MI value MIB4 on the ultrasonic image selected in step S7 of FIG. Determine whether it is higher or less than 1.5. If the maximum MIB value MIB4 is higher than 1.5, the process proceeds to step S9. If the maximum MIB value MIB4 is 1.5 or less, the process proceeds to step S10.

  In the former case, the maximum MI value in the current transmission condition exceeds the limit MI value, and it is necessary to reduce the MI value in the ultrasonic image data, and accordingly the MI value in the ROI also decreases. The operator is warned (step S8 in FIG. 6).

  An example of a warning method for an operator by display on a monitor will be described.

  When the MI value adjusting unit 7 determines that the maximum MI value exceeds the limit MI value in step S8 of FIG. 6, a warning signal is sent from the MI value adjusting unit 7 to the display unit 5, and the display unit 5 Follow the instructions to display a warning message on the display screen.

  After the warning to the operator, the main control unit 81 shifts the operation flow to step S4 in FIG. 6, and the operator again changes the transmission condition of the ultrasonic pulse.

  If the maximum MI value on the latter ultrasonic image is lower than the limit MI value, the drive voltage is adjusted to match the maximum MI value in the ROI before and after changing the transmission condition (step S9 in FIG. 6).

  The MI value calculation unit 71 calculates the maximum MI value MIb in the ROI on the ultrasonic image after the transmission condition change calculated in step S7 in FIG. 6 and the transmission saved in the storage unit 72 in step S2 in FIG. MI value data included in the ROI set in step S3 in FIG. 6 is selected from the MI values for each point on the ultrasonic image before the condition change, and the maximum value among them, that is, the maximum MI in the ROI is selected. Each value MIa is read, and the ratio r thereof is calculated from the following equation (2).

  r = MIb / MIa (2)

  Using the calculated ratio r and the limit driving voltage V4 (VL in the following equation (3)) after the transmission condition change stored in step S6 of FIG. 6, the MI value calculation unit 71 allows the allowance before and after the transmission condition change. A new drive voltage VN for matching the maximum MI value in the ROI that can be calculated is calculated by the following equation (3).

  VN = VL × r (3)

  Thereafter, an instruction signal is sent from the main control unit 81 to the scanning control unit 82 so as to change to the driving voltage VN calculated in step S10 of FIG. 6, and the scanning control unit 82 drives the transmission unit 21 according to the instruction signal. Then, the subject is irradiated with ultrasonic waves (step S10 in FIG. 6).

  Thereafter, when it is necessary to change the transmission condition again, the operation flow proceeds to step S4 in FIG. 6 and the transmission condition is changed again (step S11 in FIG. 6).

  If there is no change in the transmission condition, the ultrasonic wave is continuously applied with the same drive voltage (step S12 in FIG. 6).

  Further, during the operation of step S11 in FIG. 6, a region having a certain range of a desired range of values relative to the maximum MI value in the ROI, for example, an MI value that is ± 10% of the maximum MI value of the ROI. Are superimposed on the ultrasonic image data (see FIG. 10).

  The above operation is performed, and the maximum MI value of the ROI that is the specific MI value in the present embodiment is kept constant.

  In this embodiment, processing is performed using a table provided for each combination of ultrasonic pulse transmission conditions as shown in FIGS. 2 and 3, but the present invention is not limited to this, and the relationship is more than these tables. An expression may be created and processing may be performed using the relational expression.

(effect)
By such an ultrasonic diagnostic apparatus 100, the maximum MI value in the ROI on the ultrasonic image data is kept constant before and after the change of the transmission condition affecting the MI value, so that the MI value after the change of the transmission condition is reached. This eliminates the need for readjustment, reduces the burden on the operator, and improves work efficiency.

  Further, by using the ratio of the specific MI value of the ROI before and after the change of the transmission condition, it is possible to easily change the drive voltage so as not to change the specific MI value.

  Also, by using the tables shown in FIGS. 2 and 3, it is possible to calculate the MI value in the ultrasonic image for each combination of transmission conditions with fewer processing procedures.

  Furthermore, by displaying the ROI having a specific MI value fixed on the ultrasonic image, the operator can easily recognize how much of the ultrasonic image data is reliable in terms of image quality.

(Modification)
Next, a modification of the first embodiment will be described with reference to FIG.

  In the case of the first embodiment, as shown in FIGS. 8C and 9C, the sound pressure of the ultrasonic pulse at the boundary line of the ROI is provided in the table used for calculating the MI value. The maximum MI value can be calculated using the sound pressure of the table as it is. However, when the sound pressure of the ultrasonic pulse at the boundary line of the ROI is not provided in the table used for calculating the MI value, it is necessary to approximate using the sound pressure of the table. This modification is described with respect to its specific method.

  The description of the overall configuration of the ultrasonic diagnostic apparatus is omitted since it has been made in the first embodiment.

(Operation)
As shown in FIG. 11A, the sound pressure distribution from the sound source of the ultrasonic pulse included in the table is 5 mm apart, while the distance from the sound source of the ultrasonic pulse to the boundary line of the ROI is 57 mm. The sound pressure of the ultrasonic pulse at the boundary line of the ROI is not provided in the table used for calculating the MI value. In this case, since the sound pressure PrB57 at the point where the distance from the sound source of the ultrasonic pulse is 57 mm is the maximum in the ROI from the graph of the sound pressure distribution in FIG. 11B, the maximum MI value is shown at this point. I guess that. Therefore, the MI value calculation unit 71 determines the sound pressure PrB57 necessary for calculating the maximum MI value in the ROI by using the equation shown in FIG. The calculation is performed using the sound pressures PrB55 and PrB60 of ultrasonic pulses having a distance of 55 mm and a distance of 60 mm across a 57 mm point.

(effect)
By such an ultrasonic diagnostic apparatus 100, the maximum MI value in the ROI on the ultrasonic image data is kept constant before and after the change of the transmission condition affecting the MI value, so that the MI value after the change of the transmission condition is reached. Is not necessary, the burden on the operator can be reduced, work efficiency can be improved, and the maximum MI value can be calculated more accurately in the ROI. The degree of change in the image quality of the ultrasonic image in the ROI before and after the change of the transmission condition in FIG.

1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to Embodiment 1 of the present invention. The figure which shows the table showing the relationship between the drive voltage which the ultrasonic diagnostic apparatus in Example 1 of this invention has and the maximum MI value in the ultrasonic pulse irradiated with the drive voltage according to the combination of transmission conditions. FIG. 3 is a diagram illustrating a table representing a change in the depth direction of a sound pressure distribution on a scanning line with an ultrasonic pulse deflection angle of 0 °, which the ultrasonic diagnostic apparatus according to the first embodiment of the present invention has. 2 is a flowchart showing operations and operations of the ultrasonic diagnostic apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a function of the ultrasonic diagnostic apparatus according to the first embodiment of the present invention that displays an ultrasonic image and accompanying information on a display screen. The flowchart which shows operation and operation | movement at the time of MI value priority control mode in Example 1 of this invention. FIG. 3 is an explanatory diagram of a function of calculating an MI value in an ROI on an ultrasound image that the ultrasound diagnostic apparatus according to the first embodiment of the present invention has. FIG. 3 is an explanatory diagram of a function of calculating an MI value in an ROI on an ultrasound image that the ultrasound diagnostic apparatus according to the first embodiment of the present invention has. FIG. 3 is an explanatory diagram of a function of calculating an MI value in an ROI on an ultrasound image that the ultrasound diagnostic apparatus according to the first embodiment of the present invention has. Explanatory drawing of the function which displays the information regarding the MI value in an ultrasonic image on the display screen which the ultrasonic diagnostic apparatus in Example 1 of this invention has. Explanatory drawing of the function which calculates the MI value in ROI on an ultrasonic image which the ultrasonic diagnostic apparatus in the modification of Example 1 of this invention has.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Ultrasonic diagnostic apparatus 1 Ultrasonic probe 2 Transmission / reception part 21 Transmission part 22 Reception part 3 Ultrasonic data generation part 4 Ultrasonic image data generation part 5 Display part 6 Operation part 7 MI value adjustment part 71 MI value calculation part 72 Storage part 8 Control unit 81 Main control unit 82 Scan control unit

Claims (10)

Transmission condition setting means for setting at least one of a plurality of transmission conditions related to the ultrasonic pulse to be transmitted to the subject;
An ultrasonic pulse transmitting means for transmitting the ultrasonic pulse to the subject based on the plurality of transmission conditions;
An ultrasonic echo receiving means for receiving an ultrasonic echo reflected from the subject;
Ultrasonic image generating means for generating an ultrasonic image based on the received ultrasonic echo;
Ultrasonic image display means for displaying the ultrasonic image;
A region of interest setting means for setting a region of interest for the displayed ultrasound image;
MI value determining means for determining an MI value representing an influence of the ultrasonic pulse on the subject based on the plurality of transmission conditions for at least one location in the region of interest;
Specific MI value determining means for determining a specific MI value representing the influence of the ultrasonic pulse on the subject in the region of interest using the MI value;
When the setting of at least one of the plurality of transmission conditions is changed by the transmission condition setting means, at least one of the plurality of transmission conditions excluding the transmission condition for changing the setting is set as the specific MI. An ultrasonic diagnostic apparatus comprising: transmission condition adjusting means for adjusting a value to be kept constant.   The transmission condition adjusting means adjusts a drive voltage applied to the ultrasonic transducer to transmit the ultrasonic pulse, and further, the transmission condition setting means sets at least one of the plurality of transmission conditions. The drive voltage is adjusted based on the ratio between the specific MI value before changing the transmission condition and the specific MI value when the transmission conditions are not changed after changing the transmission condition. The ultrasonic diagnostic apparatus according to claim 1.   The ultrasonic diagnostic apparatus according to claim 1, wherein the specific MI value is a maximum value among the MI values at a plurality of points in the region of interest.   The ultrasonic diagnostic apparatus according to claim 1, wherein the specific MI value is a minimum value among the MI values at a plurality of points in the region of interest.   The ultrasonic diagnostic apparatus according to claim 1, wherein the specific MI value is an average value of the MI values at a plurality of points in the region of interest.   The ultrasonic diagnostic apparatus according to claim 1, wherein the specific MI value is a central value in a range of the MI values at a plurality of points in the region of interest.   The said MI value determination means uses the table regarding the distance from the sound source of the said ultrasonic pulse, and the sound pressure of the said ultrasonic pulse provided for every combination of these several transmission conditions, It is characterized by the above-mentioned. Ultrasound diagnostic equipment.   The ultrasonic diagnostic apparatus according to claim 1, wherein the MI value determining unit determines the MI value corresponding to each combination of the plurality of transmission conditions.   The ultrasonic diagnostic apparatus according to claim 1, wherein the MI value determining unit determines the MI value on a boundary line of the region of interest.   The region of interest, the specific MI value and a region indicating a predetermined ratio of the specific MI value, a maximum MI value on an ultrasonic image, and a position indicating the maximum MI value on the ultrasonic image, 2. The apparatus according to claim 1, further comprising a unit that superimposes and displays at least one of the specific MI value and a position indicating the specific MI value on the ultrasonic image on the ultrasonic image. Ultrasonic diagnostic equipment.

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