JP4891590B2 - Ultrasonic Doppler measurement device and Doppler signal processing program - Google Patents

Description

  The present invention relates to an ultrasonic Doppler measurement apparatus and a Doppler signal processing program for measuring flow velocity information of blood flow in a living body, information on movement of a tissue, and the like using an ultrasonic Doppler effect.

  The ultrasonic diagnostic apparatus radiates an ultrasonic pulse generated from an ultrasonic transducer incorporated in an ultrasonic probe into a subject, and generates an ultrasonic reflected wave generated by a difference in acoustic impedance of the subject tissue. It is received by the child and displayed on the monitor. This diagnostic method is widely used for functional diagnosis and morphological diagnosis of various organs of a living body because a real-time two-dimensional image can be easily observed with a simple operation by simply bringing an ultrasonic probe into contact with the body surface. Ultrasound diagnostic methods for obtaining biological information from reflected waves from tissues or blood cells in a living body have made rapid progress with the development of two major technologies, the ultrasonic pulse reflection method and the ultrasonic Doppler method. The obtained B-mode image and color Doppler image are indispensable in today's ultrasonic image diagnosis.

  On the other hand, there is a Doppler spectrum method as a method for obtaining blood flow information at an arbitrary observation site of a subject quantitatively and with high accuracy. In this Doppler spectrum method, ultrasonic transmission / reception is performed a plurality of times at regular intervals on the same part of the subject, and ultrasonic waves used for ultrasonic transmission / reception with respect to ultrasonic reflected waves reflected by moving reflectors such as blood cells are used. A Doppler signal is detected by quadrature detection using a reference signal having a frequency substantially equal to the resonance frequency of the vibrator. Then, a Doppler signal at a desired portion is extracted from the Doppler signal by a range gate, and Doppler spectrum data is generated by performing FFT analysis on the extracted Doppler signal.

  Through such a procedure, Doppler spectrum data is continuously generated for Doppler signals obtained from a desired part of the subject, and the Doppler spectrum image data is obtained by sequentially arranging the obtained Doppler spectrum data. Generate. In order to accurately set the range gate at a desired observation site in the subject, the range gate is set under B-mode image observation. At this time, the range gate position is monitored by the B-mode image.

  In Doppler spectrum data obtained by this ultrasonic Doppler measurement device, generally, the vertical axis represents frequency (f), the horizontal axis represents time (t), and the power (strength) of each frequency component is displayed as luminance (gradation). The Various diagnostic parameters are measured based on the Doppler spectrum data. As a representative example, the maximum blood flow rate Vp corresponding to the maximum frequency component fp in the frequency axis direction is detected, and this maximum blood flow rate Vp is detected. There is a method of measuring a diagnostic parameter based on trace waveform data indicating a change in time.

  In the generation of the trace waveform data of the maximum blood flow velocity Vp, a method of measuring the maximum blood flow velocity Vp from the maximum value of the Doppler spectrum component not buried in the noise spectrum is performed, and conventionally the frozen Doppler (stationary display) is performed. The manual trace operation for spectrum data was fundamental.

On the other hand, in recent years, a method for automatically tracing the maximum blood flow velocity Vp based on a predetermined threshold set in the Doppler spectrum data obtained in real time has been developed. A method of automatically setting based on an average noise level has been proposed (see, for example, Patent Document 1). Also proposed is a method of setting a plurality of threshold values in advance and selecting suitable trace waveform data as the trace waveform data of the maximum blood flow velocity Vp from the plurality of trace waveform data generated based on these threshold values. (For example, refer to Patent Document 2).
US Pat. No. 6,528,321 Japanese Patent Laid-Open No. 7-303641

  However, according to the method of the above-mentioned patent document 1, the maximum blood flow velocity Vp may be undetectable due to the influence of noise due to temporal fluctuations in the average signal level and the average noise level. Therefore, a doctor or a laboratory technician (hereinafter referred to as an operator) sequentially updates the threshold value, and sets a threshold value for obtaining desired trace waveform data by observing the trace waveform data generated at this time. Procedure is essential.

  By the way, when the trace waveform data is generated while updating the threshold for the Doppler spectrum data at predetermined intervals, the amount of displacement of the trace waveform data with respect to the amount of change in the threshold depends on the average signal level and the average noise level in the Doppler spectrum data. For example, when the difference between the average signal level and the average noise level (hereinafter referred to as Doppler sensitivity) is large, such as Doppler spectrum data obtained from the blood flow of the common carotid artery, trace waveform data even if the threshold value is slightly changed However, if the Doppler sensitivity is low, such as Doppler spectrum data of the middle cerebral artery or vertebral artery, the trace waveform data is significantly displaced in the frequency axis direction for the same threshold displacement. . In addition, it is known that the Doppler sensitivity depends not only on the measurement site but also on the sex and constitution of the subject (for example, the degree of obesity). In the trace waveform data obtained for such a subject, The same phenomenon as described above occurs.

  FIG. 14A shows trace waveform data when three threshold values are set at predetermined intervals for Doppler spectrum data obtained from the common carotid artery with good Doppler sensitivity, and the vertical axis represents blood flow velocity (frequency), The horizontal axis indicates time. On the other hand, FIG. 14 (b) shows poor Doppler sensitivity, for example, trace waveform data obtained by setting three thresholds at the same interval as in FIG. 14 (a) for Doppler spectrum data of the middle cerebral artery. The vertical axis and the horizontal axis are the same as in FIG.

  Therefore, in order to efficiently select a threshold when desired trace waveform data is generated from a plurality of preset thresholds, the threshold is updated at a relatively small interval with respect to Doppler spectrum data with poor Doppler sensitivity. However, it is desirable to compare and observe the trace waveform data obtained by updating the threshold at relatively large intervals with respect to Doppler spectrum data with good Doppler sensitivity. However, in the method of Patent Document 1 or Patent Document 2 described above, Doppler is used. There is no description about how to set the threshold interval due to the difference in sensitivity.

  The present invention has been made in view of such a conventional problem, and an object of the present invention is to generate a desired trace waveform data by setting a threshold for Doppler spectrum data obtained in time series. A threshold range for the Doppler spectrum data is set based on the spectrum shape model and the Doppler sensitivity, and the desired trace waveform data is updated with high efficiency and high accuracy by sequentially updating a predetermined number of threshold values set in the threshold range. It is an object to provide an ultrasonic Doppler measurement apparatus and a Doppler signal processing program that can be generated by the above.

  In order to achieve the above object, the present invention takes the following measures.

  According to a first aspect of the present invention, there is provided an ultrasonic probe having an ultrasonic transducer that performs ultrasonic transmission / reception in a predetermined direction of a subject, and transmission for transmitting ultrasonic waves by driving the ultrasonic transducer. A unit, a receiving unit for receiving a received signal from the subject obtained by transmitting / receiving the ultrasonic wave, a Doppler signal detecting unit for detecting a Doppler signal for the received signal, and transmitting / receiving an ultrasonic wave in the predetermined direction The threshold range is set for a spectrum data generation unit that generates Doppler spectrum data in time series by repeating the steps, and a predetermined parameter that sets conditions for generating trace waveform data from the Doppler spectrum data. A threshold setting unit for setting a plurality of thresholds in a range; and the threshold corresponding to a threshold selected from the plurality of thresholds A trace data generation unit that generates a temporal change in the Doppler frequency of the spectrum data as the trace waveform data; and a display unit that displays the trace waveform data. The threshold setting unit includes the generated Doppler. The ultrasonic Doppler measurement apparatus is characterized in that the threshold range or the threshold is set based on a waveform of spectrum data.

  According to a second aspect of the present invention, there is provided an ultrasonic probe having an ultrasonic transducer that performs ultrasonic transmission / reception in a predetermined direction of a subject, and transmission for transmitting ultrasonic waves by driving the ultrasonic transducer. A unit, a reception unit that receives a reception signal from the subject obtained by transmission / reception of the ultrasonic wave, a Doppler signal detection unit that detects a Doppler signal from the reception signal, and ultrasonic transmission / reception in the predetermined direction A spectrum data generation unit that generates a Doppler spectrum data in a time series by setting a predetermined window function for the Doppler signal of a predetermined portion obtained in a time series by repeating, and generated by the spectrum data generation unit A Doppler sensitivity measurement unit that measures Doppler sensitivity based on a plurality of the Doppler spectrum data, and the window function Based on the spectrum shape model creation unit for creating a spectrum shape model based on the spectrum shape model and the Doppler sensitivity, a threshold range in which the trace waveform data is displaced by a predetermined amount with respect to the frequency axis direction is set. A threshold setting unit that sets a plurality of thresholds to the threshold, and a trace data generation unit that generates, as the trace waveform data, a temporal change in the Doppler frequency of the Doppler spectrum data corresponding to a threshold selected from the plurality of thresholds. And a display unit for displaying the trace waveform data.

  The third aspect of the present invention is obtained by a transmission function that causes a computer to transmit an ultrasonic wave by driving an ultrasonic transducer that performs ultrasonic transmission / reception in a predetermined direction of the subject, and the transmission / reception of the ultrasonic wave. In addition, a reception function for receiving a reception signal from the subject, a detection function for detecting a Doppler signal with respect to the reception signal, and generation of Doppler spectrum data in time series by repeating ultrasonic transmission and reception in the predetermined direction Doppler spectrum data generation function to be set, and threshold setting function to set a threshold range for a predetermined parameter that sets conditions for generating trace waveform data from Doppler spectrum data, and to set a plurality of threshold values in this threshold range And the Doppler frequency over time of the spectrum data corresponding to a threshold selected from the plurality of thresholds. A time-dependent change generation function for generating a change as the trace waveform data and a display function for displaying the trace waveform data are realized, and the threshold setting function is based on the waveform of the generated Doppler spectrum data. The Doppler signal processing program is characterized in that the threshold range or the threshold is set.

  The fourth aspect of the present invention is obtained by a transmission function that causes a computer to transmit an ultrasonic wave by driving an ultrasonic transducer that performs ultrasonic transmission / reception in a predetermined direction of the subject, and the transmission / reception of the ultrasonic wave. A reception function for receiving a reception signal from the subject, a detection function for detecting a Doppler signal with respect to the reception signal, and a predetermined portion obtained in time series by repeating ultrasonic transmission and reception in the predetermined direction. A spectrum data generation function for generating spectrum data for generating Doppler spectrum data in time series by setting a predetermined window function for the Doppler signal, and measuring Doppler sensitivity based on the plurality of generated Doppler spectrum data Doppler sensitivity measurement function and spectrum shape model that creates a spectrum shape model based on the window function Based on the spectrum shape model creation function to be created, the spectrum shape model and the Doppler sensitivity, a threshold range is set in which the trace waveform data is displaced by a predetermined amount in the frequency axis direction, and a plurality of threshold values are set in this threshold range. A threshold setting function for generating, a trace waveform data generating function for generating a temporal change in the Doppler frequency of the Doppler spectrum data corresponding to a threshold selected from the plurality of thresholds as the trace waveform data, and the trace waveform data A Doppler signal processing program characterized by realizing a display function for displaying.

  As described above, according to the present invention, when generating a desired trace waveform data by setting a threshold for Doppler spectrum data obtained in time series, a threshold range for the Doppler spectrum data based on a spectrum shape model and Doppler sensitivity. And the Doppler signal processing, and the Doppler signal processing, which can generate the desired trace waveform data with high efficiency and high accuracy by sequentially updating a predetermined number of thresholds set in the threshold range A program can be realized.

  Hereinafter, first and second embodiments of the present invention will be described with reference to the drawings. In the following description, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

(First embodiment)
(Device configuration)
In an embodiment of the present invention described below, Doppler sensitivity is measured from the average signal level and average noise level of Doppler spectrum data obtained by ultrasonic transmission / reception with respect to a predetermined part of a subject. Next, a spectrum shape model created based on the window function when generating the Doppler spectrum data described above and a threshold range in which the trace waveform data changes by a predetermined amount in the frequency axis direction based on the Doppler sensitivity are set. A predetermined number of thresholds are set at approximately equal intervals. Then, a threshold value for obtaining desired trace waveform data is selected from the set threshold values, and generation and display of the trace waveform data is continued using the selected threshold value.

  Hereinafter, the configuration of the ultrasonic Doppler measurement device and the basic operation of each unit in the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the ultrasonic Doppler measurement apparatus according to this embodiment, and FIG. 2 is a block diagram of a transmission / reception unit and a data generation unit that constitute the ultrasonic Doppler measurement apparatus.

  An ultrasonic Doppler measurement apparatus 100 shown in FIG. 1 is obtained from an ultrasonic probe 3 that transmits / receives ultrasonic waves to / from a subject, a transmission / reception unit 2 that transmits / receives to / from the ultrasonic probe 3, and a transmission / reception unit 2. A data generation unit 4 that performs signal processing to obtain B-mode data, color Doppler data, and Doppler spectrum data from the received signal, and further, based on the Doppler spectrum data generated by the data generation unit 4 Trace waveform generator 5 for generating trace waveform data of blood flow velocity Vp, and generation of B-mode image data, color Doppler image data, and Doppler spectrum image data from each of the above-mentioned data obtained in time series in data generator 4 And save the trace waveform data generated by the trace waveform generator 5 It has a 憶部 6.

  Further, the ultrasonic Doppler measurement apparatus 100 includes, for example, a reference signal generation unit 1 that generates a continuous wave or a rectangular wave having a frequency substantially equal to the center frequency of the ultrasonic pulse to the transmission / reception unit 2 or the data generation unit 4. A display unit 7 for displaying image data, trace waveform data, and the like stored in the data storage unit 6; input of patient information by the operator; setting of an image display mode; setting of conditions for generating various image data and trace waveform data Furthermore, an input unit 8 for inputting various command signals and the like, and a system control unit 10 for comprehensively controlling the above-described units in the ultrasonic Doppler measurement apparatus 100 are provided.

  The ultrasonic probe 3 performs ultrasonic wave transmission / reception by bringing its front surface into contact with the surface of a subject, and a plurality of (N) micro ultrasonic transducers arranged in a one-dimensional manner. It has at the tip. This ultrasonic transducer is an electroacoustic transducer, which converts electric pulses into ultrasonic pulses (transmitted ultrasonic waves) during transmission, and converts reflected ultrasonic waves (received ultrasonic waves) into electric signals (received signals) during reception. It has the function to convert to. And each of the above-mentioned some ultrasonic transducer | vibrator is connected to the transmission / reception part 2 via the cable which is not shown in figure. The ultrasonic probe 3 has a sector scan support, a linear scan support, a convex scan support, and the like, and is arbitrarily selected according to the diagnostic part. Although the case where the ultrasonic probe 3 for sector scanning is used is described below, the present invention is not limited to this method, and linear scanning or convex scanning may be used.

  Next, the transmission / reception unit 2 illustrated in FIG. 2 generates a drive signal for radiating transmission ultrasonic waves from the ultrasonic probe 3 and phasing addition to the reception signal from the ultrasonic probe 3. The receiving part 22 which performs is provided.

  The transmission unit 21 includes a rate pulse generator 211, a transmission delay circuit 212, and a drive circuit 213. The rate pulse generator 211 divides the continuous wave or the rectangular wave supplied from the reference signal generation unit 1. Thus, a rate pulse for determining the repetition period of the transmission ultrasonic wave is generated, and this rate pulse is supplied to the transmission delay circuit 212.

  The transmission delay circuit 212 is composed of the same number (N channels) of independent delay circuits as the ultrasonic transducers used for transmission, and transmits the transmission ultrasonic waves to a predetermined depth in order to obtain a narrow beam width in transmission. A delay time for convergence and a delay time for radiating transmission ultrasonic waves in a predetermined direction are given to the rate pulse, and this rate pulse is supplied to the drive circuit 213. The drive circuit 213 has an N-channel independent drive circuit, and generates a drive pulse for driving the ultrasonic transducer built in the ultrasonic probe 3 based on the rate pulse.

  On the other hand, the receiving unit 22 includes an A / D converter 221 including N channels, a reception delay circuit 222, and an adder 223. The N-channel reception signal supplied from the ultrasonic probe 3 is converted into a digital signal by the A / D converter 221 and sent to the reception delay circuit 222. The reception delay circuit 222 converts a focusing delay time for focusing an ultrasonic reflected wave from a predetermined depth and a deflection delay time for setting reception directivity in a predetermined direction to an A / D converter. Each of the N-channel reception signals output from 221 is given, and an adder 223 performs phasing addition on the reception signals from these reception delay circuits 222 (adding the phases of the reception signals obtained from a predetermined direction). To do.

  Next, the data generation unit 4 includes a B-mode data generation unit 41 for generating B-mode data for the reception signal output from the adder 223 of the reception unit 22, and quadrature detection for the reception signal. The Doppler signal detection unit 42 that detects the Doppler signal in line, the color Doppler data generation unit 43 that generates the color Doppler data based on the detected Doppler signal, and the spectrum data by frequency analysis of the Doppler signal. A spectrum data generation unit 44 is provided.

  The B-mode data generation unit 41 includes an envelope detector 411 and a logarithmic converter 412. The envelope detector 411 envelope-detects the received signal after the phasing addition supplied from the adder 223 of the reception unit 22. The amplitude of the envelope detection signal is logarithmically converted by a logarithmic converter 412. Note that the envelope detector 411 and the logarithmic converter 412 may be configured in a reversed order.

  On the other hand, the Doppler signal detection unit 42 includes a π / 2 phase shifter 421, mixers 422-1 and 422-2, and LPFs (low-pass filters) 423-1 and 423-2. Quadrature detection is performed on the received signal supplied from the adder 223 of the unit 22 to detect a Doppler signal.

  The color Doppler data generation unit 43 includes a Doppler signal storage circuit 431, an MTI filter 432, an autocorrelation calculator 433, and the like (not shown), and an average blood flow velocity based on the Doppler signal detected by the Doppler signal detection unit 42. Calculate the value and variance. However, in this embodiment, since this unit is not an essential component, detailed description will be omitted.

  Next, the spectrum data generation unit 44 includes an SH (sample hold circuit) 441, an LPF (low-pass filter) 442, a window function setting unit 443, and an FFT (Fast-Fourier-Transform) analyzer 444. The Doppler signal detection unit 42 performs FFT analysis on the Doppler signal. The SH 441 and the LPF 442 are both composed of two channels, and a complex component of the Doppler signal output from the Doppler signal detection unit 42, that is, a real component (I component) and an imaginary component (Q component) are supplied to each channel. Is done.

  Next, basic operations of the Doppler signal detection unit 42 and the spectrum data generation unit 44 that are important components in the generation of Doppler spectrum data of the present invention will be described in more detail with reference to the time chart of FIG. In FIG. 3, for ease of explanation, a case where a Doppler component is detected from an analog reception signal is shown, but actual processing is performed on a digital reception signal output from the reception unit 22.

  3A is a reference signal output from the reference signal generator 1, FIG. 3B is a rate pulse for Doppler spectrum output from the rate pulse generator 211 of the transceiver 2, FIG. 3C shows the received signal after phasing addition obtained from the adder 223 of the receiving unit 22. 3D is a quadrature detection output output from the LPF 423 of the Doppler signal detection unit 42, and FIG. 3E is a diagram for setting the sampling (range gate) position of the SH 441 in the spectrum data generation unit 44. 3 (f) shows the Doppler signal sampled and held by the SH 441, and FIG. 3 (g) shows the Doppler signal in the range gate smoothed by the LPF 442. ing.

  That is, the reception signal (FIG. 3C) output from the reception unit 22 in FIG. 2 is input to the first input terminals of the mixers 422-1 and 422-2 of the Doppler signal detection unit 42. On the other hand, the reference signal (FIG. 3 (a)) of the reference signal generator 1 having a repetition frequency substantially equal to the center frequency of the received signal is directly supplied to the second input terminal of the mixer 422-1 and π / The reference signal whose phase is shifted by 90 degrees in the two-phase shifter 421 is sent to the second input terminal of the mixer 422-2. The outputs of the mixers 422-1 and 422-2 are sent to LPFs 423-1 and 423-2, and the frequency of the received signal supplied from the receiver 22 and the reference signal supplied from the reference signal generator 1. The sum component with the repetition frequency is removed, and only the difference component is extracted as a Doppler signal (FIG. 3D).

  Next, in the SH 441 of the spectrum data generation unit 44, a sampling pulse generated by dividing the Doppler signal output from the LPFs 423-1 and 423-2 and the reference signal of the reference signal generation unit 1 by the system control unit 10 is generated. (Range gate pulse) is supplied (FIG. 3 (e)), and the Doppler signal from a desired distance is sampled and held by this sampling pulse (FIG. 3 (f)). This sampling pulse is generated after the delay time Ts from the rate pulse (FIG. 3B) that determines the timing at which the transmission ultrasonic wave is emitted, and this delay time Ts can be arbitrarily set in the input unit 8. .

  That is, the operator can extract the Doppler signal at the desired distance Lg from the ultrasonic probe 3 by changing the delay time Ts of the sampling pulse. The delay time Ts and the desired distance Lg have a relationship of 2Lg / C = Ts, where C is the sound speed of the subject.

  Next, the stepped noise component superimposed on the Doppler signal of the desired distance Lg output from the SH 441 is removed by the LPF 442 (FIG. 3 (g)), and the window function is set for the smoothed Doppler signal. The unit 443 sets the data length of the Doppler signal in generating the Doppler spectrum data, and further performs a predetermined weighting process on the Doppler signal. Then, the FFT analyzer 444 performs fast Fourier transform on the Doppler signal weighted by the window function setting unit 443 to generate Doppler spectrum data.

  The window function setting unit 443 includes a storage circuit in which coefficient data corresponding to a window shape such as a rectangle, Hanning, and Hamming is stored in advance, and an arithmetic circuit that performs multiplication of the Doppler signal supplied from the LPF 442 and the coefficient data. ing. Then, the arithmetic circuit performs the weighting process based on the above-described window shape on the Doppler signal in the predetermined section extracted based on the data length (observation time width) of the window function set in advance. On the other hand, the FFT analyzer 444 includes an arithmetic circuit and a storage circuit (not shown), and the weighted Doppler signal output from the weighting function setting unit 443 is temporarily stored in the storage circuit. The arithmetic circuit performs FFT analysis on the Doppler signal in a predetermined section stored in the storage circuit to generate Doppler spectrum data.

  FIG. 4 shows a method of generating Doppler spectrum data by the window function setting unit 443 and the FFT analyzer 444. FIG. 4A shows the Doppler signal Ax input to the window function setting unit 443, and FIG. (B) shows the Hanning window shape for Doppler signal components q1 to qm of data length m set in the Doppler signal Ax.

  On the other hand, FIG. 4C shows the Doppler spectrum data B1, B2, B3 obtained by FFT analysis of the Doppler signal in which the window function (that is, the data length m and the Hanning window shape) is set in the weighting function setting unit 443. ... That is, of the discrete Doppler signals (FIG. 4A) supplied from the LPF 442 of the spectrum data generation unit 44, for example, weighting processing and FFT analysis are performed on m Doppler signal components q1 to qm. Thus, first Doppler spectrum data B1 for the spectrum components f1 to fm is generated. Next, m Doppler signal components q1 + j to qm + j after ΔT are subjected to weighting processing and FFT analysis to generate new Doppler spectrum data B2.

  In the same manner, weighting processing and FFT analysis are sequentially performed on m doppler signal components of q1 + 2j to qm + 2j after 2ΔT, q1 + 3j to qm + 3j,. Spectrum data B3, B4,... Are generated. (FIG. 4 (c)). FIG. 4A shows the case where j = 3.

  Returning to FIG. 1, the trace waveform generation unit 5 includes a Doppler sensitivity measurement unit 51, a spectrum shape model generation unit 52, a threshold setting unit 53, and a trace data generation unit 54.

  The Doppler sensitivity measurement unit 51 includes an arithmetic circuit and a storage circuit (not shown), and the time axis direction average of the maximum power in each of a plurality of Doppler spectrum data supplied in time series from the spectrum data generation unit 44 of the data generation unit 4 The value (average signal level) Sa (dB) and noise component frequency axis direction and time axis direction average value (average noise level) Na (dB) are measured, and the difference between the average signal level Sa and the average noise level Na is measured. To measure the Doppler sensitivity Ds (dB).

  FIG. 5 shows Doppler spectrum data having good Doppler sensitivity (FIG. 5A) and Doppler spectrum data having poor Doppler sensitivity (FIG. 5B). The Doppler spectrum data of the artery corresponds to FIG. 5A, and the Doppler spectrum data of the middle cerebral artery corresponds to FIG. 5B. In these Doppler spectrum data, the vertical axis represents power, and the horizontal axis represents frequency (blood flow velocity). The Doppler sensitivity measurement unit 51 measures the average signal level Sa and the average noise level Na and the Doppler sensitivity Ds for each of the Doppler spectrum data having different Doppler sensitivities.

  Note that the noise component of the Doppler spectrum data in FIG. 5A is relatively small with respect to the submaximal in the frequency axis direction generated when Fourier transforming the window function initially set in the input unit 8 and the Doppler signal. It is composed of system noise of a device having a value and a reflected wave component from other than blood cells. On the other hand, the noise component of the Doppler spectrum data in FIG. 5 (b) is constituted by the sub-maximum of the same size as in FIG. 5 (a) and the reflected wave component from other than the system noise and blood cells having a relatively large value. .

  Next, the spectrum shape model creation unit 52 receives the window function information supplied from the system control unit 10 and creates a spectrum shape model by Fourier transforming the window function. FIG. 6 shows a specific example of the spectrum shape model for various window shapes. The rectangular window shape a1, the Hanning window shape a2, and the spectrum shape model in the Hanning window shape shown in FIG. It is shown in b1 to b3 of b).

  On the other hand, the threshold setting unit 53 includes the Doppler sensitivity Ds supplied from the Doppler sensitivity measurement unit 51, the spectrum shape model supplied from the spectrum shape model creation unit 52, and the threshold range and threshold supplied from the system control unit 10. A plurality of thresholds for generating desired trace waveform data are set based on the number information.

  The principle of the threshold setting method in this case will be described with reference to the schematic diagram of FIG. However, the horizontal axis of FIG. 7 corresponds to frequency, and the vertical axis corresponds to power. FIG. 7A illustrates the spectrum shape model MD created by the spectrum shape model creation unit 52 based on the window function information supplied from the system control unit 10 and the Doppler sensitivity Ds supplied from the Doppler sensitivity measurement unit 51. The relative noise level Nr set based on this is shown. However, FIG. 7A shows the case where the Doppler sensitivity is Ds1 (dB) to Ds3 (dB), and the relative noise levels Nr1 to Nr3 in this case are based on the maximum value of the spectrum shape model (0 dB). Are set downward by Ds1 to Ds3.

  FIG. 7B is an enlarged view of the spectrum shape model MD and the relative noise levels Nr1 to Nr3 shown in the broken line frame of FIG. 7A, and each relative noise level Nr1 to Nr3. As a reference, threshold ranges ΔTh1 to ΔTh3 necessary for displacement by a predetermined frequency displacement amount Δf are set. However, ΔTh1 is a threshold range set based on the relative noise level Nr1, and ΔTh2 and ΔTH3 are threshold ranges set based on the relative noise level Nr2 and Nr3. Normally, these threshold ranges ΔTh1 to ΔTh3 correspond to the magnitudes of Doppler sensitivities Ds1 to Ds3 and have a relationship of ΔTh1> ΔTH2> ΔTh3.

  On the other hand, the threshold value setting unit 53 includes K threshold values TL1k, TL2k, and TL3k (k) set in advance in each of the threshold ranges ΔTh1 to ΔTh3 set based on the spectrum shape model MD and the relative noise levels Nr1 to Nr3. = 1 to K) are set at substantially equal intervals. However, although FIG. 7B shows the case of K = 5, it is not limited to this. In the above description, the three relative noise levels Nr1 to Nr3 have been described. For example, when the relative noise level in the Doppler spectrum data obtained from the subject is Nrx, the threshold setting unit 53 is described above. The threshold value TLxk (k = 1 to K) is set by the same procedure.

  Next, the trace data generation unit 54 sequentially sets the threshold value TLxk (k = 1 to K) obtained by the threshold setting unit 53 for the Doppler spectrum data supplied from the spectrum data generation unit 44 of the data generation unit 4. Thus, trace waveform data relating to the maximum blood flow velocity Vp is generated. That is, the trace data generation unit 54 detects the maximum frequency fp based on the threshold value TLxk for each of the plurality of Doppler spectrum data B1, B2, B3,... Obtained by the spectrum data generation unit 44 at ΔT intervals. Furthermore, trace waveform data indicating a temporal change in the maximum blood flow velocity Vp corresponding to the maximum frequency fp is generated. FIG. 8 shows a method for detecting the above-described maximum frequency fp. The maximum frequency fp is the threshold TLxk set by the threshold setting unit 53 and the Doppler spectrum data Bx supplied from the spectrum data generating unit 44. Detected based on intersection.

  Next, the data storage unit 6 in FIG. 1 stores the B mode image data, the color Doppler image data, and the Doppler spectrum based on the B mode data, the color Doppler data, and the Doppler spectrum data obtained in time series in the data generation unit 4. Image data is generated and stored, and the trace waveform data generated in the trace waveform generation unit 5 is stored in correspondence with the Doppler spectrum image data.

  On the other hand, the display unit 7 includes a display data generation circuit, a conversion circuit, and a monitor (not shown). The B-mode image data, the color Doppler image data, the Doppler spectrum image data, and the trace waveform data once stored in the data storage unit 6 are synthesized by the display data generation circuit, and then predetermined Scan conversion is performed, and then D / A conversion and television format conversion are performed in the conversion circuit and displayed on the monitor. At this time, the Doppler spectrum image data and the trace waveform data are superimposed and displayed. For example, the monitor of the display unit 7 displays B-mode image data or an image data display area in which B-mode image data and color Doppler image data are combined and displayed, and a spectrum in which trace waveform data superimposed on Doppler spectrum image data is displayed. A data display area and an incidental information display area in which incidental information such as data collection conditions and display conditions for each piece of data or subject information are displayed are set.

  Next, the input unit 8 is an interactive interface including an input device such as a display panel, a keyboard, a trackball, a mouse, and a selection button on the operation panel. The input unit 8 inputs patient information, sets image data collection conditions, and images. Various command signals such as display mode selection, setting of frequency displacement amount Δf and threshold value number K, and threshold value updating are input. The image display mode includes a B-mode image, a color Doppler image, and a Doppler spectrum image. Further, in the image display mode of the Doppler spectrum image, there is a selection related to the trace waveform data of the maximum blood flow velocity Vp.

  The system control unit 10 includes a CPU and a storage circuit (not shown), and input information, setting information, and selection information input from the input unit 8 by an operator are stored in the storage circuit. On the other hand, the CPU performs overall control of each unit of the ultrasonic Doppler measurement device 100 and control of the entire system based on the above-described information input from the input unit 8.

(Trace waveform data generation and display procedure)
Next, the procedure for generating and displaying the trace waveform data in this embodiment will be described with reference to the flowchart of FIG.

  In the following, a threshold range ΔTh based on the relative noise level Nr of the Doppler spectrum data is set for the spectrum shape model created based on the window function when generating the Doppler spectrum data, and the threshold range ΔTh is set to this threshold range ΔTh. On the other hand, a case where K threshold values TL1 to TLK are set at equal intervals will be described.

  Prior to ultrasonic transmission / reception with respect to the subject, the operator inputs patient information at the input unit 8, sets image data generation conditions, selects an image display mode, and further performs window functions and traces when generating Doppler spectrum data. The frequency displacement amount Δf and the threshold number K at the time of waveform data generation are set, and these input information, setting information, and selection information are stored in the storage circuit of the system control unit 10. In the present embodiment, the B mode image and the Doppler spectrum image display mode are selected as the image display mode, and the trace waveform data display mode of the maximum blood flow velocity Vp is selected (step S1 in FIG. 9).

  When these inputs / selections / settings are completed, the operator fixes the tip of the ultrasonic probe 3 (ultrasonic transmission / reception surface) to a predetermined position on the surface of the subject body, and the first ultrasonic transmission / reception direction (scanning). Ultrasonic transmission / reception for obtaining B-mode data and Doppler spectrum data is performed in the direction θ1). That is, the rate pulse generator 211 in the transmission / reception unit 2 in FIG. 2 determines the repetition period Tr of the ultrasonic pulse radiated into the subject by dividing the reference signal supplied from the reference signal generation unit 1. The rate pulse is generated, and this rate pulse is supplied to the transmission delay circuit 212.

  The transmission delay circuit 212 gives the rate pulse a focusing delay time for focusing the ultrasonic wave to a predetermined depth and a deflection delay time for transmitting the ultrasonic wave in the scanning direction θ1, and drives the rate pulse. This is supplied to the circuit 213. Then, the drive circuit 213 supplies a drive signal generated by the rate pulse to N ultrasonic transducers in the ultrasonic probe 3 via a cable (not shown), and the ultrasonic pulse in the scanning direction θ1 of the subject. Radiate.

  A part of the ultrasonic pulse radiated to the subject is reflected at an interface or tissue between organs having different acoustic impedances. Further, when this ultrasonic wave is reflected by a moving reflector such as a heart wall or blood cell, the ultrasonic frequency is subjected to Doppler shift.

  The ultrasonic reflected wave (received ultrasonic wave) reflected by the tissue or blood cell of the subject is received by the ultrasonic transducer of the ultrasonic probe 3 and converted into an electric signal (received signal). The digital signal is converted by the N-channel independent A / D converter 221 in the unit 22. Further, the reception signal converted into the digital signal is given a predetermined delay time by the reception delay circuit 222, and then added and synthesized by the adder 223 and supplied to the B-mode data generation unit 41 of the data generation unit 4. The

  At this time, in the reception delay circuit 222, a delay time for focusing the ultrasonic reflected wave from a predetermined depth and a delay time for giving a strong reception directivity in the scanning direction θ1 with respect to the ultrasonic reflected wave. It is set by a control signal from the system control unit 10.

  The output signal of the adder 223 supplied to the B-mode data generation unit 41 is subjected to envelope detection and logarithmic conversion, and then stored in a B-mode image data storage area in the data storage unit 6 of FIG.

  Next, the system control unit 10 performs ultrasonic transmission / reception in the scanning direction θ2 to the scanning direction θP in the same procedure, and the B mode data obtained at this time is stored in the B mode image data storage area in the data storage unit 6. Saved in. That is, the B-mode image data storage area of the data storage unit 6 sequentially stores the B-mode data for the scanning directions θ1 to θP, and generates the B-mode image data for one frame.

  On the other hand, the display data generation circuit of the display unit 7 scan-converts the B-mode image data for one frame stored in the data storage unit 6 according to a predetermined display format, and the conversion circuit converts the operation-converted image data D / A conversion and TV format conversion are then performed and displayed on the monitor. Similarly, ultrasonic transmission / reception with respect to θ1 to θP is repeatedly performed, and the obtained B-mode image data is displayed on the display unit 7 in real time.

  Next, the operator uses the input device of the input unit 8 to set a Doppler marker in the θD direction for the B-mode image data of the subject displayed on the monitor of the display unit 7. Then, the range gate is moved to the distance Lg on the Doppler marker to set the measurement site of the Doppler spectrum data (Step S2 in FIG. 9).

  At this time, ultrasonic transmission / reception for obtaining Doppler spectrum data is alternately performed in the repetition period 2Tr with respect to the scanning direction θD, alternately with B-mode ultrasonic transmission / reception in the scanning directions θ1 to θP performed in the repetition period 2Tr. The reception signal output from the device 223 is supplied to the Doppler signal detection unit 42.

  The Doppler signal detection unit 42 detects the two-channel Doppler signal (complex signal) by performing quadrature phase detection on the supplied reception signal in the mixers 422-1 and 422-2 and the LPFs 423-1 and 423-2, and the spectrum data. This is supplied to SH 441 of the generation unit 44. Then, the SH 441 samples and holds the Doppler signal from the range gate position for a predetermined period (for example, 2Tr) based on the sampling pulse of the range gate position Lg supplied from the system control unit 10.

  Further, the Doppler signal at the range gate position obtained in time series from SH 441 by ultrasonic transmission / reception performed in the scanning direction θD with a repetition period of 2Tr is smoothed by LPF 442 and then subjected to Doppler spectrum data by window function setting unit 443. The data length for generating the data and the weighting process for these data are performed and stored in a storage circuit (not shown) of the FFT analyzer 444.

  Next, an arithmetic circuit (not shown) of the FFT analyzer 444 generates Doppler spectrum data by performing FFT analysis on the Doppler signal having a predetermined data length set by the window function setting unit 443. That is, the arithmetic circuit of the FFT analyzer 444 performs FFT analysis using the weighted Doppler signal that is discretely supplied with the data length m, and generates Doppler spectrum data B1 for the frequencies f1 to fm (FIG. 4). reference). Then, the generated Doppler spectrum data B1 is stored in the spectrum data storage area of the data storage unit 6 and is also stored in a storage circuit (not shown) in the Doppler sensitivity measurement unit 51 of the trace waveform generation unit 5.

  Similarly, the FFT analyzer 444 of the spectrum data generation unit 44 performs Doppler spectrum data B2, B3, B4,... With respect to the weighted Doppler signal supplied after ΔT, after 2ΔT, after 3ΔT,.・ Generate time series. Then, it is stored in the spectrum data storage area of the data storage unit 6 to generate Doppler spectrum image data, and is also stored in the storage circuit of the Doppler sensitivity measurement unit 51 (step S3 in FIG. 9).

  The arithmetic circuit of the Doppler sensitivity measurement unit 51 reads a plurality of Doppler spectrum data stored in the storage circuit, measures the average signal level Sa and the average noise level Na, and obtains the obtained average signal level Sa and average noise level. The Doppler sensitivity Ds is measured based on Na (step S4 in FIG. 9).

  On the other hand, the spectrum shape model creation unit 52 of the trace waveform generation unit 5 receives window function information for generating Doppler spectrum data supplied from the system control unit 10, and performs a Fourier transform on the window function to thereby obtain a spectrum shape model. An MD is created (step S5 in FIG. 9).

  Next, the threshold setting unit 53 includes a Doppler sensitivity Ds supplied from the Doppler sensitivity measurement unit 51, a spectrum shape model MD supplied from the spectrum shape model creation unit 52, and a frequency displacement supplied from the system control unit 10. A threshold range ΔTh is set based on the amount Δf (step S6 in FIG. 9), and further, the K thresholds TL1 to TLK are substantially equally spaced in the threshold range ΔTh based on the threshold number K supplied from the system controller 10. (Step S7 in FIG. 9).

  If the threshold values TL1 to TLK are set, the trace data generation unit 54 automatically selects, for example, the threshold value TL1 closest to the average noise level from the threshold values TL1 to TLK supplied from the threshold setting unit 53 (FIG. 9). Step S8). Next, a threshold TL1 is set for each of the Doppler spectrum data supplied in time series from the spectrum data generation unit 44 of the data generation unit 4 to detect the maximum frequency fp, and the maximum corresponding to the maximum frequency fp. Trace waveform data indicating temporal changes in the blood flow velocity Vp is generated (step S9 in FIG. 9). Then, the obtained trace waveform data is supplied to the data storage unit 6 and stored in correspondence with the already stored Doppler spectrum image data.

  Next, the display unit 7 combines the Doppler spectrum image data and the trace waveform data once stored in the data storage unit 6 and converts them into a predetermined display format, and further performs D / A conversion and television format conversion. The information is displayed on the monitor (step S10 in FIG. 9).

  On the other hand, the operator observes the above-mentioned trace waveform data displayed in real time together with the Doppler spectrum image data on the monitor of the display unit 7, and the trace waveform data of the original maximum blood flow velocity Vp is not displayed due to noise or the like. If it is determined, a command signal for updating the threshold value is input from the input unit 8. The trace data generation unit 54 that has received the command signal via the system control unit 10 updates the threshold TL1 to, for example, TL2, and each of the Doppler spectrum data newly supplied from the spectrum data generation unit 44 of the data generation unit 4 A trace waveform data is generated by setting a threshold value TL2.

  Then, the obtained trace waveform data and the Doppler spectrum image data generated in parallel with the trace waveform data are displayed on the monitor of the display unit 7. The updating of the threshold value and the generation and display of the trace waveform data based on the updated threshold value are repeated until the desired trace waveform data is displayed (steps S8 to S10 in FIG. 9).

  If the desired trace waveform data is displayed, the generation of the trace waveform data is continued with the threshold value fixed, and the obtained trace waveform data is displayed on the display unit 7 together with the Doppler spectrum image data (step of FIG. 9). S11). At this time, it is desirable to display B-mode image data generated in parallel with the above-described Doppler spectrum image data and trace waveform data on the display unit 7, and the measurement site can be confirmed by simultaneous display with the B-mode image data. It becomes easy.

  That is, in setting the threshold value in the above-described embodiment, for example, the threshold value closest to the average noise level Na (threshold value TL1 in the above case) is automatically set, and the first trace waveform data is generated and displayed. Next, when updating the trace waveform data, the threshold value TL1 is updated stepwise in the order of the threshold values TL2, TL3... Every time a threshold update command signal is input from the input unit 8. The trace waveform data generated based on the above is displayed in real time on the display unit 7 together with the Doppler spectrum image data.

  However, the threshold automatically set first is not limited to the threshold closest to the average noise level Na. For example, the central threshold among the K thresholds set by the threshold setting unit 53 is the first. It is automatically set, and the operator may instruct to increase or decrease the threshold value by observing the trace waveform data generated based on the threshold value.

  As described above, according to the present embodiment, when generating desired trace waveform data based on Doppler spectrum data obtained by ultrasonic transmission / reception with respect to the measurement site of the subject, the spectrum shape model and the Doppler sensitivity are used. Based on this, a threshold range is set, and a plurality of threshold values set at predetermined intervals in this threshold range are sequentially updated, so that it is possible to efficiently select an optimum threshold value for obtaining desired trace waveform data. FIG. 11 shows a correlation diagram in which the expected value on the frequency axis and the actually measured value obtained by this apparatus are plotted for each time phase. In such a correlation diagram, when there is data on a straight line with an inclination = 45 degrees (that is, when the ratio between the expected value and the actual measurement value is 1), an ideal envelope tracing process is performed. As shown in the figure, the result obtained by the present apparatus has a ratio between the expected value and the actually measured value between approximately 0.9 and 1.1. Therefore, according to the ultrasonic Doppler measurement apparatus, it is possible to efficiently select an optimum threshold value that provides suitable trace waveform data.

  In the selection of the optimum threshold value in the above-described embodiment, the interval between adjacent threshold values is set so that the displacement amount of the trace waveform data, that is, the frequency displacement amount is substantially equal, so regardless of the magnitude of the Doppler sensitivity. Thus, it is possible to set a threshold value for generating desired trace waveform data with high accuracy and in a short time.

  Therefore, not only the diagnostic accuracy and the diagnostic efficiency are improved, but also the burden on the operator can be greatly reduced.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the above-mentioned embodiment, It can change and implement. For example, the spectrum shape model in the above-described embodiment is created based on the window function, but in addition to this window function, ultrasonic wave transmission / reception such as the measurement part of the trace waveform data, the age and disease name of the subject, the range gate width, etc. You may create it in consideration of conditions.

  For example, when the range gate is narrow, a single-frequency Doppler signal is detected, but when the range gate is wide, a Doppler signal having a wideband frequency component is detected. Depends on turbulent / laminar flow. Accordingly, the spectrum shape model creation unit 52 of the trace waveform generation unit 5 first creates a spectrum shape model based on the window function, and then uses the correction coefficient preset based on the above-described conditions to perform the spectrum shape model. It is desirable to correct

  FIG. 10 shows a specific example of a spectrum shape model corrected based on the range gate width and turbulent / laminar flow, and FIG. 10 (a) shows a spectrum shape model when an extremely narrow range gate is used. It is. On the other hand, FIG. 10B shows a spectrum shape model when turbulent flow is measured with a relatively wide range gate, and FIG. 10C shows a spectrum when laminar flow is measured with a relatively wide range gate. A shape model is shown.

  On the other hand, in the above-described embodiment, the spectrum shape model is created based on the window function having the Hanning window shape, but the window function having other window shapes such as a rectangular window shape, a Hamming window shape, and a Gaussian window shape is used. It does not matter.

  Further, although the case where a plurality of threshold values are set at equal intervals in the threshold range ΔTh has been described, the threshold intervals may be unequal intervals. For example, the trace waveform data is displaced at substantially equal intervals in the frequency axis direction. The threshold interval may be set to

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the present embodiment, the threshold range and a plurality of thresholds within the threshold range are set adaptively based on the occurrence rate of the mistrace waveform.

  FIG. 12 is a block diagram of the ultrasonic Doppler measurement device according to the present embodiment. The ultrasonic Doppler measurement apparatus further includes a mistrace waveform generation rate calculation unit 60 in addition to the configuration shown in FIG.

  The data storage unit 5 stores image data generated by the B-mode data generation unit 41, spectrum data generated by the spectrum data generation unit 44, and expected value data for each threshold of the trace waveform obtained by the trace processing.

  As shown in FIG. 13, the mistrace waveform occurrence rate calculation unit 60 evaluates the error of the trace processing based on the image data, spectrum data, and expected value data stored in the data storage unit 6 and is obtained. Based on the error in the trace processing, the occurrence rate of the mistrace waveform for each threshold due to the initial setting or the like is calculated. Note that any method for evaluating the error of the trace processing may be used.

  The system control unit 10 calculates expected value data for each threshold of the trace waveform obtained by the trace processing. Further, the system control unit 10 determines whether or not to change the currently set threshold based on the calculated mistrace occurrence rate. When it is determined that the threshold value is set, the system control unit 10 controls the threshold value setting in the threshold value setting unit 53 so that the mistrace occurrence rate is equal to or less than a certain value (for example, 5% or less). When the mistrace waveform appears inside the expected value waveform of the envelope waveform in the spectrum display, this control is performed so that the threshold value is increased while the mistrace waveform appears outside the expected value waveform. If so, the threshold value is lowered, for example, according to a table stored in the data storage unit 5.

  In accordance with an instruction from the system control unit 10, the threshold setting unit 53 changes and sets the threshold range and a plurality of thresholds within the threshold range so that the mistrace occurrence rate is equal to or less than a certain position.

  According to the configuration described above, when generating desired trace waveform data based on Doppler spectrum data obtained by ultrasonic transmission / reception with respect to the measurement site of the subject, the threshold range is set based on the occurrence rate of the mistrace waveform. By setting and sequentially updating a plurality of threshold values set at predetermined intervals in this threshold range, it is possible to efficiently select an optimum threshold value that provides desired trace waveform data.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Specific examples of modifications are as follows.

  (1) Each function according to each of the above embodiments can also be realized by installing a program for executing the processing in a computer such as a workstation and developing the program on a memory. In particular, the optimization of the threshold value in the generation of the trace waveform data described in each embodiment activates the Doppler signal processing program that realizes the optimization of the threshold value, and each embodiment performs the Doppler signal stored in the storage device. This is realized by executing the processing described in. At this time, a program capable of causing the computer to execute the technique is stored in a recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (CD-ROM, DVD, etc.), or a semiconductor memory. It can also be distributed.

  (2) For example, in each of the above-described embodiments, the configuration in which the threshold value in the trace waveform is controlled according to a predetermined reference in order to obtain the optimum trace waveform has been described. However, without being limited to this, for example, the threshold value remains fixed, the noise level is controlled by adjusting the gain in ultrasonic scanning, the S / N ratio is controlled by adjusting the dynamic range, and the trace waveform. It is also possible to optimize. Moreover, it is good also as a structure which combines the gain and dynamic range adjustment in an ultrasonic scan, and the threshold value control in the trace waveform described in each embodiment.

  In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  As described above, according to the present invention, when generating a desired trace waveform data by setting a threshold for Doppler spectrum data obtained in time series, a threshold range for the Doppler spectrum data based on a spectrum shape model and Doppler sensitivity. And the Doppler signal processing, and the Doppler signal processing, which can generate the desired trace waveform data with high efficiency and high accuracy by sequentially updating a predetermined number of thresholds set in the threshold range A program can be realized.

FIG. 1 is a block diagram showing the overall configuration of the ultrasonic Doppler measurement apparatus according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of the transmission / reception unit and the data generation unit in the first embodiment. FIG. 3 is a time chart showing basic operations of the Doppler signal detection unit and the spectrum data generation unit in the first embodiment. FIG. 4 is a diagram illustrating a method of generating Doppler spectrum data according to the first embodiment. FIG. 5 is a diagram for explaining the average signal level, the average noise level, and the Doppler sensitivity in the Doppler spectrum data of the first embodiment. FIG. 6 is a diagram illustrating a specific example of a window shape and a spectrum shape model in the first embodiment. FIG. 7 is a diagram illustrating the principle of the threshold setting method according to the first embodiment. FIG. 8 is a diagram illustrating a method for detecting the maximum frequency of Doppler spectrum data according to the first embodiment. FIG. 9 is a flowchart showing a procedure for generating and displaying trace waveform data in the first embodiment. FIG. 10 is a diagram showing a modification of the spectrum shape model in the first embodiment. FIG. 11 shows a correlation diagram in which the expected value on the frequency axis and the actually measured value obtained by this apparatus are plotted for each time phase. FIG. 12 is a block diagram of an ultrasonic Doppler measurement device according to the second embodiment. FIG. 13 is a conceptual diagram for explaining a method of calculating a mistrace waveform occurrence rate according to the second embodiment. FIG. 14 is a diagram for explaining problems in the generation of conventional trace waveform data.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Reference signal generation part, 2 ... Transmission / reception part, 3 ... Ultrasonic probe, 4 ... Data generation part, 5 ... Trace waveform generation part, 6 ... Data storage part, 7 ... Display part, 8 ... Input part, 10 ... System Control unit, 21 ... transmission unit, 22 ... reception unit, 41 ... B mode data generation unit, 42 ... Doppler signal detection unit, 43 ... color Doppler data generation unit, 44 ... spectrum data generation unit, 51 ... Doppler sensitivity measurement unit, 52 ... Spectral shape model creation unit, 53 ... Threshold setting unit, 54 ... Trace data generation unit, 100 ... Ultrasonic Doppler measurement device, 211 ... Rate pulse generator, 212 ... Transmission delay circuit, 213 ... Drive circuit, 221 ... A / D converter, 222 ... reception delay circuit, 223 ... adder, 411 ... envelope detector, 412 ... logarithmic converter, 421 ... π / 2 phase shifter, 422 ... mixer, 423, 442 ... L F (low-pass filter), 441 ... SH (sample-hold circuit), 443 ... window function setting unit, 444 ... FFT analyzer

Claims (25)

An ultrasonic probe having an ultrasonic transducer that transmits and receives ultrasonic waves in a predetermined direction of the subject;
A transmission unit for driving the ultrasonic transducer to transmit ultrasonic waves;
A receiving unit for receiving a reception signal from the subject obtained by transmitting and receiving the ultrasonic wave;
A Doppler signal detection unit for detecting a Doppler signal with respect to the received signal;
A spectrum data generation unit that generates Doppler spectrum data in a time series by setting a predetermined window function for a plurality of Doppler signals obtained in a time series by repeating ultrasonic transmission and reception with respect to the predetermined direction;
A spectrum shape model creation unit for creating a spectrum shape model by converting the window function into the frequency domain;
A Doppler sensitivity measurement unit for measuring Doppler sensitivity based on the Doppler spectrum data;
Based on the spectrum shape model and the Doppler sensitivity , a threshold range is set for a predetermined parameter that sets a condition for generating trace waveform data from the Doppler spectrum data, and a plurality of threshold values are set in the threshold range. A threshold setting unit to be set;
A trace data generation unit that generates, as the trace waveform data, a temporal change in the Doppler frequency of the spectrum data corresponding to a threshold selected from the plurality of thresholds;
An ultrasonic Doppler measurement apparatus comprising: a display unit that displays the trace waveform data.   2. The ultrasonic Doppler according to claim 1, wherein the threshold setting unit sets a threshold range in which the trace waveform data is displaced by a predetermined amount in the frequency axis direction, and sets a plurality of thresholds in the threshold range. Measuring device.   The threshold value setting unit sets an interval of threshold values in the threshold value range so that trace waveform data generated based on each of adjacent threshold values is substantially equally spaced in the frequency axis direction. The ultrasonic Doppler measurement apparatus according to 1 or 2. An input unit for inputting an instruction signal for selecting or updating a predetermined threshold value from the plurality of threshold values set by the threshold value setting unit;
The trace data generation unit generates trace waveform data based on the threshold selected or updated by the input unit;
The ultrasonic Doppler measurement apparatus according to any one of claims 1 to 3. Before SL threshold setting unit, based on the Doppler sensitivity and the spectrum shape model, setting the threshold value range trace waveform data is a predetermined amount displaced with respect to the frequency axis direction,
The ultrasonic Doppler measurement apparatus according to claim 1, wherein   6. The super Doppler sensitivity measurement unit according to claim 5, wherein the Doppler sensitivity measurement unit measures the Doppler sensitivity based on an average signal level and an average noise level obtained from a plurality of Doppler spectrum data obtained in time series. Sonic Doppler measurement device.   The Doppler sensitivity measurement unit measures the average signal level from the average value in the time axis direction of the maximum signal component in each of a plurality of Doppler spectrum data obtained in time series, and the frequency axis direction and time axis of the noise component The ultrasonic Doppler measurement apparatus according to claim 5, wherein the average noise level is measured from an average value of directions.   The spectrum shape model creation unit includes a model correction unit, and the model correction unit corrects the spectrum shape model based on at least one of a measurement part of trace waveform data, ultrasonic transmission / reception conditions, and subject information. The ultrasonic Doppler measurement apparatus according to claim 5, wherein:   6. The ultrasonic Doppler according to claim 5, wherein the threshold setting unit sets a relative noise level in the spectrum shape model based on the Doppler sensitivity, and sets the threshold range based on the relative noise level. Measuring device.   6. The ultrasonic Doppler measurement apparatus according to claim 5, wherein the spectrum data generation unit generates the Doppler spectrum data by performing Fourier transform on a Doppler signal in a predetermined section weighted by the window function.   11. The ultrasonic Doppler measurement apparatus according to claim 10, wherein the spectrum data generation unit performs weighting processing based on any one of a rectangular window shape, a Hanning window shape, a Hamming window shape, and a Gaussian window shape. An ultrasonic probe having an ultrasonic transducer that transmits and receives ultrasonic waves in a predetermined direction of the subject;
A transmission unit for driving the ultrasonic transducer to transmit ultrasonic waves;
A receiving unit for receiving a reception signal from the subject obtained by transmitting and receiving the ultrasonic wave;
A Doppler signal detection unit for detecting a Doppler signal from the received signal;
A spectrum data generation unit for generating a Doppler spectrum data in a time series by setting a predetermined window function for the Doppler signal obtained in a time series by repeating ultrasonic transmission and reception with respect to the predetermined direction;
A Doppler sensitivity measurement unit that measures Doppler sensitivity based on the plurality of Doppler spectrum data generated by the spectrum data generation unit;
A spectrum shape model creation unit for creating a spectrum shape model by converting the window function into the frequency domain;
Based on the spectrum shape model and the Doppler sensitivity, a threshold range in which the trace waveform data is displaced by a predetermined amount with respect to the frequency axis direction, and a threshold setting unit that sets a plurality of thresholds in the threshold range;
A trace data generation unit that generates, as the trace waveform data, a temporal change in the Doppler frequency of the Doppler spectrum data corresponding to a threshold selected from the plurality of thresholds;
A display unit for displaying the trace waveform data;
An ultrasonic Doppler measurement device comprising: On the computer,
A transmission function for transmitting an ultrasonic wave by driving an ultrasonic transducer that performs ultrasonic transmission / reception in a predetermined direction of the subject;
A reception function for receiving a reception signal from the subject obtained by transmission and reception of the ultrasonic wave;
A detection function for detecting a Doppler signal with respect to the received signal;
A spectrum data generation function for generating a Doppler spectrum data in a time series by setting a predetermined window function for a plurality of Doppler signals obtained in a time series by repeating ultrasonic transmission and reception for the predetermined direction;
A spectrum shape model creation function for creating a spectrum shape model by converting the window function to the frequency domain;
A Doppler sensitivity measurement unit for measuring Doppler sensitivity based on the Doppler spectrum data;
Based on the spectrum shape model and the Doppler sensitivity , a threshold range is set for a predetermined parameter that sets conditions for generating trace waveform data from the Doppler spectrum data, and a plurality of threshold values are set in the threshold range. A threshold setting function for setting
A temporal change generation function for generating a temporal change in Doppler frequency of the spectrum data corresponding to a threshold selected from the plurality of thresholds as the trace waveform data;
Realizing a display function for displaying the trace waveform data;
A Doppler signal processing program.   14. The Doppler signal processing according to claim 13, wherein in the threshold setting function, a threshold range in which the trace waveform data is displaced by a predetermined amount with respect to the frequency axis direction is set, and a plurality of thresholds are set in the threshold range. program.   The threshold value setting function sets the threshold interval in the threshold range so that trace waveform data generated based on each of the adjacent threshold values is substantially equally spaced in the frequency axis direction. Item 15. A Doppler signal processing program according to Item 13 or 14. On the computer,
Further realizing a receiving function for receiving an instruction signal for selecting or updating a predetermined threshold value from the set threshold values,
In the trace data generation function, generating trace waveform data based on the selected or updated threshold value,
The Doppler signal processing program according to claim 13 or 14. On the computer,
A Doppler sensitivity measurement function for measuring Doppler sensitivity based on the plurality of Doppler spectrum data generated;
A model generation function for creating a spectrum shape model based on the window function;
Further realized,
In the threshold setting function, wherein the spectral shape model based on the Doppler sensitivity, setting a threshold range for the trace waveform data is a predetermined amount displaced with respect to the frequency axis direction,
The Doppler signal processing program according to any one of claims 13 to 16.   The Doppler sensitivity measurement function is characterized in that the Doppler sensitivity is measured based on an average signal level and an average noise level obtained from a plurality of Doppler spectrum data obtained in time series. Doppler signal processing program.   In the Doppler sensitivity measurement function, the average signal level is measured from the average value in the time axis direction of the maximum signal component in each of a plurality of Doppler spectrum data obtained in time series, and the frequency axis direction and time of the noise component are measured. The Doppler signal processing program according to claim 17 or 18, wherein the average noise level is measured from an average value in an axial direction.   The Doppler signal processing program according to any one of claims 17 to 19, wherein the spectrum shape model creation function creates the spectrum shape model by performing Fourier transform on the window function.   21. The spectrum shape model creation function corrects the spectrum shape model based on at least one of a measurement part of trace waveform data, ultrasonic transmission / reception conditions, and subject information. Doppler signal processing program.   23. The threshold value setting function, wherein a relative noise level is set in the spectrum shape model based on the Doppler sensitivity, and the threshold range is set based on the relative noise level. The Doppler signal processing program as described in any one of Claims.   23. The spectrum data generation function generates the Doppler spectrum data by performing Fourier transform on a Doppler signal in a predetermined section weighted by the window function. Doppler signal processing program.   The Doppler signal processing program according to claim 23, wherein the spectrum data generation function performs weighting processing based on any of a rectangular window shape, a Hanning window shape, a Hamming window shape, and a Gaussian window shape. On the computer,
A transmission function for transmitting an ultrasonic wave by driving an ultrasonic transducer that performs ultrasonic transmission / reception in a predetermined direction of the subject;
A reception function for receiving a reception signal from the subject obtained by transmission and reception of the ultrasonic wave;
A detection function for detecting a Doppler signal with respect to the received signal;
A spectrum data generation function for generating spectrum data for generating Doppler spectrum data in time series by setting a predetermined window function for the Doppler signal obtained in time series by repeating ultrasonic transmission / reception in the predetermined direction When,
A Doppler sensitivity measurement function for measuring Doppler sensitivity based on a plurality of the generated Doppler spectrum data;
A spectrum shape model creation function for creating a spectrum shape model by converting the window function to the frequency domain;
Based on the spectrum shape model and the Doppler sensitivity, a threshold value setting function for setting a threshold value range in which the trace waveform data is displaced by a predetermined amount in the frequency axis direction, and setting a plurality of threshold values in the threshold value range,
A trace waveform data generation function for generating, as the trace waveform data, a temporal change in the Doppler frequency of the Doppler spectrum data corresponding to a threshold selected from the plurality of thresholds;
A display function for displaying the trace waveform data;
To realize a Doppler signal processing program.

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