JP4454293B2 - Ultrasonic diagnostic equipment - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus for a diagnostic site by transmitting an ultrasonic wave into a subject and using a received reflected echo signal, and in particular, automatically gain of an amplifying unit and sensitivity of TGC (time gain compensation). The present invention relates to an ultrasonic diagnostic apparatus having a function of adjusting the frequency.

  As shown in FIG. 8, the conventional ultrasonic diagnostic apparatus has a probe 1 that transmits / receives ultrasonic waves in a subject, drives the probe 1 to transmit ultrasonic waves, and receives received echo signals. The ultrasonic transmission / reception unit 2 that receives the signal, the digital scan converter (DSC) 3 that writes the signal from the ultrasonic transmission / reception unit 2 into a built-in memory, converts the signal into a display coordinate system, and outputs the received signal. An input unit 4, a graphic display unit 5 that performs image display processing, a combining circuit 6 that combines image information of the DSC 3 and the graphic display unit 5, and an image display device 7 that displays an image signal from the combining circuit 6 And an ultrasonic transmission / reception unit 2, a DSC 3, an input unit 4, and a control unit 8 that controls operations of the graphic display unit 5. The ultrasonic transmission / reception unit 2 includes an amplifying unit that amplifies the reflected echo signal uniformly, and a TGC (amplifying the reflected echo signal with sensitivity according to the depth from the body surface in order to compensate for attenuation of the ultrasonic wave in the living body. time gain compensation) section. The input unit 4 includes a gain encoder 9 for the user to set the gain of the amplification unit, and a TGC encoder 10 for the user to set a TGC curve that defines the relationship between the depth and sensitivity of the TGC unit. .

In the conventional ultrasonic diagnostic apparatus, the operator operates the input unit 4 according to the state of the subject (whether it is fat or thin) or where the drawing site is (liver / pancreas / kidney, etc.). The gain and TGC were adjusted. In Patent Document 1, in order to automatically adjust the gain, the number of pixels for each luminance value of an ultrasonic image (so-called B-mode image) of luminance modulation display is graphed, and a luminance distribution histogram is created. There is disclosed a configuration in which a gain value that shifts a peak value of a histogram to a predetermined reference value is obtained and set in an amplifying unit. Patent Document 2 discloses a configuration in which the intensity of a reflected echo signal is obtained in units of ultrasonic scanning lines, an appropriate weighting function is selected in accordance with the intensity, and weighting is performed to change the amplitude of the reflected echo signal. ing. Thereby, in patent document 2, even if it is a weak reflected echo signal, the deterioration of azimuth | direction resolution is suppressed and the effect that the image with a favorable contrast can be obtained is acquired.
Japanese Patent No. 26478771 Japanese Unexamined Patent Publication No. 07-23959

  When the operator adjusts the gain and the TGC curve according to the condition of the subject, it is necessary to perform adjustment for each ultrasonic image until a desired image is obtained, and thus it is difficult to shorten the examination time. In applications that target dozens of subjects per day, such as screening tests for human dogs, etc., it is desired to shorten the test time, but this cannot be met.

  The apparatus described in Patent Document 1 is configured to detect the peak on the assumption that the luminance distribution histogram is a Gaussian distribution. However, the luminance distribution histogram of an ultrasonic image of an actual luminance modulation display is a Gaussian distribution. In many cases, the distribution is such that no peak is detected. For this reason, in the configuration of Patent Document 1, it is thought that many ultrasonic images cannot be automatically set for gain. On the other hand, since the technique described in Patent Document 2 weights the amplitude from the echo signal intensity in units of scanning lines, the effect of improving the azimuth resolution can be obtained, but the gain adjustment of the entire image and the adjustment of the TGC curve can be obtained. Can not do.

  An object of the present invention is to provide an ultrasonic diagnostic apparatus capable of automatically adjusting luminance (gain) or adjusting TGC sensitivity.

  In order to achieve the above object, according to the present invention, an amplification unit that amplifies a signal received by a probe and converts it into a luminance signal, and an image that creates image data using the luminance signal and displays the image data on an image display device An ultrasonic diagnostic apparatus having a creation unit is configured to include means for correcting the amplification factor of the amplification unit. The correction means obtains a cumulative histogram curve of the luminance distribution of the image data, and an amplification factor for shifting a luminance value corresponding to a predetermined cumulative frequency value on the calculated cumulative histogram curve to a predetermined reference luminance value. A correction value is obtained by calculation, and the amplification factor of the amplification unit is corrected.

In another aspect of the present invention, a probe that transmits an ultrasonic beam into a subject within a predetermined scanning range and receives a reflected echo signal sequence, and a received signal received by the probe are In an ultrasonic diagnostic apparatus having an in-vivo attenuation compensation unit that amplifies at an amplification factor according to depth, a storage unit that stores the amplified received signal for each reflected echo signal sequence, and a control unit Means for correcting the amplification factor of the compensation unit for each depth is provided. The amplification factor correction means obtains a correction value for increasing the amplification factor as the signal intensity of the reflected echo signal sequence is smaller, obtains a variance of the signal intensity of the reflected echo signal sequence for each depth, and the dispersion value is predetermined. For a depth smaller than the reference value, there is weighting means for determining a weighting value for decreasing the correction value for each depth. Thus, the amplification factor of the in-vivo attenuation compensation unit is corrected using the correction value weighted by the weighting value for each depth.

An ultrasonic diagnostic apparatus according to an embodiment of the present invention will be described with reference to the drawings.
The configuration of the ultrasonic diagnostic apparatus according to the present embodiment will be described with reference to the block diagram of FIG. The ultrasonic diagnostic apparatus of the present embodiment includes a probe 1, an ultrasonic transmission / reception unit 2, an r-θ memory 11, a digital scan converter (DSC) 3, an xy memory 12, and an input unit 4. A graphic display unit 5, a synthesis circuit 6, an image display device 7, and a control unit 8.

  The probe 1 transmits an ultrasonic beam toward a diagnostic site in a subject and receives a reflected echo signal sequence. Although not shown, the probe 1 is a source of ultrasonic waves inside. A transducer for receiving the reflected echo is arranged. As the probe 1, for example, a sector scanning probe is used which transmits an ultrasonic beam while scanning in a predetermined scanning angle range and receives a reflected echo signal sequence for each scanning angle. .

  The ultrasonic transmission / reception unit 2 transmits a transmission pulse to the probe 1 to generate an ultrasonic wave from the transducer, and an amplifier that amplifies the reception signal of the probe 1 by logarithmic compression or the like 2a and sensitivity (TGC curve) set in accordance with the depth r (time) of the received signal (reflected echo signal sequence) in order to compensate for attenuation of the ultrasonic wave during propagation in the living body (in vivo attenuation compensation) 1 includes a TGC (time gain compensation) circuit 2b, an A / D converter (not shown), and a control circuit (not shown).

  The r-θ memory 11 is a two-dimensional memory for storing the received signal of the ultrasonic transmission / reception unit 2 with respect to the depth r for each scanning line (reflected echo signal sequence of a predetermined scanning angle (θ)). The r-θ memory 11 is configured to be writable and readable. The r-θ memory is subjected to amplification processing, TGC processing, and the like by the ultrasonic transmission / reception unit 2, and the received signal converted into a digital signal is super-high. It is written by the sound wave transmitting / receiving unit 2. The digital scan converter (DSC) 3 reads out the signal stored in the r-θ memory 11 for each scanning line or a plurality of scanning lines and writes it in the built-in line memory, so that an xy coordinate as a display coordinate system is obtained. One frame image data of the system is created and stored in the xy memory 12. Thereby, image data of an ultrasonic tomographic image (so-called B-mode image) is created.

  The input unit 4 is a part that receives an operation by an operator. As shown in FIG. 2, the input unit 4 includes a gain encoder 9 that receives the setting of the amplification factor of the amplifier 2a for adjusting the brightness of the B-mode image, and the TGC circuit 2b. A TGC setting unit 10 for receiving sensitivity settings for each depth section; an input means 41 such as a trackball for receiving settings of various measurement conditions such as an input of a heart rate of a subject and an ultrasonic frequency; A setting unit 43 for setting the type of the touch element 1 and a setting unit 42 for setting the depth of field are included.

  The graphic display unit 5 creates image data for displaying information such as the heart rate and frequency set in the input unit 4. The synthesizing circuit 6 synthesizes the image data stored in the xy memory 12 and the image data created by the graphic display unit 5 and displays them on an image display device 7 such as a CRT. The control unit 8 controls operations of the ultrasonic transmission / reception unit 2, the r-θ memory 11, the digital scan converter 3, the xy memory 12, the input unit 4, the graphic display unit 5, and the synthesis circuit 6.

  In order to display an ultrasonic tomogram that is easy for the operator to recognize and has high resolution, the amplitude of the received signal can be displayed on the image display device 7 by setting an appropriate value as the amplification factor (gain) of the amplifier 2a. In addition, it is desirable to compress the luminance level signal in a range that can be easily recognized by the operator. In addition, in order to obtain an ultrasonic tomographic image in which the attenuation of the ultrasonic wave in vivo is accurately corrected, an appropriate sensitivity (amplification factor) is set in the TGC circuit 2b for each depth in accordance with the attenuation of the ultrasonic wave at the drawing site. It is desirable to do. In the present embodiment, the control unit 8 includes an automatic adjustment unit 8a in order to automatically adjust the gain of the amplifier 2a and the sensitivity of the TGC circuit 2b.

  The automatic adjustment unit 8a obtains an appropriate value by calculation for the gain of the amplifier 2a and the sensitivity for each depth set in the TGC circuit 2b, and sets these values in the amplifier 2a and the TGC circuit 2b. The automatic adjustment unit 8a incorporates a CPU and a memory, and performs automatic gain and TGC curve adjustment operations when the CPU executes a gain calculation program and a TGC curve calculation program stored in the memory in advance.

First, the automatic gain adjustment operation by the automatic adjustment unit 8a will be described with reference to the flowchart of FIG. The gain calculation by the automatic adjustment unit 8a is performed using the image data in the xy memory 12. This is because the image that the operator actually observes on the image display device 7 in real time is equal to the image data stored in the xy memory 12. The automatic adjustment unit 8a first takes in the image data stored in the xy memory 12, and calculates a luminance distribution histogram H (k) indicating the relationship between the luminance value and the number of pixels of the luminance value (step 301, 302). However, k is a luminance value, and it is assumed here that the luminance value is 8 bits (0 to 255). Next, a cumulative histogram AH (k) obtained by accumulating the luminance distribution histogram H (k) is calculated by the following equation (step 303).
AH (k) = H (k) (where k = 0), AH (k) = AH (k-1) + H (k) (where k = 1 to 255)

The obtained cumulative histogram AH (k) is normalized by the following equation to calculate a normalized cumulative histogram NAH (k) (step 304). An example of the normalized cumulative histogram NAH (k) obtained is shown in FIG.
NAH (k) = AH (k) / total number of pixels

  Next, the automatic adjustment unit 8a uses the gain correction value for causing the normalized cumulative histogram curve obtained in step 304 to be a curve that passes the predetermined frequency value PO (pivotOut) and the luminance value PIT (pivotInTarg). Ask for. Specifically, a luminance value PI (pivot In) corresponding to a predetermined frequency value PO is obtained for the normalized cumulative histogram curve obtained in step 304 (step 305). Next, the voltage corresponding to the luminance value PI obtained in step 305 on the graph (FIG. 4B) showing the relationship between the voltage value of the received signal and the luminance value obtained in advance from the characteristics of the amplifier 2 a. A value Vin is obtained (step 306). On the same graph of FIG. 4B, a voltage value VTarg corresponding to a predetermined desired brightness value PIT (pivotInTarg) is obtained (step 307). A gain correction amount necessary for shifting the voltage value Vin obtained here to the voltage value VTarg is obtained by calculation in consideration of the amplification characteristic (for example, logarithmic compression) of the amplifier 2a (step 308). The control unit 8 corrects the gain currently set in the amplifier 2a based on the gain correction amount obtained by the automatic adjustment unit 8a.

  In the normalized cumulative histogram of FIG. 4A obtained for the image data stored in the xy memory 12 by this gain correction, the luminance value corresponding to the frequency value PO is the luminance value PIT (pivotInTarg). Shift to a curve, that is, a curve passing through the coordinates (frequency value PO, luminance value PIT).

  The frequency value PO and the luminance value PIT are coordinates through which a normalized cumulative histogram curve of an ultrasonic tomographic image having a luminance distribution that is easy for an operator to recognize, and values obtained empirically are used. By automatically adjusting the gain of the amplifier 2a so that a normalized cumulative histogram passing through these coordinates can be obtained, an ultrasonic image with a luminance distribution that is easy for the operator to recognize can be displayed without bothering the operator. can do. Further, by using the cumulative histogram, the gain can be automatically adjusted even for an ultrasonic tomographic image in which the histogram curve has a shape having no peak.

  Next, the automatic sensitivity correction operation of the TGC circuit 2b by the automatic adjustment unit 8a will be described with reference to the flowchart of FIG. This correction is performed using the image data in the r-θ memory 11. Here, the description will be made assuming that the number of scanning lines stored in the r-θ memory 11 is N.

First, the signal intensities of N scanning lines are averaged for each depth r, and an average value avr (r) is calculated (step 501). An example of the average value avr (r) is shown in the graph of FIG. The maximum value (avr _max ) and minimum value (avr _min ) of avr (r) obtained in step 501 are calculated, and the maximum value (avr _max ) = 1 and the minimum value (avr _min ) = TGC _min are within the range of avr ( r) is normalized (step 503). Here, TGC _min is a predetermined value in a range of 0 <TGC _min <1, and is introduced so that the minimum value of avr (r) after normalization does not become zero. In order to widen the range of avr (r) after normalization, it is desirable to use a value close to 0 for TGC _min . In the example of FIG. 6B, TGC _min = 0.1.

Next, the variance var (r) is calculated using the average value avr (r) obtained in step 501 (step 503). An example of the variance var (r) is shown in the graph of FIG. Using the obtained dispersion var (r), focusing on the fact that the noise component of the reflected echo signal has a small dispersion value, a function f (r) indicating the level of reliability of avr (r) is created (step 504). ). That determines the equal depth r = r _v a reference value V var (r) is predetermined, 0 ≦ For r ≦ r _v range and f (r) = 1, the _r v _<r ≦ r _e For the range, the reliability function f (r) is created so that f (r) has a predetermined monotonously decreasing curve. However, r _e is the depth of field that is set by the operation of the depth of field setting unit 42 of the input unit 4. The created reliability function f (r) is shown in the graph of FIG. The reliability function f (r), since the depth r is 0 ≦ r ≦ r _v dispersion var (r) value is the reference value V or more for the range of the average value avr (r) is less noise components represents a numeric value 1 that reliable a (reliable = 1) values, for the range of the depth r is deeper than r _{v <r} ≦ r _e than the value of the reference value v of dispersing var (r) A small value less than 1 indicates that the reliability is small and has a large amount of noise components.

Using the normalized average value avr (r) and the predetermined value TGC _min obtained in step 502 and the reliability function f (r) created in step 504, a TGC correction function W (r) is calculated by the following equation ( Step 505).
W (r) = (1- (standardized avr (r)) + TGC _min ) × f (r)

  The TGC correction function W (r) is a function for correcting the attenuation of the signal strength of the current avr (r) so as to obtain a constant strength signal strength, but the reliability function f ( The function weighted by r). The obtained W (r) is shown in the graph of FIG.

  The TGC correction function W (r) obtained in step 505 is averaged for each depth section of the TGC circuit 2b to obtain a TGC sensitivity correction value for each depth section (step 506). The obtained TGC sensitivity correction value is multiplied by the sensitivity of each depth section currently set in the TGC circuit 2b, and the value is set in the TGC circuit 2b as the corrected TGC sensitivity (step 507). As a result, it is possible to compensate for a phenomenon in which the signal intensity of the reflected echo signal train becomes weaker as the depth increases due to attenuation of the ultrasonic wave in the living body, and can be amplified to a constant signal intensity regardless of the depth. At this time, in the present embodiment, since the amplification factor (sensitivity) is not increased by weighting for the depth at which many noise signals are included, the signal strength of the noise signals is suppressed.

  As described above, in the present embodiment, the TGC correction function W (r) for correcting the in-vivo attenuation of the signal intensity is obtained using the data stored in the r-θ memory 11, and therefore the TGC is performed in real time. The sensitivity of the circuit 2b can be corrected. Therefore, the ultrasonic tomogram (B-mode image) displayed in the next image frame displays an image in which the decrease in signal strength due to propagation attenuation in the living body is corrected and the luminance is uniformed in the depth direction. Can do. In addition, since the noise component of the reflected echo signal is weighted by the reliability function f (r), paying attention to the fact that the variance of the signal intensity is small at that time, the signal strength of the noise component is corrected by correcting the TGC sensitivity. Amplification is suppressed. Therefore, an ultrasonic image in which the luminance of the noise signal is suppressed can be displayed.

  As described above, according to the ultrasonic diagnostic apparatus of the present embodiment, the gain adjustment of the amplifier 2a and the sensitivity adjustment of the TGC circuit 2b can be automatically performed for each frame of the ultrasonic image. Therefore, the operator can always make a diagnosis using an image on which gain adjustment and TGC adjustment have been performed.

  In the above-described embodiment, the automatic adjustment unit 8a of the control unit 8 is configured to always automatically correct the gain and TGC sensitivity for each frame. However, the automatic correction unit 8a is configured to perform automatic correction only when instructed by the operator. You can also In this case, as shown in FIG. 7, when the reception unit 13 that receives an automatic correction instruction is added to the input unit 4 and the operator operates the reception unit 13 such as pressing down, the CPU in the automatic adjustment unit 8 a described above. The gain automatic correction program and the TGC automatic correction program are read and executed. Thereby, the control part 8 can always suppress the calculation processing amount.

1 is a block diagram illustrating a schematic configuration of an ultrasonic diagnostic apparatus according to an embodiment of the present invention. It is a front view which shows the front panel of the input part 4 of the ultrasonic diagnosing device of FIG. (A) It is a flowchart which shows the operation | movement of the gain automatic correction | amendment by the automatic adjustment part 8a of this Embodiment, (B) It is a graph which shows an example of the calculated | required cumulative histogram curve. (A) is a graph showing the coordinates (frequency PO, luminance PI) of the cumulative histogram curve in the automatic gain correction by the automatic adjustment unit 8a of the present embodiment, and (B) the voltage value Vin of the amplifier corresponding to the luminance PI. It is a graph to show. It is a flowchart which shows the operation | movement of TGC automatic adjustment by the automatic adjustment part 8a of this Embodiment. (A) It is a graph which shows the example of the average value avr (r) calculated | required by step 501 of FIG. 5, (b) It is a graph which shows the example of normalization avr (r) calculated | required by step 502, (c) (D) A graph showing the reliability function f (r) created in step 504, (e) TGC correction obtained in step 505. It is a graph which shows the example of function W (r). It is a block diagram of the ultrasonic diagnosing device provided with the automatic correction instruction | indication reception part 13 in the input part 4 by another embodiment. It is a block diagram which shows the structure of the conventional ultrasonic diagnostic apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Probe, 2 ... Ultrasonic transmission / reception part, 3 ... Digital scan converter, 4 ... Input part, 5 ... Graphic display part, 6 ... Composition circuit, 7 ... Image display apparatus, 8 ... Control part, 8a ... Automatic adjustment , 9 ... gain encoder, 10 ... TGC encoder, 11 ... r- [theta] memory, 12 ... xy memory, 13 ... automatic correction instruction receiving unit.

Claims (7)

A probe that transmits an ultrasonic beam into a subject and receives a reflected echo signal, an amplifying unit that amplifies the signal received by the probe and converts it into a luminance signal, and an image using the luminance signal An image creation unit that creates data and displays the data on the image display device, and a control unit,
The control unit includes amplification factor correction means for correcting the amplification factor of the amplification unit,
The amplification factor correction means obtains a cumulative histogram curve of the luminance distribution of the image data, and shifts a luminance value corresponding to a predetermined cumulative frequency value on the calculated cumulative histogram curve to a predetermined reference luminance value. An ultrasonic diagnostic apparatus characterized in that a correction value for the amplification factor is obtained by calculation and the amplification factor of the amplification unit is corrected.   2. The ultrasonic diagnostic apparatus according to claim 1, further comprising accepting means for accepting an instruction to start correction from an operator, wherein the amplification factor correcting means performs amplification when the accepting means accepts an instruction to start correction. An ultrasonic diagnostic apparatus characterized by correcting a rate. A probe that transmits an ultrasonic beam into a subject within a predetermined scanning range and receives a reflected echo signal sequence, and a live signal that amplifies the received signal received by the probe at an amplification factor according to the depth of the living body. A body attenuation compensation unit, a storage unit that stores the amplified received signal for each reflected echo signal sequence, and a control unit,
The control unit includes an amplification factor correction means for correcting the amplification factor of the in vivo attenuation compensation unit for each depth,
The gain correction means includes a correction value determination means for determining a correction value for increasing the gain as the signal intensity of the received signal stored in the storage unit for each reflected echo signal sequence is smaller, and the storage The signal intensity variance of the received signal stored for each reflected echo signal sequence is obtained for each depth, and the correction value determining means determines the depth for which the variance value is smaller than a predetermined reference value. Weighting means for determining a weighting value for decreasing the correction value for each depth, and the correction value determining means is a signal intensity of the received signal stored in the storage unit for each reflected echo signal sequence. Is a means for obtaining the average value of each depth, and using the difference between the standardized average value obtained by standardizing the average value and the reference value as the correction value,
The ultrasound diagnostic apparatus, wherein the amplification factor correction means corrects the amplification factor of the in- vivo attenuation compensator using the correction value weighted by the weighting value for each depth.   The ultrasonic diagnostic apparatus according to claim 3, wherein the correction value determination unit obtains an average value of signal strengths of the received signals stored for each of the reflected echo signal sequences in the storage unit for each depth, and The difference between a standardized average value obtained by normalizing the value and a reference value is used as the correction value, and the weighting unit sets the depth where the variance is equal to or greater than the reference value to a weight value of 1, and the variance is smaller than the reference value. An ultrasonic diagnostic apparatus characterized in that a depth is set to a weight value smaller than 1 and the correction value is weighted. A probe that transmits an ultrasonic beam into a subject within a predetermined scanning range and receives a reflected echo signal sequence, and a live signal that amplifies the received signal received by the probe at an amplification factor according to the depth of the living body. A body attenuation compensation unit, a storage unit that stores the amplified received signal for each reflected echo signal sequence, and a control unit,
The control unit includes an amplification factor correction means for correcting the amplification factor of the in vivo attenuation compensation unit for each depth,
The gain correction means includes a correction value determination means for determining a correction value for increasing the gain as the signal intensity of the received signal stored in the storage unit for each reflected echo signal sequence is smaller, and the storage The signal intensity variance of the received signal stored for each reflected echo signal sequence is obtained for each depth, and the correction value determining means determines the depth for which the variance value is smaller than a predetermined reference value. A weighting unit that determines a weighting value for decreasing the correction value for each depth, wherein the weighting unit sets a weighting value of 1 when the variance is equal to or less than a depth at which the variance is a reference value. A depth deeper than the reference value is a weight value that monotonously decreases with depth, and weights the correction value.
The ultrasound diagnostic apparatus, wherein the amplification factor correction means corrects the amplification factor of the in- vivo attenuation compensator using the correction value weighted by the weighting value for each depth. The ultrasonic diagnostic apparatus according to claim 3, wherein an amplification unit that amplifies the entire signal received by the probe with a predetermined amplification factor and converts it into a luminance signal, and the luminance signal is used. An image creation unit that creates image data and displays the image data on an image display device,
The in-vivo attenuation compensation unit further amplifies the signal amplified by the amplification unit according to the depth,
The control unit includes an amplification factor correction means for correcting the amplification factor of the amplification unit,
The amplification factor correction means obtains a cumulative histogram curve of the luminance distribution of the image data, and shifts a luminance value corresponding to a predetermined cumulative frequency value on the calculated cumulative histogram curve to a predetermined reference luminance value. An ultrasonic diagnostic apparatus characterized in that a correction value for the amplification factor is obtained by calculation and the amplification factor of the amplification unit is corrected. The ultrasonic diagnostic apparatus according to any one of claims 3 to 6, further comprising a receiving means for receiving an instruction correction start from an operator, wherein the amplification factor correcting means, the receiving means receives an instruction correction start An ultrasonic diagnostic apparatus that corrects the amplification factor in the event of a failure.

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