JPH0636800B2 - Ultrasonic diagnostic equipment - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an ultrasonic diagnostic apparatus capable of preventing deterioration of image quality of an ultrasonic image due to a first side lobe of an ultrasonic beam.

[Technical background of the invention and its problems] As one of the basic techniques for constructing an ultrasonic diagnostic image of the heart or the like, a so-called fan-shaped ultrasonic beam is used to scan the ultrasonic beam between ribs in order to suppress the influence of reflection by the ribs. Sector scan schemes are well known and quite common.

Among these sector scan methods, a mechanical sector scan method that mechanically drives an ultrasonic transducer to form an ultrasonic image and a sector scan by driving the ultrasonic transducer according to the phased array antenna driving method are possible. However, the latter is superior to the former in terms of reliability of each component of the ultrasonic probe.

However, in the case of the electronic sector scanning method, if the scanning angle, that is, the sector angle is made large, the height of the main lobe, which is originally important for the ultrasonic beam, is reduced, and the S / N ratio is deteriorated. As a result, the first side lobes catch the reflector and form a false image.

This situation will be described with reference to FIGS. 3 and 4. FIG. 3 shows a point light source transfer function G (f) when the sector angle is zero, that is, when an ultrasonic beam is emitted in the vertical direction from the array surface of the ultrasonic transducers. This point light source transfer function G
Although (f) is used in the field of optics, it can be similarly applied to the case of analyzing the propagation of ultrasonic waves. Now, the individual width of an array of ultrasonic vibrators is a, and each vibrator is The point light source transfer function G (f) can be defined by the following formula (1), where b is the interval of and b is the number of simultaneously driven oscillators.

Where sinc af and sinc cf are sink functions, Is a sach function that can be defined when the delta function repeats at regular intervals. Further, f is the frequency of ultrasonic waves. It is apparent from FIG. 3 that the height of the main rogue m at the center is overwhelmingly higher than the height of the first side lobes g on both sides thereof.

On the other hand, FIG. 4 shows a point light source transfer function G ′ (f) when an ultrasonic beam is emitted in the direction of the sector angle θ,
In this case, the main lobe m is shifted from the center O by fs shown in the following equation (1).

fs = sin θ / λ (1) where λ is the wavelength of the ultrasonic wave.

Comparing the heights of the main lobe m and the first side lobe g shown in FIGS. 3 and 4, the height of the main lobe m decreases as the sector angle θ increases, and the height of the first side lobe g decreases. Will increase. For this reason, in the conventional ultrasonic diagnostic apparatus in which the maximum sector angle is uniformly regulated, although the scanning range up to the maximum sector angle is not actually required, the S / Due to the deterioration of the N ratio, not only imbalance of image quality on the display screen occurs but also false elephant is often formed by the first side lobe.

In the past, in order to suppress these image quality deterioration phenomena, especially when the sector scanning ultrasonic probe is used, the width a, the distance b, and the number of simultaneously driven transducers c are set. Since the angle is not determined for each ultrasonic probe but is uniformly regulated by the ultrasonic diagnostic apparatus main body, it is possible to change the ultrasonic probe according to various conditions such as the diagnostic purpose and the diagnostic site. In this case, there is a problem in that the image quality is deteriorated as described above depending on the newly used ultrasonic probe.

Note that this problem can be applied not only to the sector scanning ultrasonic probe but also to the trapezoid scanning ultrasonic probe and the convex scanning ultrasonic probe.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it is possible to automatically and properly set and control the maximum sector angle according to an ultrasonic probe to be used, and to prevent the deterioration of image quality. An object is to provide a sound wave diagnostic apparatus.

[Outline of the Invention] An outline of the present invention for achieving the above object is to provide an ultrasonic image by displaying and displaying an ultrasonic image by providing an ultrasonic probe having an array of transducers and transmitting and receiving ultrasonic waves under predetermined transmission and reception conditions. In the ultrasonic diagnostic apparatus obtained as described above, a storage unit that stores probe information including the width, interval, and number of simultaneously driven transducers of the ultrasonic probe, and an ultrasonic probe based on the probe information. The present invention is characterized by comprising a calculation control means for calculating the maximum sector angle and the number of scanning lines for setting the display range on the display unit and controlling the transmission / reception conditions based on the calculation results.

[Examples of the Invention] Examples of the present invention will be described below. First, the outline of the apparatus of the embodiment shown in FIG. 1 will be described. This apparatus has a timing generator 11 for controlling the whole, and the timing generator 11 drives the ultrasonic transmission / reception control unit 10.

The ultrasonic wave transmission / reception control unit 10 first activates the transmission delay control unit 5 and activates the pulsar 4 to which a high voltage is applied from the high voltage source 3.

Thereby, the ultrasonic probe 1 is passed through the high-voltage switch unit 2.
The excitation signal is transmitted to the ultrasonic probe 1, and the ultrasonic wave delayed by the transmission delay control unit 5 is emitted from the transducer of the ultrasonic probe 1 toward the subject. Then, the ultrasonic wave reflected by the subject enters the transducer of the ultrasonic probe 1, is converted into an echo signal which is an electric signal here, and is sent to the preamplifier section 6 via the high-voltage switch section 2 which is controlled to be switched to the reception state. Is amplified to a predetermined level. Then, this echo signal is subjected to delay processing corresponding to the transmission delay control section 5 in the reception delay control section 7 at the next stage, and then subjected to phasing addition by the adder 8 and signal processing by the receiving circuit 9 and then to the digital scan converter 12. The image is sent and further displayed as an ultrasonic image on the display unit 13.

In FIG. 1, reference numeral 14 denotes an operation panel. The operation panel 14 sends various control signals to the ultrasonic wave transmission / reception control 10 and allows the calculation control means 50, which will be described later, to allow an allowable reduction of the main lobe. The minute m ₀ and the allowable increase amount g ₀ of the first side lobe are sent out by key operation.

Next, the main part of the apparatus of this embodiment will be described in detail. The apparatus according to the present embodiment includes a group of pins required for normal ultrasonic transmission / reception between the ultrasonic probe 1 and the ultrasonic diagnostic apparatus main body, as well as a width a of the vibrator in the ultrasonic probe 1, a gap b, and a simultaneously driven vibrator. The maximum sector angle θmax is calculated based on the connector section 101 that also includes a pin group as a storage unit that stores the probe information consisting of the number c, and the point light source transfer function described above by inputting the probe information from the connector section 101. The calculation control means 50 controls the transmission delay control unit 5 and the reception delay control unit 7 by determining the number of scanning lines that determines the display range based on the maximum sector angle θmax.

The calculation control means 50 inputs probe information including the transducer width a, the spacing b, and the number of simultaneously driven transducers c from the connector unit 101, and based on these values, the transducer array plane is set in the vertical direction (θ = 0), the vertical main lobe calculation unit 102 and the vertical first side lobe calculation unit as first calculation means for calculating the height of the main lobe and the first side lobe of the point light source transfer function when the ultrasonic wave is emitted. 103, and the probe information consisting of the width a, the interval b, and the number c of simultaneously driven vibrators is input, and based on these values and the sector angle θ set by the maximum sector angle determination unit 111 described later, the The θ main lobe calculation unit 107 and the θ first side lobe calculation unit 10 as the second calculation means for calculating the heights of the main lobe and the first side lobe when the ultrasonic wave is emitted at the sector angle θ. 8 and an output and operation panel 14 in units of decibels from the vertical main lobe calculator 102.
The subtractor 104 that inputs the allowable decrease amount m ₀ of the main lobe from
And an output in decibels from the vertical first side lobe 103 and an allowable increase amount g ₀ of the first side lobe from the operation panel 14, and an adder for calculating an allowable maximum first side lobe value based on the input 105 and the subtractor 104
From the θ main lobe calculator 107 to compare the main lobe value at the sector angle θ from the θ main lobe value to determine whether or not the main lobe value is within an allowable range; The maximum allowable first side lobe value from the adder 105 is compared with the first side lobe value at the sector angle θ from the θ first side lobe calculation unit 108 to determine whether the first side lobe value is within the allowable range. A second comparator 109 for determining whether
A gate circuit 110 that opens when at least one of the determination results of the second comparators 106 and 109 is outside the allowable range.
In order to calculate the maximum sector angle θmax, the sector angle θ is increased in predetermined steps, and each time the θ main lobe calculation unit 107 and the θ first side lobe calculation unit 108 are driven, and the gate circuit 110 is opened. A maximum sector angle determination unit 111 that sometimes stops increasing the sector angle θ and sends this value with the sector angle one step before at that time as the maximum sector angle θmax, and the maximum sector angle determination unit 111.
And the display scanning control unit 112 for controlling the transmission delay control unit 5 and the reception delay control unit 7 by calculating the number of operating lines that determines the display range on the display unit 13 based on the output of It has.

As shown in FIGS. 2 (a) and 2 (b), the connector unit 101 as the storage means is composed of a plug CNP and a receptacle CNR, and the plug CNP is the ultrasonic probe 1
Side, that is, the cable side, the receptacle CNP is attached to the housing of the ultrasonic diagnostic apparatus.

In the figures (a) and (b), the numbers ~ respectively represent the pins arranged in correspondence to each other, and these pins are probe information consisting of the width a of the transducers, the interval b, and the number c of simultaneously driven transducers. Used to store. And
The pins from the second plug CNP to the (n-1) th, each one terminal of the resistor _R 2 _~Rn-1 is connected, either the respective other terminals of each resistor _R 2 _~Rn-1 is Is also connected to the first pin. Further, the pins are connected to the pin n.

On the other hand, + V volt is applied to the pin of the receptacle CNR, and the pin is grounded.

The connector section 101 having such a configuration is the plug C
By connecting the NP to the receptacle CNP, the pins of the same number are electrically connected to each other, and as a result, the voltage of + V volt is connected to the plug CNP via the resistors R _{2 to} Rn−1.
Side pin Add.

Therefore, the pin connected to the ground level pin n,
Each pin on the receptacle CNR side that only the ground level The probe information can be stored by the detection.

Next, the operation of the apparatus having the above configuration will be described focusing on the operation of the connector section 101 and the calculation control means 50.

First, when the ultrasonic probe 1 with the plug CNP and the cable is connected to the receptacle CNR attached to the casing of the ultrasonic diagnostic apparatus, the probe information of the width a, the interval b, and the number c of simultaneously driven transducers is excessive. It is recognized by the ultrasonic diagnostic equipment body. In the connector section 101 shown in FIGS. 2A and 2B, only the pins are at the ground level and the other pins are at the + V volt level, but each of the probe information and the voltage level of each pin are previously set. It is assumed that the pattern is associated with.

The vertical main lobe calculation unit 102 and the vertical first side lobe calculation unit 103 of the calculation control unit 50 are based on the point light source transfer function according to the probe information, and the main lobe and the first side of the ultrasonic wave when the sector angle θ = 0. Calculate the lobe height and subtract each result in decibels 1
04 and the adder 105.

The subtractor 104 inputs the value of the main lobe in decibel units and the permissible decrease amount m ₀ thereof, obtains the permissible minimum main lobe value, and sends this to the first comparator 106. Further, the adder 105 inputs the value of the first side lobe in decibel units and the permissible increase amount g ₀ thereof, obtains the maximum permissible first side lobe value, and sends this to the second comparator 109.

On the other hand, the maximum sector angle determination unit 111 sets the sector angle in predetermined steps, and this is set each time by the θ main lobe calculation unit 1
01 or θ to the first side lobe calculation unit 108.

The θ main lobe calculation unit 107 and the θ first side lobe calculation unit 108 respectively input the probe information and the set sector angle, and based on the point light source transfer function, the main lobe value and the first lobe value at the sector angle. One side lobe value is calculated and these results are sent to the first comparator 106 and the second comparator 109, respectively.

The first comparator 106 compares the allowable minimum mainlobe value with the mainlobe value at the set sector angle and determines whether or not the mainlobe value is within the allowable range. Similarly, the second comparator 109 also compares the maximum allowable first side lobe value with the first side lobe value at the set sector angle, and determines whether this first side lobe value is within the allowable range. To do.

The gate circuit 110 keeps the gate off when it is determined that both the determination results of the first comparator 106 and the second comparator 109 are within the allowable range, and as a result, the maximum sector angle determination unit 111 determines The sector angle of the step is set and the θ main lobe calculation unit 10 is operated in the same manner as the above-mentioned operation.
7 and θ The first side lobe calculator 108 is driven. On the other hand, when the first and second comparators 106 and 109 determine that at least one of the main lobe value and the first side lobe value exceeds the allowable range, the gate circuit 110 opens and the maximum sector angle determination unit 111. Send an indication to stop the further increase of the sector angle.

The maximum sector angle determination unit 111 determines the sector angle of the immediately preceding step based on the support from the gate circuit 110 as the maximum sector angle θmax.
Then, the value is sent to the display scan control unit 112. The display operation control unit 112 determines transmission / reception conditions such as the delay time of the transmission delay control unit 5 and the reception delay control unit 7 based on the maximum sector angle θmax and the number of operation lines that determines the display range, and stores the result, and The transmission delay control unit 5 and the reception delay control unit 7 are controlled based on this result.

Although the sector angle θmax increases or decreases depending on the type of ultrasonic probe used for transmitting and receiving ultrasonic waves by the above operation, deterioration of the S / N ratio in the area having a large sector angle on the display unit 13 and the first Virtual image formation due to side lobes can be suppressed.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist thereof.

For example, when the maximum sector angle θmax exceeds 90 °, most of the regions of interest are within the sector angle of 90 °, so the increase of the sector angle in the maximum sector angle determination unit 111 is stopped at 90 °, and the maximum sector angle is increased. It is also possible to set θmax = 90 °.

Further, in the above-mentioned embodiment, even in the case of vertical ultrasonic radiation,
The point light source transfer function was assumed for all ultrasonic radiation at the sector angle θ, and the heights of the main lobe and the first side lobe were calculated based on the point light source transfer function. In this case, since a pulsed point light source is used, a certain correction is required, but it can be sufficiently dealt with by empirical modification of the point light source transfer function.

[Effects of the Invention] According to the present invention described in detail above, although the display range varies depending on the type of ultrasonic probe, deterioration of the S / N ratio at the edge portion having a large sector angle is prevented, and It is possible to provide an ultrasonic diagnostic apparatus capable of preventing the formation of a virtual image due to an increase in one side lobe.

Further, as in the conventional device, the maximum sector angle is uniformly set to 9
Even if the maximum sector angle is small, the frame frequency (the frequency indicating how many screens can be displayed per unit time) can be increased compared to the one that regulates 0 °, and the dynamics of the subject can be further improved. An ultrasonic diagnostic apparatus that can contribute to accurate grasping can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention,
2 (a) and 2 (b) are schematic circuit diagrams showing the pin connection state of the connector part of the same device, and FIG. 3 is a case where ultrasonic waves are radiated vertically from the transducer array surface of the ultrasonic probe. FIG. 4 is a waveform diagram showing a point light source transfer function, and FIG. 4 is a waveform diagram showing a point light source transfer function when ultrasonic waves are emitted from the transducer array surface at a sector angle θ. 1 ... Ultrasonic probe, 13 ... Display part, 50 ... Calculation control part, 101 ... Connector part, 111 ... Maximum sector angle determination part, 112 ... Display scanning control part.

Claims (4)

[Claims] 1. An ultrasonic diagnostic apparatus comprising an ultrasonic probe having an array of transducers for transmitting and receiving ultrasonic waves under a predetermined transmission and reception condition to obtain an ultrasonic image on a display unit. Storage means for storing probe information including the width, interval and number of simultaneously driven transducers of the ultrasonic probe, and setting the maximum sector angle and the display range on the display unit by the ultrasonic probe based on the probe information. An ultrasonic diagnostic apparatus comprising: a calculation control unit that calculates the number of scanning lines and controls the transmission / reception conditions based on these calculation results. 2. The storage means comprises means for storing probe information in a plug connected to the ultrasonic probe side in a connector portion provided between the ultrasonic probe and the ultrasonic diagnostic apparatus main body. The ultrasonic diagnostic apparatus according to claim 1, which is configured by: 3. The calculation control means, when the ultrasonic waves are emitted in a direction perpendicular to the array surface of the transducers based on the probe information and when the ultrasonic waves are emitted at an angle from the array surface. First and second calculating means for calculating the heights of the main lobe and the first side lobe by the light source transfer function, and each of the main lobe and each first side lobe calculated by the first and second calculating means. The maximum sector angle determination unit that sets the maximum sector angle by the ultrasonic probe within the range where the decrease amount and the increase amount of are less than or equal to a predetermined value, and the display for calculating the number of scanning lines on the display unit based on this maximum sector angle. Claim 1 or 2 which has a scanning control part.
The ultrasonic diagnostic apparatus according to the item. 4. The calculation control means calculates an ultrasonic wave transmission / reception timing so as to scan an ultrasonic beam within a range of the maximum sector angle set by the maximum sector angle determination section, and stores the calculation result. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3, further comprising a display control unit having a function.