JP3944084B2 - Ultrasonic diagnostic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic diagnostic apparatus that sets a transmission delay time.
[0002]
[Prior art]
In an ultrasonic diagnostic apparatus that transmits ultrasonic waves to a living tissue, processes the echo signals, and displays them as, for example, tomographic images, Doppler information, etc., an ultrasonic beam is formed by an ultrasonic transducer composed of a plurality of vibration elements. The ultrasonic beam is scanned electronically. In order to perform this electronic scanning, a transmission signal delayed by a predetermined amount is supplied for each vibration element.
[0003]
FIG. 4 is a block diagram of the transmission unit 10 of the ultrasonic diagnostic apparatus. The transmission unit 10 supplies a transmission drive signal having a transmission delay time corresponding to each of the plurality of vibration elements 12a to 12n of the ultrasonic transducer 11 under the control of a transmission / reception control unit (not shown).
[0004]
In FIG. 4, the first frequency divider 32 has a function of generating a plurality of frequencies by varying the frequency division ratio, and the clock generator 30 is selected according to the frequency division ratio selected under the control of the CPU 36 described later. Is output to the counters 34 a to 34 n as a clock signal 46. For example, when the output of the clock generator 30 is 120 MHz, 40 MHz, 30 MHz, 24 MHz, etc. can be generated as the frequency of the clock signal 46.
[0005]
Each of the counters 34a to 34n is a counter that counts the clock signal 46 input from the first frequency divider 32, a reset terminal that resets the count value by the initialization signal 42, and each delay count value that defines a transmission delay time. Delay count value setting units 40a to 40n. In the delay count value setting units 40a to 40n, the delay count values corresponding to the respective vibration elements 12a to 12n are output and set from the data holding unit 38 under the control of the CPU 36 described later. Each counter 34a to 34n starts counting the clock signal 46 after the initialization signal 42 is input, and outputs a counter output signal 48 when the count value matches the set delay count value.
[0006]
The second frequency divider 58 is a circuit that divides the counter output signal 48 to obtain an intended transmission frequency. The amplifier 60 is a circuit that amplifies the frequency-divided signal and supplies the amplified signal to the vibration elements 12a to 12n as transmission drive signals. By using the second frequency divider 58, the frequency of the clock signal 46 can be increased by that amount, and the resolution of the delay count value can be increased.
[0007]
The CPU 36 has a function as calculation means for calculating each delay count value that defines the transmission delay time of each of the vibration elements 12a to 12n. That is, for each frequency of the clock signal 46 that can be generated by the first frequency divider 32, each delay count value corresponding to each vibration element 12 a to 12 n is calculated and output to the data holding unit 38.
[0008]
The data holding unit 38 stores and holds all the calculated delay count values. For example, each delay count value calculated corresponding to each vibration element 12 a to 12 n is stored and held for each frequency of the clock signal 46. Therefore, if the frequency that can be generated by the first frequency divider 32 is N types such as 40 MHz, 30 MHz, and 24 MHz, the CPU 36 calculates each delay count value for each of the vibration elements 12a to 12n corresponding to the N types of frequencies. The calculation result is stored in the data holding unit 38.
[0009]
The CPU 36 is connected to the first frequency divider 32, the second frequency divider 58, and the data holding unit 38, and the first frequency divider 32 according to the transmission frequency selected by the transmission frequency selection means (not shown). And a function of instructing the frequency division ratio of the second frequency divider 58 and instructing output to the delay count value setting units 40a to 40n of the data holding unit 38. The transmission frequency can be selected by a user input, or may be automatically selected based on a preset criterion, for example, a criterion according to the function switching order of the ultrasonic diagnostic apparatus.
[0010]
In the above configuration of the transmission unit of the conventional ultrasonic diagnostic apparatus, a transmission drive signal having a transmission delay time corresponding to each of the vibration elements 12a to 12n is supplied as follows. For example, when the ultrasonic transmission frequency is selected to be 5 MHz by a transmission frequency selection unit (not shown), the CPU 36 gives an instruction to generate a clock signal 46 having a frequency of 40 MHz to the first frequency divider 32. The second frequency divider 58 is instructed to divide by 1/8. The data holding unit 38 is instructed to output and set the delay count values corresponding to the frequency of 40 MHz to the delay count value setting units 40a to 40n. Thus, each counter 34a to 34n counts the 40 MHz clock signal 46, and when the count value matches the delay count value corresponding to 40 MHz, the counter output signals 48a to 48n are output. Each output signal is frequency-divided to 5 MHz by the second frequency divider 58, amplified by the amplifier 60, and a 5 MHz transmission drive signal having a corresponding transmission delay time is supplied to each of the vibration elements 12a to 12n. .
[0011]
Similarly, when another transmission frequency, for example, a transmission frequency of 3.75 MHz is selected, the first frequency divider 32 and the second frequency divider 58 are given instructions of appropriate frequency division ratios, and data The holding unit 38 is instructed to output each delay count value corresponding to the frequency of the clock signal to each delay count value setting unit 40a to 40n.
[0012]
[Problems to be solved by the invention]
When the delay count number corresponding to each vibration element necessary for electronic scanning is small due to the function of the ultrasonic diagnostic apparatus, the CPU is required to match the speed of electronic scanning without providing a data holding unit. Each delay count can be calculated. In addition, when there are many calculations for each delay count required for electronic scanning and it is difficult for the CPU to calculate each delay count required for the electronic scanning speed, By calculating, storing in the data holding unit, and reading out as necessary, it is possible to obtain each necessary delay count number in accordance with the speed of electronic scanning.
[0013]
By the way, the ultrasonic diagnostic apparatus has a plurality of functions such as a Doppler mode and a color Doppler mode capable of measuring a blood flow velocity using the Doppler effect in addition to the B mode in which a tomographic image of a living tissue can be observed. Things are increasing. Then, diagnosis of a living tissue is performed while switching between the plurality of functions. In this case, since the transmission frequency is selected according to each diagnostic function, it is necessary to switch the transmission frequency according to the switching of the function and to switch the setting of the delay count value in real time corresponding to the switched transmission frequency. .
[0014]
As described above, in order to switch each delay count value in real time, it is necessary to store all of the delay count values used for each function assumed to be switched in the data holding unit and quickly read out according to the switching. .
[0015]
However, the transmission delay time data necessary for electronic scanning is very large. For example, in the case of electronic sector scanning, the transmission delay time for each vibration element is required for each scanning angle (beam address) of electronic scanning, and for each focus position (focus number) to change the focus position. become. In addition, if the configuration of the vibration element of the ultrasonic vibrator is different, the transmission delay time for each vibration element is also different. Data about a case where the highest resolution is required among the functions assumed to be switched must be prepared. For example, with respect to the beam address, it is necessary to prepare data of each transmission delay time for all beam addresses having the finest scanning angle pitch, and the same applies to the focus position, the number of vibration elements, and the like.
[0016]
Moreover, even if the transmission delay time is the same, if the transmission frequency is different, the corresponding delay count value is different, and the data amount of the delay count value to be stored in the data holding unit is N times when there are N types of transmission frequencies. To increase. Therefore, the memory capacity of the data holding unit increases, and a large capacity memory is required. Further, as the memory of the data holding unit increases in capacity, the data read time takes longer and the delay count value cannot be switched quickly.
[0017]
An object of the present invention is to solve the problems of the prior art and to provide an ultrasonic diagnostic apparatus capable of reducing the capacity of a memory for storing a transmission delay time. Another object is to provide an ultrasonic diagnostic apparatus that can quickly set a transmission delay time.
[0018]
[Means for Solving the Problems]
In order to achieve the above object, the ultrasonic diagnostic apparatus according to the present invention is set to count a selected clock selected from a plurality of clocks having different frequencies, and to determine the count value and transmission delay time. When the delay count value matches, a control circuit that outputs the selected clock and generates a transmission pulse of a transmission frequency based on the output, and a transmission drive pulse that is supplied to the ultrasonic transducer based on the transmission pulse An ultrasonic diagnostic apparatus including a transmitter having a transmission circuit that generates a calculation unit that replaces a transmission delay time with a count value of a clock of a reference frequency, and a time indicated by a reference count value as the count value of the selected clock Means for converting and setting the converted count value as a delay count value for determining the transmission delay time, And butterflies.
[0019]
Further, the ultrasonic diagnostic apparatus according to the present invention counts a plurality of vibration elements that transmit and receive ultrasonic waves and a selection clock selected from a plurality of clocks having different frequencies for each of the vibration elements, When the count value matches each delay count value set to determine each transmission delay time corresponding to each vibration element, the selected clock is output, and the transmission frequency is determined based on each output. In the ultrasonic diagnostic apparatus including a transmission unit including a control circuit that generates each transmission pulse and a transmission circuit that generates each transmission drive pulse to be supplied to each vibration element based on each transmission pulse. Calculation means for replacing each transmission delay time with a count value of a reference frequency clock for each element, and a time indicated by a count value of a reference frequency clock for each of the oscillation elements The terms of the count value of the selected clock, characterized in that it comprises means for setting the converted count value as the delay count value for determining the transmission delay time, the.
[0020]
With this configuration, the delay count value corresponding to a frequency other than the reference frequency can be converted from the clock count value of the reference frequency using a conversion means based on linear conversion such as frequency multiplication or frequency division. Only the count value corresponding to the reference frequency needs to be calculated and stored. Therefore, the memory capacity related to the transmission delay time can be reduced.
[0021]
The reference frequency may be any of the plurality of frequencies, and other frequencies may be defined as the reference frequency.
[0022]
The means for converting to the delay count value is a conversion table between the count value of the clock of the reference frequency and the delay count value corresponding to each of the clocks of the plurality of different frequencies, and the frequency of the selected clock And a count value of the reference frequency clock, and a delay count value corresponding to the selected clock is preferably output. The difference between the delay count values corresponding to the same transmission delay time depending on the clock frequency is simply the frequency ratio determined from frequency multiplication or frequency division. Therefore, a conversion table or a memory for converting the ratio between the reference frequency and the selected frequency in correspondence with the count value of the reference frequency clock can be used as the means for converting into the delay count value. For example, a semiconductor memory such as a RAM can be used.
[0023]
Further, it is preferable that the number of bits representing the count value of the reference frequency clock is larger than the number of bits representing the delay count value corresponding to the selected clock. For example, the number of bits representing the count value of the clock of the reference frequency can be used by increasing mbit from the number of bits representing the delay count value corresponding to the selected frequency. m can be selected from integers of 1 or more. Thus, even when the ratio between the reference frequency and the selected frequency is not divisible, the conversion from the count value of the reference frequency clock to the delay count value corresponding to the selected frequency can be performed more accurately.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of the transmission unit 70 of the ultrasonic diagnostic apparatus. Elements common to those in FIG. 4 are denoted by the same reference numerals, and description thereof is omitted.
[0025]
In FIG. 1, a first frequency divider 32 is a frequency dividing circuit having a function of dividing the output of the clock generator 30 in accordance with a frequency dividing ratio selected under the control of the CPU 36 and outputting a clock having a selected frequency. is there. The clock with the selected frequency is input to each of the counters 34 a to 34 n as a clock signal 46. For example, when the output of the clock generator 30 is 120 MHz, the selected frequency is selected from a plurality of frequencies such as 40 MHz, 30 MHz, and 24 MHz that can be divided from 120 MHz.
[0026]
Each of the counters 34a to 34n is a counter that counts the clock signal 46 input from the first frequency divider 32, a reset terminal that resets the count value by the initialization signal 42, and each delay count value that defines a transmission delay time. Delay count value setting units 40a to 40n. In the delay count value setting units 40a to 40n, under the control of the CPU 36, which will be described later, each delay count value corresponding to each vibration element 12a to 12n is output from the conversion table 74 and set. Each counter 34a to 34n starts counting the clock signal 46 after the initialization signal 42 is input, and outputs a counter output signal 48 when the count value matches the set delay count value.
[0027]
The second frequency divider 58 is a circuit that divides the counter output signal 48 to obtain an intended transmission frequency, and the amplifier 60 amplifies the divided signal and supplies it to each of the vibration elements 12a to 12n as a transmission drive signal. It is a circuit to do.
[0028]
The CPU 36 has a function as calculation means for calculating a reference delay count value corresponding to the reference frequency. Here, the reference delay count value is a transmission delay time indicated by a count value of a reference frequency clock. The reference frequency may be determined by selecting one of a plurality of frequencies that can be generated by the first frequency divider 32, or a frequency other than these may be determined as the reference frequency. Since the reference frequency becomes a reference for conversion in a conversion table described later, the higher the frequency, the more accurately the conversion can be performed. For example, 40 MHz can be defined as the reference frequency. The reference delay count value is calculated corresponding to each of the vibration elements 12a to 12n, and the calculation result is output to the reference delay count value holding memory 72 and stored. The reference delay count value holding memory 72 outputs each stored reference delay count value to the conversion table 74 when the conversion table 74 is converted under the control of the CPU 36.
[0029]
Further, the CPU 36 is connected to the first frequency divider 32, the second frequency divider 58, and the conversion table 74, and according to the transmission frequency selected by the transmission frequency selection means (not shown), the first frequency divider 32, It has a function of instructing the frequency division ratio of the second frequency divider 58 and instructing which conversion to use in the conversion table 74. The transmission frequency can be selected by a user input, or may be automatically selected based on a preset criterion, for example, a criterion according to the function switching order of the ultrasonic diagnostic apparatus.
[0030]
The conversion table 74 has a function as conversion means for converting the reference delay count value into a delay count value corresponding to the selected frequency. In other words, under the control of the CPU 36, each reference delay count value output from the reference delay count value holding memory 72 is converted into each delay count value corresponding to the selected frequency, and each converted delay count value is handled. Output to the delay count value setting units 40a to 40n of each counter to be set. When the selected frequency is selected to be the same frequency as the reference frequency, the conversion table 74 does not perform conversion, and outputs and sets the reference delay count value as it is to each delay count value setting unit 40a to 40n of each counter.
[0031]
Even with the same transmission delay time, the delay count value differs depending on the clock frequency, but the difference is simply the frequency ratio due to frequency multiplication or frequency division, and can be easily converted using linear conversion. For example, in the above example, if the reference frequency is 40 MHz and the selected frequency is selected from 30 MHz and 24 MHz, 30/40 is used as a conversion constant for conversion between 40 MHz and 30 MHz, and between 40 MHz and 24 MHz. For conversion, 24/40 is used as a conversion constant. Specific contents of the conversion table 74 will be described later.
[0032]
In the above configuration of the transmission unit of the ultrasonic diagnostic apparatus according to the embodiment of the present invention, a transmission drive signal having a transmission delay time corresponding to each of the vibration elements 12a to 12n is supplied as follows. For example, when the ultrasonic transmission frequency is selected to be 5 MHz by a transmission frequency selection unit (not shown), the CPU 36 gives an instruction to generate a clock signal 46 having a frequency of 40 MHz to the first frequency divider 32. The second frequency divider 58 is instructed to divide by 1/8. If the reference frequency is 40 MHz, the selected frequency is the same as the reference frequency. In this case, the conversion table 74 does not convert the output of the reference delay count value holding memory 72 as it is, for each of the counters 34a to 34n. An instruction to set the delay count value setting units 40a to 40n is issued. Thus, each counter 34a to 34n counts the 40 MHz clock signal 46, and when the count value matches the delay count value corresponding to 40 MHz, the counter output signals 48a to 48n are output. Each output signal is frequency-divided to 5 MHz by the second frequency divider 58, amplified by the amplifier 60, and each oscillation element 12a to 12n is supplied with a 5 MHz transmission drive signal having a corresponding transmission delay time. The
[0033]
Next, when the function of the ultrasonic diagnostic apparatus is switched and the transmission frequency needs to be 3.75 MHz, the CPU 36 gives an instruction to the first frequency divider 32 to generate a clock signal 46 having a frequency of 30 MHz. The second frequency divider 58 is instructed to divide by 1/8. In addition, the conversion table 74 gives an instruction for conversion of 40 MHz-30 MHz. The conversion table 74 converts each reference delay count value output from the reference delay count value holding memory 72 into a delay count value corresponding to 30 MHz by linear conversion of 40 MHz to 30 MHz, and converts the converted value to each counter 34a to 34a. It outputs to 34n delay count value setting part 40a-40n, and sets it. Thus, the counters 34a to 34n count the 30 MHz clock signal 46, and when the count value matches the delay count value corresponding to 30 MHz, the counter output signals 48a to 48n are output. Each output signal is frequency-divided to 3.75 MHz by the second frequency divider 58, amplified by the amplifier 60, and each vibration element 12a to 12n has a corresponding transmission delay time of 3.75 MHz transmission drive. A signal is supplied.
[0034]
Similarly, when a transmission frequency other than this is selected, an instruction of the frequency division ratio is given to the first frequency divider 32 and the second frequency divider 58, and the reference delay count value and the selected frequency are displayed in the conversion table 74. An instruction for conversion to the delay count value corresponding to is given.
[0035]
In this way, if the reference delay count value corresponding to the reference frequency is calculated in advance for each vibration element, for each beam address, for each focus depth, etc. The corresponding delay count value need only be converted according to the frequency difference using the reference delay count value, and there is no need to hold the delay count values corresponding to all frequencies in the memory. Therefore, the memory capacity related to the transmission delay time can be reduced.
[0036]
Also, when the function of the ultrasonic apparatus is switched, only the corresponding delay count value is converted by the conversion table, so that the setting of the delay count value can be switched quickly.
[0037]
FIG. 2 is an example of the contents of the conversion table 74. The conversion table 74 includes a 40 MHz-30 MHz conversion table 90a used for conversion between the reference delay count value corresponding to the reference frequency 40 MHz and the delay count value corresponding to the selected frequency 30 MHz, and the reference delay corresponding to the reference frequency 40 MHz. It consists of a 40 MHz-24 MHz conversion table 90b used for conversion between the count value and the delay count value corresponding to the selected frequency 24 MHz. Both the 40 MHz-30 MHz conversion table 90a and the 40 MHz-24 MHz conversion table 90b have two left and right columns, the left column has a reference delay count value 92 and the right column has a delay count value 94a corresponding to the reference delay count value. , 94b.
[0038]
The left column shows all values from the minimum value to the maximum value that can be expressed by the number of bits representing the reference delay count value. For example, if the number of bits representing the reference delay count value is 10 bits, 2 10 power reference delay count values are sequentially arranged from the minimum value to the maximum value. In the figure, decimal notation is used for convenience of explanation, and rounding is used for conversion. For example, in the 40 MHz-30 MHz conversion table 90a, the reference delay count value is 20, and the corresponding delay count value is 15. The transmission delay time at this time is 20 * 25 nsec = 15 * 33.3 nsec = 500 nsec. The 40 MHz-24 MHz conversion table 90b has the same configuration. For example, the reference delay count value is 20, and the corresponding delay count value is 12.
[0039]
The content of the conversion table in FIG. 2 is an example, and the conversion table is not a set of conversion tables for each selected frequency, but in one table, for example, a 40 MHz reference delay count value is arranged in the leftmost column, and 2 from the left side. A delay count value corresponding to 30 MHz may be arranged in the first column, and a delay count value corresponding to 24 MHz may be arranged in the third column from the left side. In addition to the universal conversion format that can be converted for all reference delay count values, when the types of reference delay count values that are actually used are limited, only for the types of limited reference delay count values A limited conversion format may be used. Furthermore, in addition to using a table retrieval means for retrieving a reference delay count value in a table format such as a conversion table and outputting the corresponding delay count value, the selected frequency and the reference delay count value are input to correspond to the selected frequency. A memory that outputs a delay count value, for example, a semiconductor memory such as a ROM may be used.
[0040]
FIG. 3 is an example when the number of bits representing the reference delay count value is made larger than the number of bits representing the delay count value corresponding to the selected frequency in the conversion table. By doing so, the conversion becomes more accurate. In the figure, for convenience of explanation, the number of bits representing the delay count value corresponding to the selected frequency of 30 MHz is 4 bits, and the number of bits representing the reference delay count value corresponding to the reference frequency of 40 MHz is represented as the delay count value in (a). In 4 bits, which is the same as the number of bits, in (b), the lower bits are increased by 1 bit to give a total of 5 bits. In FIG. 3, the binary number is used to describe the number of bits. However, since the decimal notation is more convenient for explaining the principle, the count number in the decimal system is shown in parentheses. However, the decimal notation is used. However, the presence / absence of lower bits is indicated by the difference between (9 + 1 bits) and (9), for example.
[0041]
For example, when the reference delay count value is between 9 and 10, comparing the method using 4 bits and the method using 5 bits, the former rounds the reference delay count value to 10 by rounding off, for example, and converts it. Therefore, the corresponding delay count value is 8 as shown in FIG. On the other hand, in the latter method using 5 bits, the reference delay count value is converted as it is (9 + 1 bits) without being rounded, and converted according to the conversion table, so that the corresponding delay count value is 7 as shown in (b). A more accurate conversion result can be obtained. Similarly, when the reference delay count value is between 8 and 9, there is a difference between the method using 4 bits and the method using 5 bits, and the latter results in a more accurate conversion result.
[0042]
In the above description, the number of bits representing the reference delay count value is increased by one bit from the number of bits representing the delay count value corresponding to the selected frequency, but the number of bits can be further increased. Thus, the conversion can be performed more accurately by making the number of bits representing the reference delay count value larger than the number of bits representing the delay count corresponding to the selected frequency.
[0043]
【The invention's effect】
With the ultrasonic diagnostic apparatus according to the present invention, the capacity of a memory that stores transmission delay time can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram of a transmission unit of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing an example of the contents of a conversion table.
FIG. 3 is a diagram for explaining conversion when the number of bits representing a reference delay count value is increased.
FIG. 4 is a block diagram of a transmission unit of a conventional ultrasonic device.
[Explanation of symbols]
10, 70 Transmission unit of ultrasonic diagnostic apparatus, 11 ultrasonic transducer, 12a to 12n vibration element, 32 frequency divider (selection clock output means), 34a to 34n counter, 36 CPU (calculation means), 40a to 40n delay Count value setting unit, 46 clock signal, 48a to 48n counter output signal, 72 reference delay count value holding memory, 74 conversion table (conversion means), 92 reference delay count value, 94a, 94b corresponding delay count value.

Claims (4)

Counting a selected clock selected from a plurality of clocks with different frequencies, and outputting the selected clock when the count value matches the delay count value set to determine the transmission delay time, A control circuit for generating a transmission pulse of a transmission frequency based on the output;
A transmission circuit for generating a transmission drive pulse to be supplied to the ultrasonic transducer based on the transmission pulse;
In an ultrasonic diagnostic apparatus including a transmission unit having
A calculation means for replacing the transmission delay time with the count value of the clock of the reference frequency;
Means for converting a time indicated by a reference count value into a count value of the selected clock, and setting the converted count value as a delay count value for determining the transmission delay time;
An ultrasonic diagnostic apparatus comprising: A plurality of vibration elements for transmitting and receiving ultrasonic waves;
For each of the vibration elements, a selected clock selected from a plurality of clocks having different frequencies is counted, and each delay set to determine the count value and each transmission delay time corresponding to each vibration element A control circuit that outputs each of the selected clocks when the count value matches, and generates each transmission pulse of the transmission frequency based on each output;
A transmission circuit that generates each transmission drive pulse to be supplied to each vibration element based on each transmission pulse;
In an ultrasonic diagnostic apparatus including a transmission unit having
For each of the vibration elements, calculation means for replacing each transmission delay time with a clock count value of a reference frequency,
For each vibration element, the time indicated by the count value of the reference frequency clock is converted into the count value of the selected clock, and the converted count value is set as the delay count value for determining the transmission delay time. Means,
An ultrasonic diagnostic apparatus comprising: 3. The ultrasonic diagnostic apparatus according to claim 1, wherein the means for converting into the delay count value includes a clock count value of the reference frequency and a delay count value corresponding to each of the clocks of the plurality of different frequencies. And a conversion table between the selected clock frequency and the count value of the reference frequency clock, and a delay count value corresponding to the selected clock. Ultrasonic diagnostic equipment. 3. The ultrasonic diagnostic apparatus according to claim 1, wherein the number of bits representing the count value of the clock having the reference frequency is larger than the number of bits representing the delay count value corresponding to the selected clock. Ultrasonic diagnostic equipment.

Images