JP5692083B2 - Ultrasonic diagnostic equipment - Google Patents
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- JP5692083B2 JP5692083B2 JP2011537196A JP2011537196A JP5692083B2 JP 5692083 B2 JP5692083 B2 JP 5692083B2 JP 2011537196 A JP2011537196 A JP 2011537196A JP 2011537196 A JP2011537196 A JP 2011537196A JP 5692083 B2 JP5692083 B2 JP 5692083B2
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- 230000005540 biological transmission Effects 0.000 claims description 89
- 239000000523 sample Substances 0.000 claims description 34
- 238000002604 ultrasonography Methods 0.000 claims description 13
- 230000006835 compression Effects 0.000 claims description 10
- 238000007906 compression Methods 0.000 claims description 10
- 230000001934 delay Effects 0.000 claims description 5
- 238000003745 diagnosis Methods 0.000 claims 2
- 238000010586 diagram Methods 0.000 description 13
- 238000000034 method Methods 0.000 description 8
- 238000001514 detection method Methods 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 230000003111 delayed effect Effects 0.000 description 3
- 230000002238 attenuated effect Effects 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 210000001015 abdomen Anatomy 0.000 description 1
- 238000002059 diagnostic imaging Methods 0.000 description 1
- 238000002592 echocardiography Methods 0.000 description 1
- 210000003754 fetus Anatomy 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
- G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
- G01S15/8959—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using coded signals for correlation purposes
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
- G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
- G01S15/8959—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using coded signals for correlation purposes
- G01S15/8963—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques using coded signals for correlation purposes using pulse inversion
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S15/00—Systems using the reflection or reradiation of acoustic waves, e.g. sonar systems
- G01S15/88—Sonar systems specially adapted for specific applications
- G01S15/89—Sonar systems specially adapted for specific applications for mapping or imaging
- G01S15/8906—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques
- G01S15/895—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques characterised by the transmitted frequency spectrum
- G01S15/8954—Short-range imaging systems; Acoustic microscope systems using pulse-echo techniques characterised by the transmitted frequency spectrum using a broad-band spectrum
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/52—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00
- G01S7/52017—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S15/00 particularly adapted to short-range imaging
- G01S7/52023—Details of receivers
- G01S7/52036—Details of receivers using analysis of echo signal for target characterisation
- G01S7/52038—Details of receivers using analysis of echo signal for target characterisation involving non-linear properties of the propagation medium or of the reflective target
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- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Acoustics & Sound (AREA)
- Computer Networks & Wireless Communication (AREA)
- General Physics & Mathematics (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
Description
本発明は、超音波診断装置に関する。 The present invention relates to an ultrasonic diagnostic apparatus.
超音波診断装置は、被検体の画像をほぼリアルタイムでモニタに表示して観察でき、また、放射線を用いる画像診断装置のような放射線被爆を被検体に与えないことから安全性も高く、広く医療の分野で用いられている。 Ultrasound diagnostic devices can display images of a subject on a monitor in real time and observe them. Also, they do not give radiation exposure to subjects like radiation-based diagnostic imaging devices. It is used in the field.
超音波撮像装置の超音波探触子から生体に対して送波する超音波の波形は、その波形の長さが距離分解能を決めるので、できるだけ時間軸方向に短いパルス波を用いる方が良い。 Since the waveform length of the ultrasonic wave transmitted from the ultrasonic probe of the ultrasonic imaging apparatus to the living body determines the distance resolution, it is better to use a pulse wave that is as short as possible in the time axis direction.
一方で、ノイズに対する信号の強度比であるS/N比を良くするには信号強度が大きい方が良いが、生体に与える影響を考慮して信号強度を一定値以下に制限する必要がある。そのため、パルスの発生する時間や周波数を分散させた分散圧縮送受信が用いられている。 On the other hand, in order to improve the S / N ratio, which is the signal intensity ratio with respect to noise, it is better that the signal intensity is high. Therefore, distributed compression transmission / reception in which the time and frequency at which pulses are generated is distributed is used.
例えば、特許文献1には、時間軸方向に伸ばした符号化信号を送波し、被検体内で反射した信号を受波し、電気信号に変換した後に復号して時間軸方向に圧縮し、ピーク値の大きいパルス波形に戻す符号化送受信法による分散圧縮送受信が記載されている。 For example, in Patent Document 1, a coded signal extended in the time axis direction is transmitted, a signal reflected in the subject is received, converted into an electric signal, decoded, and compressed in the time axis direction, A description is given of distributed compression transmission / reception by an encoded transmission / reception method for returning to a pulse waveform having a large peak value.
特許文献2には、リニアチャープ信号を送波し、被検体内で反射した信号を受波し、電気信号に変換した後に、受信した信号波形と送波信号との相互相関を求めることにより復調するスペクトラム拡散方式による分散圧縮送受信が記載されている。 In Patent Document 2, a linear chirp signal is transmitted, a signal reflected in a subject is received, converted into an electrical signal, and then demodulated by obtaining a cross-correlation between the received signal waveform and the transmitted signal. The spread compression transmission / reception by the spread spectrum method is described.
また、従来より超音波診断装置では、超音波の非線形な伝播により生じる高調波成分を取りだし、この高調波成分に基づいて超音波画像を生成し、表示するハーモニックイメージング(HI)法と呼ばれている手法が用いられてきた(例えば、特許文献3参照)。高調波成分を利用すると、S/Nの向上や横方向分解能の向上、多重反射の抑制等の様々な利点がある。 Conventionally, in an ultrasonic diagnostic apparatus, it is called a harmonic imaging (HI) method in which a harmonic component generated by nonlinear propagation of an ultrasonic wave is taken out and an ultrasonic image is generated and displayed based on the harmonic component. Have been used (see, for example, Patent Document 3). The use of the harmonic component has various advantages such as improvement of S / N, improvement of lateral resolution, and suppression of multiple reflection.
高次の高調波を抽出する技術としては、パルスインバージョンによる方法が知られている。例えば、特許文献4では、互いに位相が反転関係にある超音波の組を送波し、この超音波の組のうち一方に対応する受信信号と、他方に対応する受信信号の差分を算出して3次の高調波成分を抽出する方法が開示されている。 As a technique for extracting higher-order harmonics, a method based on pulse inversion is known. For example, in Patent Document 4, a set of ultrasonic waves whose phases are inverted with respect to each other is transmitted, and a difference between a received signal corresponding to one of the ultrasonic sets and a received signal corresponding to the other is calculated. A method for extracting third-order harmonic components is disclosed.
分散圧縮送受信を用いる場合も、高調波成分を抽出することができればより一層の画質の向上が期待できる。 Even in the case of using distributed compression transmission / reception, further improvement in image quality can be expected if harmonic components can be extracted.
しかしながら、分散圧縮送受信を用いる場合は送信信号の周波数帯域の広さから基本波と高調波との互いの周波数帯域が重なるため、パルスインバージョンを適用しても対象とするn次高調波のみを抽出することが困難であった。 However, when using distributed compression transmission / reception, the frequency bands of the transmission signal overlap each other because the frequency bands of the fundamental wave and the harmonics overlap each other, so that only the target n-order harmonics are applied even if pulse inversion is applied. It was difficult to extract.
本発明は、上記課題に鑑みてなされたものであって、分散圧縮による送受信を用いて対象とするn次高調波を抽出することができる超音波診断装置を提供することを目的とする。 The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of extracting a target n-order harmonic using transmission and reception by distributed compression.
上記の課題を解決するため、本発明は以下のような特徴を有するものである。 In order to solve the above problems, the present invention has the following characteristics.
1.被検体に超音波を送波する超音波探触子と、所望の基本周波数の成分を有する分散圧縮した第1の送信信号と前記第1の送信信号を反転した第2の送信信号とを順に生成して超音波探触子を駆動する送信処理部と、前記超音波探触子が受信した前記第1の送信信号に対応する第1の受信信号と前記第2の送信信号に対応する第2の受信信号との差分信号または和信号の少なくとも一方を伸張して出力する受信処理部と、前記受信処理部の出力する伸張された信号を用いて超音波画像を生成する画像生成部と、前記画像生成部で生成された超音波画像を表示する表示部と、を備えた超音波診断装置であって、
前記超音波探触子から送波される超音波の基本周波数をf0、周波数帯域の上限の周波数をf2とすると、f2<2f0になるように構成されており、
前記超音波探触子から送波される超音波の音圧の利得は、基本周波数f 0 より周波数が高くなるにつれて増加し、基本周波数f 0 より周波数が低くなるにつれて減少する周波数範囲を有することを特徴とする超音波診断装置。
1. An ultrasonic probe that transmits ultrasonic waves to the subject, a first transmission signal that is distributed and compressed having a component of a desired fundamental frequency, and a second transmission signal that is an inversion of the first transmission signal, in this order. A transmission processing unit that generates and drives the ultrasound probe; a first reception signal that corresponds to the first transmission signal that is received by the ultrasound probe; and a second signal that corresponds to the second transmission signal. A reception processing unit that expands and outputs at least one of a difference signal or a sum signal from the received signal of 2; an image generation unit that generates an ultrasonic image using the expanded signal output from the reception processing unit; A display unit for displaying an ultrasonic image generated by the image generation unit, and an ultrasonic diagnostic apparatus comprising:
When the fundamental frequency of the ultrasonic wave transmitted from the ultrasonic probe is f 0 and the upper limit frequency of the frequency band is f 2 , f 2 <2f 0 is satisfied .
Gain of ultrasonic sound pressure that is transmitting from the ultrasound probe increases as the frequency than the fundamental frequency f 0 is higher, have a reduced frequency range as the frequency than the fundamental frequency f 0 is lowered An ultrasonic diagnostic apparatus characterized by the above.
2.周波数帯域の下限の周波数をf1とすると(f0−f1)>(f2−f0)であることを特徴とする前記1に記載の超音波診断装置。2. 2. The ultrasonic diagnostic apparatus according to 1 above, wherein (f 0 −f 1 )> (f 2 −f 0 ), where f 1 is a lower limit frequency of the frequency band.
3.前記受信処理部は、
前記第1の受信信号の送信を開始した時間と前記第2の受信信号の送信を開始した時間の時間差に相当する間、前記第1の受信信号を遅延させる遅延部と、
前記遅延部の出力と、前記第2の受信信号との差分を前記差分信号として算出する減算器と、
を有することを特徴とする前記1または2に記載の超音波診断装置。
3 . The reception processing unit
A delay unit that delays the first reception signal for a time difference between a time at which transmission of the first reception signal is started and a time at which transmission of the second reception signal is started;
A subtractor that calculates a difference between the output of the delay unit and the second received signal as the difference signal;
The ultrasonic diagnostic apparatus according to 1 or 2 above, characterized by comprising:
4.前記受信処理部は、
前記第1の受信信号の送信を開始した時間と前記第2の受信信号の送信を開始した時間の時間差に相当する間、前記第1の受信信号を遅延させる遅延部と、
前記遅延部の出力と、前記第2の受信信号との和を前記和信号として算出する加算器と、
を有することを特徴とする前記1から3の何れか1項に記載の超音波診断装置。
4 . The reception processing unit
A delay unit that delays the first reception signal for a time difference between a time at which transmission of the first reception signal is started and a time at which transmission of the second reception signal is started;
An adder that calculates the sum of the output of the delay unit and the second received signal as the sum signal;
The ultrasonic diagnostic apparatus according to any one of 1 to 3 , characterized by comprising:
5.前記受信処理部は、
前記差分信号または前記和信号について変調符号列による分散圧縮を伸張する復調フィルタと、
前記復調フィルタによって伸張された信号の包絡線を検波して出力する包絡線検波部と、
を有することを特徴とする前記3または4に記載の超音波診断装置。
5 . The reception processing unit
A demodulation filter for expanding distributed compression by a modulation code string for the differential signal or the sum signal;
An envelope detector for detecting and outputting an envelope of the signal expanded by the demodulation filter;
The ultrasonic diagnostic apparatus according to 3 or 4 above, characterized by comprising:
6.前記送信処理部は、
互いに符号が反転関係にある1組のBarker符号を前記第1の送信信号および前記第2の送信信号として生成することを特徴とする前記3から5の何れか1項に記載の超音波診断装置。
6 . The transmission processing unit
6. The ultrasonic diagnostic apparatus according to any one of 3 to 5 , wherein a pair of Barker codes whose signs are inverted with respect to each other are generated as the first transmission signal and the second transmission signal. .
7.前記送信処理部は、
前記第1の送信信号および前記第2の送信信号にPSK変調を行って出力することを特徴とする前記6に記載の超音波診断装置。
7 . The transmission processing unit
7. The ultrasonic diagnostic apparatus according to 6 , wherein the first transmission signal and the second transmission signal are subjected to PSK modulation and output.
8.前記送信処理部は、
互いに位相が反転関係にある1組のチャープ信号を前記第1の送信信号および前記第2の送信信号として生成することを特徴とする前記3から5の何れか1項に記載の超音波診断装置。
8 . The transmission processing unit
6. The ultrasonic diagnostic apparatus according to any one of 3 to 5 , wherein a pair of chirp signals whose phases are inverted are generated as the first transmission signal and the second transmission signal. .
本発明によれば、超音波探触子から送波される超音波の基本周波数をf0、周波数帯域の上限の周波数をf2とすると、f2<2f0になるように構成されている。このようにすると、受信信号の基本波の帯域と3次高調波の帯域が重ならないのでパルスインバージョンを適用して所定の次数の高調波を抽出することができる。According to the present invention, when the basic frequency of the ultrasonic wave transmitted from the ultrasonic probe is f 0 and the upper limit frequency of the frequency band is f 2 , f 2 <2f 0 is satisfied. . In this way, since the fundamental wave band of the received signal and the third harmonic band do not overlap, it is possible to extract a harmonic of a predetermined order by applying pulse inversion.
したがって、分散圧縮による送受信を用いて対象とするn次高調波を抽出することができる。 Therefore, it is possible to extract a target n-order harmonic using transmission / reception by distributed compression.
以下、本発明に係る実施の一形態を図面に基づいて説明するが、本発明は該実施の形態に限られない。なお、各図において同一の符号を付した構成は、同一の構成であることを示し、その説明を省略する。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiment. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted.
図1は、実施形態に係る超音波診断装置の電気的な構成を示すブロック図、図2は、実施形態の送信処理部1の一例の回路ブロック図、図3は、符号化の次数が5のBarker符号を説明する図である。 FIG. 1 is a block diagram showing an electrical configuration of the ultrasonic diagnostic apparatus according to the embodiment, FIG. 2 is a circuit block diagram of an example of the transmission processing unit 1 of the embodiment, and FIG. It is a figure explaining the Barker code | symbol of.
最初に図1、図2、図3を用いて超音波診断装置の構成の一例を説明する。 First, an example of the configuration of the ultrasonic diagnostic apparatus will be described with reference to FIGS. 1, 2, and 3.
超音波画像観察装置100は、超音波探触子2から図略の被検体である例えば妊婦の腹部に対して超音波(超音波信号)を送信し、被検体の内部から反射した超音波の反射波(エコー、超音波信号)から被検体内の胎児の状態を超音波画像として画像化し、表示部10に表示する。 The ultrasonic image observation apparatus 100 transmits an ultrasonic wave (ultrasonic signal) from the ultrasonic probe 2 to a not-illustrated subject, for example, the abdomen of a pregnant woman, and reflects the ultrasonic wave reflected from the inside of the subject. The state of the fetus in the subject is imaged as an ultrasound image from the reflected wave (echo, ultrasound signal) and displayed on the display unit 10.
入力部13は、超音波画像観察装置100の電源を投入する電源スイッチや、例えばキーボード、タッチパネルなどの入力手段から構成されている。 The input unit 13 includes a power switch for turning on the ultrasonic image observation apparatus 100 and input means such as a keyboard and a touch panel.
制御部99は、CPU98(中央処理装置)と記憶部96等から構成され、記憶部96に記憶されているプログラムをRAM(Random Access Memory)に読み出し、当該プログラムに従って超音波画像観察装置100の各部を制御する。記憶部96は、RAM(Random Access Memory)、ROM(Read Only Memory)、ハードディスク等から構成される。 The control unit 99 includes a CPU 98 (central processing unit), a storage unit 96, and the like, reads a program stored in the storage unit 96 into a RAM (Random Access Memory), and each unit of the ultrasonic image observation apparatus 100 according to the program. To control. The storage unit 96 includes a RAM (Random Access Memory), a ROM (Read Only Memory), a hard disk, and the like.
超音波探触子2は、図示せぬ被検体に対して超音波を送波し、被検体で反射した超音波の反射波を受信する。超音波探触子2は、図1に示すように、送信処理部1、受信処理部3と電気的に接続されている。 The ultrasonic probe 2 transmits an ultrasonic wave to a subject (not shown) and receives a reflected wave of the ultrasonic wave reflected by the subject. As shown in FIG. 1, the ultrasound probe 2 is electrically connected to a transmission processing unit 1 and a reception processing unit 3.
超音波探触子2は、送信処理部1から送信された送信信号によって超音波を送波する。 The ultrasonic probe 2 transmits ultrasonic waves using the transmission signal transmitted from the transmission processing unit 1.
図2、図3を用いて、実施形態の送信処理部1の一例を説明する。 An example of the transmission processing unit 1 according to the embodiment will be described with reference to FIGS.
送信処理部1は、タイミング信号発生部25、符号選択部26、符号記憶部23、PSK変調部22、FLT29、送波アンプ21を備える。 The transmission processing unit 1 includes a timing signal generation unit 25, a code selection unit 26, a code storage unit 23, a PSK modulation unit 22, an FLT 29, and a transmission amplifier 21.
タイミング信号発生部25は、制御部99の指令により送信処理部1の各部にタイミングクロックを供給する。 The timing signal generation unit 25 supplies a timing clock to each unit of the transmission processing unit 1 according to a command from the control unit 99.
符号選択部26は、制御部99の指令により符号記憶部23に格納されている符号化の次数が複数種類の変調符号のうち何れか一つを選択する。医師など操作者は、入力部13から操作することにより符号選択部26が選択する変調符号の種類を設定することができる。 The code selection unit 26 selects any one of a plurality of types of modulation codes with the order of encoding stored in the code storage unit 23 according to a command from the control unit 99. An operator such as a doctor can set the type of modulation code selected by the code selection unit 26 by operating from the input unit 13.
符号記憶部23には、互いに符号が反転関係にある少なくとも1組の変調符号が予め格納されている。変調符号は、公知のBarker符号であり、所定の符号化の次数のBarker符号の組み合わせである変調符号が予め符号記憶部23に格納されている。 The code storage unit 23 stores in advance at least one set of modulation codes whose codes are in an inverted relationship. The modulation code is a known Barker code, and a modulation code that is a combination of Barker codes of a predetermined encoding order is stored in the code storage unit 23 in advance.
図3は、符号記憶部23に格納されている互いに符号が反転関係にある1組のBarker符号の例である。図3は符号化の次数が5次のBarker符号の例であり、(+1、+1、+1、−1、+1)の部分が第1の送信信号、これに続く(−1、−1、−1、+1、−1)の部分が第1の送信信号を反転した第2の送信信号である。このように符号記憶部23から第1の送信信号と第2の送信信号が順に出力される。 FIG. 3 is an example of a set of Barker codes stored in the code storage unit 23 and whose codes are in an inverted relationship with each other. FIG. 3 shows an example of a Barker code having a 5th-order encoding. The (+1, +1, +1, −1, +1) portion is the first transmission signal, followed by (−1, −1, − 1, +1, −1) is a second transmission signal obtained by inverting the first transmission signal. As described above, the first transmission signal and the second transmission signal are sequentially output from the code storage unit 23.
符号選択部26は、この変調符号が格納されている符号記憶部23のアドレスを指定し、所定の時間間隔Tで出力するよう制御する。 The code selection unit 26 designates the address of the code storage unit 23 in which the modulation code is stored, and controls to output at a predetermined time interval T.
PSK(Phase Shift Keying)変調部22は、符号記憶部23から出力された符号要素の係数+1または−1に応じて、一定周波数の搬送波の位相を変化させて変調する。すなわち、基本波形(位相0°)と、基本波形に対して180°位相をずらした波形を出力する。PSK変調を行うことにより狭い周波数帯域で多くの情報を伝送することができ、ノイズや信号の減衰に影響されにくくすることができる。 A PSK (Phase Shift Keying) modulation unit 22 performs modulation by changing the phase of a carrier wave having a constant frequency in accordance with the coefficient +1 or −1 of the code element output from the code storage unit 23. That is, a basic waveform (phase 0 °) and a waveform whose phase is shifted by 180 ° from the basic waveform are output. By performing PSK modulation, a large amount of information can be transmitted in a narrow frequency band and can be made less susceptible to noise and signal attenuation.
FLT29は、送信信号の帯域を制限するバンドパスフィルタなどのフィルタである。FLT29の特性については後に詳しく説明する。 The FLT 29 is a filter such as a bandpass filter that limits the band of the transmission signal. The characteristics of the FLT 29 will be described in detail later.
送波アンプ21は、FLT29で帯域制限された第1の送信信号、第2の送信信号を増幅し、所望の基本周波数f0の成分を有する駆動信号で超音波探触子2を駆動する。Transmitting amplifier 21, a first transmission signal band-limited by FLT29, amplifies the second transmission signal, drives the ultrasonic probe 2 in the drive signal having a component of the desired fundamental frequency f 0.
次に、受信時の信号処理について図1を用いて説明する。 Next, signal processing during reception will be described with reference to FIG.
超音波探触子2から超音波を被検体に向けて送波した後、超音波探触子2に返ってきたエコーは、超音波探触子2に配列された図示せぬ圧電素子を機械的に振動させ、微弱な受信信号を発生させる。以下の説明では、第1の送信信号によって送波した超音波に対応する受信信号を第1の受信信号、第2の送信信号によって送波した超音波に対応する受信信号を第2の受信信号と呼ぶ。 After transmitting ultrasonic waves from the ultrasonic probe 2 toward the subject, the echoes returned to the ultrasonic probe 2 are mechanically operated by piezoelectric elements (not shown) arranged in the ultrasonic probe 2. To generate a weak received signal. In the following description, the reception signal corresponding to the ultrasonic wave transmitted by the first transmission signal is the first reception signal, and the reception signal corresponding to the ultrasonic wave transmitted by the second transmission signal is the second reception signal. Call it.
受信処理部3は、第1の受信信号、第2の受信信号を順に受信して所定の信号レベルに増幅した後、第1の受信信号と第2の受信信号にパルスインバージョンを行って基本波、または高調波の分散圧縮された成分を抽出し、伸張した後、包絡線検波を行った信号を出力する。受信処理部3で行う信号処理は、後に詳しく説明する。 The reception processing unit 3 receives the first reception signal and the second reception signal in order and amplifies them to a predetermined signal level, and then performs pulse inversion on the first reception signal and the second reception signal to perform basic processing. After extracting and expanding the component of the wave or harmonic that has been distributed and compressed, a signal subjected to envelope detection is output. The signal processing performed by the reception processing unit 3 will be described in detail later.
画像生成部6は、受信処理部3から出力された信号に基づいてBモード画像を生成する。 The image generation unit 6 generates a B-mode image based on the signal output from the reception processing unit 3.
画像処理部で画像処理された画像は、デジタルスキャンコンバータ(DSC)9によってビデオ信号に変換され、表示部10に表示される。 The image processed by the image processing unit is converted into a video signal by a digital scan converter (DSC) 9 and displayed on the display unit 10.
なお、図3では送信処理部1の出力する変調符号の一例として符号化の次数が5のBarker符号を説明したが、特にこの次数に限られるものではない。検出対象のコントラストに応じて最適な画像が得られる次数を設定すれば良い。 In FIG. 3, the Barker code having the encoding order of 5 is described as an example of the modulation code output from the transmission processing unit 1, but the order is not particularly limited to this order. What is necessary is just to set the order from which an optimal image is obtained according to the contrast of a detection target.
次に、実施形態の送信処理部1の他の例について説明する。 Next, another example of the transmission processing unit 1 according to the embodiment will be described.
図4は、実施形態の送信処理部1の他の例の詳細な回路ブロック図、図5は、本実施形態で生成するチャープ信号を説明する図である。 FIG. 4 is a detailed circuit block diagram of another example of the transmission processing unit 1 according to the embodiment, and FIG. 5 is a diagram illustrating a chirp signal generated in the present embodiment.
コード生成部27は、チャープ信号を生成する符号を予め記憶し、制御部99からの指令により所定のクロックに従って記憶している符号を出力する。 The code generation unit 27 stores a code for generating a chirp signal in advance, and outputs the stored code in accordance with a predetermined clock according to a command from the control unit 99.
D/A変換器26は、コード生成部27の順次出力する符号をアナログ信号に変換し出力する。図5は、生成されたチャープ信号を説明する図である。図中T1の期間が第1の送信信号であり、T2の期間が第1の送信信号を反転した第2の送信信号である。第1の送信信号と第2の送信信号は、時間とともに周波数が高くなるチャープ信号である。The D / A converter 26 converts the code sequentially output from the code generation unit 27 into an analog signal and outputs the analog signal. FIG. 5 is a diagram for explaining the generated chirp signal. In the figure, a period T1 is a first transmission signal, and a period T2 is a second transmission signal obtained by inverting the first transmission signal. The first transmission signal and the second transmission signal are chirp signals whose frequency increases with time.
FLT29は、送信信号の帯域を制限するバンドパスフィルタなどのフィルタである。FLT29の特性については後に詳しく説明する。 The FLT 29 is a filter such as a bandpass filter that limits the band of the transmission signal. The characteristics of the FLT 29 will be described in detail later.
送波アンプ21は、フィルタで帯域制限された第1の送信信号、第2の送信信号を増幅し、所望の基本周波数f0の成分を有する駆動信号で超音波探触子2を駆動する。Transmitting amplifier 21, a first transmission signal band-limited by filter, amplifies the second transmission signal, drives the ultrasonic probe 2 in the drive signal having a component of the desired fundamental frequency f 0.
次に、本実施形態の受信処理について図6、図7を用いて説明する。 Next, the reception process of this embodiment is demonstrated using FIG. 6, FIG.
図6は、第1の実施形態の受信処理部の電気的な構成を示すブロック図、図7は、第2の実施形態の受信処理部の電気的な構成を示すブロック図である。 FIG. 6 is a block diagram illustrating an electrical configuration of the reception processing unit according to the first embodiment, and FIG. 7 is a block diagram illustrating an electrical configuration of the reception processing unit according to the second embodiment.
最初に図6の受信処理部3を説明する。 First, the reception processing unit 3 in FIG. 6 will be described.
受信回路31は、超音波探触子2が出力する第1の受信信号と第2の受信信号を順に受信して所定の信号レベルに増幅する。増幅された信号は、A/D変換器32によりデジタル値に変換される。 The reception circuit 31 sequentially receives the first reception signal and the second reception signal output from the ultrasound probe 2 and amplifies them to a predetermined signal level. The amplified signal is converted into a digital value by the A / D converter 32.
遅延部33は、例えばラインメモリであり、第1の受信信号を第1の受信信号の送信を開始した時間と前記第2の受信信号の送信を開始した時間の時間差に相当する間遅延させる。A/D変換器32の出力は遅延部33に入力され、第1の受信信号を該時間差に相当する間遅延して減算器34に入力する。 The delay unit 33 is a line memory, for example, and delays the first reception signal for a time corresponding to the time difference between the time when transmission of the first reception signal is started and the time when transmission of the second reception signal is started. The output of the A / D converter 32 is input to the delay unit 33, and the first received signal is delayed for a time corresponding to the time difference and input to the subtractor 34.
減算器34は、遅延部33の入力信号と遅延部33の出力信号とを減算する。前述のように遅延部33で第1の受信信号は遅延されるので、減算器34には第1の受信信号と第2の受信信号とが同時に入力され、第1の受信信号と第2の受信信号の差分が減算器34から差分信号として出力される。 The subtracter 34 subtracts the input signal of the delay unit 33 and the output signal of the delay unit 33. Since the first reception signal is delayed by the delay unit 33 as described above, the first reception signal and the second reception signal are simultaneously input to the subtractor 34, and the first reception signal and the second reception signal are input. The difference between the received signals is output from the subtracter 34 as a difference signal.
差分信号には、第1の受信信号と第2の受信信号で同位相の2次高調波2f0の成分が減算することにより除去され、第1の受信信号と第2の受信信号とで逆位相の基本周波数f0の成分と3次高調波3f0の成分が残っている。The difference signal is removed by subtracting the component of the second harmonic 2f 0 having the same phase between the first received signal and the second received signal, and the first received signal and the second received signal are reversed. remaining ingredients and components of the third harmonic 3f 0 of the fundamental frequency f 0 of the phase.
差分信号は、基本波LPF(ローパスフィルタ)36と3次高調波BPF(バンドパスフィルタ)35とに入力され、基本周波数f0の成分と3次高調波3f0の成分に分離される。Differential signal is inputted to the fundamental wave LPF (low pass filter) 36 and the third harmonic BPF (band pass filter) 35 is separated into components of the component of the fundamental frequency f 0 and the third-order harmonic 3f 0.
基本波LPF36は、主に減算器34の出力に含まれる超音波探触子2の送波する超音波の基本周波数f0とその側帯波の帯域を通過させる。3次高調波BPF35は、主に減算器34の出力に含まれる超音波探触子2の送波する超音波の3次高調波3f0とその側帯波の帯域を通過させる。The fundamental wave LPF 36 mainly passes the fundamental frequency f 0 of the ultrasonic wave transmitted by the ultrasonic probe 2 included in the output of the subtractor 34 and the sideband band thereof. The third harmonic BPF 35 mainly passes the band of the third harmonic 3f 0 of the ultrasonic wave transmitted by the ultrasonic probe 2 included in the output of the subtractor 34 and its sideband.
SW(スイッチ)37は、制御部99の指令により基本波LPF36、または3次高調波BPF35の出力を切り替えて不整合フィルタ(復調フィルタ)39に出力する。 The SW (switch) 37 switches the output of the fundamental wave LPF 36 or the third harmonic BPF 35 according to a command from the control unit 99 and outputs the switched signal to the mismatch filter (demodulation filter) 39.
不整合フィルタ39は、FIRフィルタ等により構成され、送信処理部1の生成した変調信号に対応する係数を予め保持し、受信した分散圧縮されている信号を伸張する。 The mismatch filter 39 is configured by an FIR filter or the like, holds in advance a coefficient corresponding to the modulated signal generated by the transmission processing unit 1, and expands the received dispersion-compressed signal.
例えば、送信処理部1の生成した変調符号がBarker符号の場合であれば、超音波送信時に制御部99から、Barker符号の係数を時間軸について反転させた不整合フィルタ係数が不整合フィルタ39に設定される。不整合フィルタ係数は、ピーク値をできるだけ保ちながらサイドローブを最小化するように決定された係数の大きさが1ではない係数である。不整合フィルタ39は、受信した信号の値と不整合フィルタ係数との積和演算を行って伸張する。 For example, if the modulation code generated by the transmission processing unit 1 is a Barker code, the mismatch filter coefficient obtained by inverting the coefficient of the Barker code with respect to the time axis is supplied to the mismatch filter 39 from the control unit 99 during ultrasonic transmission. Is set. The mismatch filter coefficient is a coefficient whose coefficient magnitude is determined not to be 1 so as to minimize the side lobe while keeping the peak value as much as possible. The mismatch filter 39 performs a product-sum operation on the received signal value and the mismatch filter coefficient, and expands the result.
包絡線検波部40は、不整合フィルタ39の出力を検波し、検波出力を画像生成部6に出力する。 The envelope detection unit 40 detects the output of the mismatch filter 39 and outputs the detection output to the image generation unit 6.
図6の受信処理部3の説明は以上である。 The description of the reception processing unit 3 in FIG.
次に図7の受信処理部3を説明する。 Next, the reception processing unit 3 in FIG. 7 will be described.
図7の受信処理部3は、遅延部33の入力信号と遅延部33の出力信号とを加算器41を有する点が図6の受信処理部3と異なる。その他の構成要素は図6と同じであり、同じ機能の構成要素には同番号を付し、説明を省略する。 The reception processing unit 3 in FIG. 7 is different from the reception processing unit 3 in FIG. 6 in that an adder 41 is provided between the input signal of the delay unit 33 and the output signal of the delay unit 33. The other constituent elements are the same as those in FIG. 6, and the constituent elements having the same functions are denoted by the same reference numerals and the description thereof is omitted.
前述のように遅延部33で第1の受信信号は遅延されるので、遅延部33には第1の受信信号と第2の受信信号とが同時に入力され、第1の受信信号と第2の受信信号が加算された和信号が出力される。 As described above, since the first reception signal is delayed by the delay unit 33, the first reception signal and the second reception signal are simultaneously input to the delay unit 33, and the first reception signal and the second reception signal are input. A sum signal obtained by adding the received signals is output.
和信号には、第1の受信信号と第2の受信信号で逆位相の基本周波数f0の成分と3次高調波3f0の成分が加算することにより除去され、第1の受信信号と第2の受信信号とで同位相の2次高調波2f0の成分が残っている。The sum signal is removed by the components of the first received signal and the component and the third harmonic 3f 0 of the fundamental frequency f 0 of the opposite phase with the second reception signal is added, the first received signal and the The second harmonic 2f 0 component remains in phase with the received signal 2.
和信号は、2次高調波BPF(バンドパスフィルタ)42に入力され、2次高調波2f0の成分が分離される。The sum signal is input to the second harmonic wave BPF (band pass filter) 42, the component of the second harmonic 2f 0 is separated.
SW37は、制御部99の指令により基本波LPF36、2次高調波BPF42、または3次高調波BPF35の出力を切り替えて不整合フィルタ39に出力する。 The SW 37 switches the output of the fundamental wave LPF 36, the second harmonic BPF 42, or the third harmonic BPF 35 according to a command from the control unit 99 and outputs the switched output to the mismatch filter 39.
なお、この例に限らず、基本波LPF36、2次高調波BPF42、または3次高調波BPF35の何れか一つを備え、SW37による切り替えを行わない構成や、2次高調波BPF42と3次高調波BPF35の2つを切り替える構成などでも良い。 Not limited to this example, any one of the fundamental wave LPF 36, the second harmonic BPF 42, or the third harmonic BPF 35 is provided, and the switching by the SW 37 is not performed, and the second harmonic BPF 42 and the third harmonic are not switched. A configuration in which two of the waves BPF 35 are switched may be used.
このように、本実施形態では互いに位相が反転関係にある超音波の組を送波し、この超音波の組のうち一方に対応する受信信号と、他方に対応する受信信号の差分信号または和信号を算出してn次の高調波成分を抽出することができる。 As described above, in this embodiment, a pair of ultrasonic waves whose phases are inverted with respect to each other is transmitted, and a difference signal or a sum of a reception signal corresponding to one of the ultrasonic waves and a reception signal corresponding to the other is transmitted. The signal can be calculated to extract the nth-order harmonic component.
次に、これまで実施形態で説明したパルスインバージョンの信号処理を行う際に、所定の次数の高調波を抽出するため基本波と3次高調波のスペクトラムを重ならないようにする条件を説明する。 Next, when performing the signal processing of the pulse inversion described in the embodiments so far, conditions for preventing the fundamental and third harmonics from overlapping the spectrum in order to extract the harmonics of a predetermined order will be described. .
図8は、超音波探触子2から送波される超音波の周波数特性の一例を示すグラフ、図9は、加算または減算後の受信信号の周波数スペクトラムを説明する図である。 FIG. 8 is a graph showing an example of the frequency characteristic of the ultrasonic wave transmitted from the ultrasonic probe 2, and FIG. 9 is a diagram for explaining the frequency spectrum of the received signal after addition or subtraction.
図中、f0は超音波探触子2から送波される超音波の基本周波数、G0は基本周波数f0における超音波の音圧の利得である。図8のように利得G0から3dB利得が低下する周波数はf1とf2である。したがって、f1は周波数帯域の下限の周波数、f2は周波数帯域の上限の周波数である。In the figure, f 0 is the fundamental frequency of the ultrasonic wave transmitting from the ultrasound probe 2, G 0 is the gain of the ultrasonic sound pressure at the fundamental frequency f 0. As shown in FIG. 8, the frequencies at which the 3 dB gain decreases from the gain G 0 are f 1 and f 2 . Therefore, f 1 is the lower limit frequency of the frequency band, and f 2 is the upper limit frequency of the frequency band.
また、図8に示すようにf2<2f0であり、2次高調波の周波数であるf0の2倍の2f0より高い周波数成分は十分減衰されている。Further, as shown in FIG. 8, f 2 <2f 0 , and the frequency component higher than 2f 0 which is twice the frequency of f 0 which is the frequency of the second harmonic is sufficiently attenuated.
例えば、f0が3MHzの場合、f1を1MHz、f2を5MHzにすると良い。2f0は6MHzであり、f2<2f0の条件を満たすので、2次高調波である6MHzと3次高調波とを抽出することが可能になる。For example, when f 0 is 3 MHz, f 1 may be 1 MHz and f 2 may be 5 MHz. Since 2f 0 is 6 MHz and satisfies the condition of f 2 <2f 0 , it is possible to extract 6 MHz and the third harmonic, which are second harmonics.
このような超音波探触子2から送波される超音波の周波数特性は、例えば送信処理部のFLT29を図8のような周波数特性のバンドパスフィルタにして帯域制限することで実現できる。 Such a frequency characteristic of the ultrasonic wave transmitted from the ultrasonic probe 2 can be realized, for example, by limiting the band by using the FLT 29 of the transmission processing unit as a bandpass filter having a frequency characteristic as shown in FIG.
なお、超音波探触子2の圧電素子や送波アンプ21の周波数帯域が十分広い場合は、主にFLT29により周波数帯域が決定されるが、これらの周波数帯域が狭い場合は、圧電素子の周波数特性や送波アンプ21の特性など総合特性を考慮して設定することが望ましい。 If the frequency band of the piezoelectric element of the ultrasonic probe 2 or the transmission amplifier 21 is sufficiently wide, the frequency band is mainly determined by the FLT 29. If these frequency bands are narrow, the frequency of the piezoelectric element is determined. It is desirable to set in consideration of the overall characteristics such as the characteristics and the characteristics of the transmission amplifier 21.
図9(a)は、図8に示す周波数特性の超音波を送波した場合の受信信号を減算器34で減算した出力例であり、図9(b)は加算器41の出力例である。図9(a)では、減算後の差分信号に残った基本周波数の成分51と3次高調波の成分53が実線で示され、除去された2次高調波の成分52が点線で表示されている。図9(b)は、加算後の和信号に残った2次高調波の成分52が実線で示され、除去された基本周波数の成分51と3次高調波の成分53が点線で表示されている。 FIG. 9A shows an output example obtained by subtracting the reception signal when the ultrasonic wave having the frequency characteristic shown in FIG. 8 is transmitted by the subtractor 34, and FIG. 9B is an output example of the adder 41. . In FIG. 9A, the fundamental frequency component 51 and the third harmonic component 53 remaining in the difference signal after subtraction are indicated by a solid line, and the removed second harmonic component 52 is indicated by a dotted line. Yes. In FIG. 9B, the second harmonic component 52 remaining in the sum signal after addition is indicated by a solid line, and the removed fundamental frequency component 51 and third harmonic component 53 are indicated by a dotted line. Yes.
送波時の超音波の周波数帯域は図8のように制限されているので、図9(a)のように受信信号の基本周波数の成分51はf0を中心にf0の2倍の周波数2f0より低い周波数の範囲に分布している。また、受信信号の3次高調波の成分53はf0の3倍の周波数3f0を中心に2f0より高い周波数の範囲に分布している。また、2次高調波の成分52のエネルギーの大きい2f0付近の成分と重なる部分が少ない。Since ultrasonic frequency band when transmitting is limited as shown in Figure 8, the frequency of two times f 0 component 51 of the fundamental frequency of the received signal around the f 0 as shown in FIG. 9 (a) 2f is distributed in a frequency range lower than 0 . The third-harmonic component 53 of the received signal is distributed in a frequency range higher than 2f 0 around a frequency 3f 0 that is three times f 0 . In addition, there are few portions that overlap with components near 2f 0 where the energy of the second harmonic component 52 is large.
このように、基本周波数の成分51と3次高調波の成分53は周波数帯域が重なっていないのでパルスインバージョンを用いて、図9(a)のように減算後は2次高調波の成分52を除去し、基本周波数の成分51と3次高調波の成分53を残すことができる。また、この後、基本波LPF36と3次高調波BPF35を通過させることにより、容易に基本周波数の成分51と3次高調波の成分53を分離できる。 As described above, since the frequency band of the fundamental frequency component 51 and the third harmonic component 53 do not overlap, the second harmonic component 52 is subtracted after subtraction as shown in FIG. The fundamental frequency component 51 and the third harmonic component 53 can be left. Thereafter, the fundamental frequency component 51 and the third harmonic component 53 can be easily separated by passing the fundamental LPF 36 and the third harmonic BPF 35.
同様に、基本周波数の成分51と3次高調波の成分53は周波数帯域が重なっていないのでパルスインバージョンを用いて、図9(b)のように加算後は基本周波数の成分51と3次高調波の成分53を除去し、2次高調波の成分52を残すことができる。また、この後、2次高調波BPF42を通過させることにより、容易に2次高調波の成分52を分離できる。 Similarly, since the fundamental frequency component 51 and the third harmonic component 53 do not overlap in frequency band, using the pulse inversion, the fundamental frequency component 51 and the third order component are added as shown in FIG. 9B. The harmonic component 53 can be removed, and the second harmonic component 52 can be left. Thereafter, the second harmonic component 52 can be easily separated by passing the second harmonic BPF 42.
なお、基本周波数f0より低い周波数成分はできるだけ広い周波数範囲で残すと伸張後の信号レベルを大きくすることができる。If the frequency component lower than the fundamental frequency f 0 is left in the widest possible frequency range, the signal level after expansion can be increased.
例えば、図10のように送波する超音波の周波数特性を(f0−f1)>(f2−f0)になるようにすれば良い。図10は、超音波探触子2から送波される超音波の周波数特性の別例を示すグラフである。For example, as shown in FIG. 10, the frequency characteristics of the ultrasonic wave to be transmitted may be set to (f 0 −f 1 )> (f 2 −f 0 ). FIG. 10 is a graph showing another example of frequency characteristics of ultrasonic waves transmitted from the ultrasonic probe 2.
例えば、f0が3MHzの場合、f1を0.5MHz、f2を4MHzにすると良い。f0−f1は2.5MHz、f2−f0は1MHzであり、(f0−f1)>(f2−f0)の条件を満たしている。For example, when f 0 is 3 MHz, f 1 may be 0.5 MHz and f 2 may be 4 MHz. f 0 -f 1 is 2.5 MHz and f 2 -f 0 is 1 MHz, which satisfies the condition of (f 0 -f 1 )> (f 2 -f 0 ).
また、超音波は高い周波数ほど被検体で減衰しやすいので、送信時に高い周波数ほど利得が高くなるようにしておくことが望ましい。例えば、図11のように超音波探触子2から送波される超音波の周波数特性を、基本周波数f0より周波数が高くなるにつれて基本周波数f0の利得G0より利得が増加し、基本周波数f0より周波数が低くなるにつれて利得G0より利得が減少する周波数範囲を有するようにすれば良い。図11の周波数特性例では、f0を含むf1からfBの間で利得が周波数に比例して増加している。Further, since ultrasonic waves are more likely to be attenuated by the subject at higher frequencies, it is desirable to increase the gain at higher frequencies during transmission. For example, the ultrasonic frequency characteristic transmitting from the ultrasound probe 2 as shown in FIG. 11, increased gain than the gain G 0 of the fundamental frequency f 0 as the frequency becomes higher than the fundamental frequency f 0, the basic A frequency range in which the gain decreases from the gain G 0 as the frequency becomes lower than the frequency f 0 may be provided. In the frequency characteristic example of FIG. 11, the gain increases in proportion to the frequency between f 1 and f B including f 0 .
例えば、f0が3MHz、f1を1MHz、f2を5MHzとするとfB=4.5MHzになるように構成すれば良い。For example, if f 0 is 3 MHz, f 1 is 1 MHz, and f 2 is 5 MHz, f B = 4.5 MHz may be configured.
このようにすると、高い周波数でも大きな受信信号が得られ、伸張後の信号レベルを大きくすることができる。 In this way, a large received signal can be obtained even at a high frequency, and the signal level after expansion can be increased.
以上このように、本発明によれば、分散圧縮による送受信を用いて対象とするn次高調波を抽出することができる。 As described above, according to the present invention, it is possible to extract a target n-order harmonic using transmission and reception by distributed compression.
1 送信処理部
2 超音波探触子
3 受信処理部
6 画像生成部
9 デジタルスキャンコンバータ
10 表示部
13 入力部
31 受信回路
32 A/D変換器
33 遅延部
34 減算器
35 3次高調波BPF
36 基本波LPF
39 不整合フィルタ
41 加算器
42 2次高調波BPF
96 記憶部
98 CPU
99 制御部
100 超音波診断装置DESCRIPTION OF SYMBOLS 1 Transmission processing part 2 Ultrasonic probe 3 Reception processing part 6 Image generation part 9 Digital scan converter 10 Display part 13 Input part 31 Reception circuit 32 A / D converter 33 Delay part 34 Subtractor 35 3rd harmonic BPF
36 fundamental wave LPF
39 Mismatch filter 41 Adder 42 Second harmonic BPF
96 storage unit 98 CPU
99 Control unit 100 Ultrasonic diagnostic apparatus
Claims (8)
前記超音波探触子から送波される超音波の基本周波数をf0、周波数帯域の上限の周波数をf2とすると、f2<2f0になるように構成されており、
前記超音波探触子から送波される超音波の音圧の利得は、基本周波数f 0 より周波数が高くなるにつれて増加し、基本周波数f 0 より周波数が低くなるにつれて減少する周波数範囲を有することを特徴とする超音波診断装置。 An ultrasonic probe that transmits ultrasonic waves to the subject, a first transmission signal that is distributed and compressed having a component of a desired fundamental frequency, and a second transmission signal that is an inversion of the first transmission signal, in this order. A transmission processing unit that generates and drives the ultrasound probe; a first reception signal that corresponds to the first transmission signal that is received by the ultrasound probe; and a second signal that corresponds to the second transmission signal. A reception processing unit that expands and outputs at least one of a difference signal or a sum signal from the received signal of 2; an image generation unit that generates an ultrasonic image using the expanded signal output from the reception processing unit; A display unit for displaying an ultrasonic image generated by the image generation unit, and an ultrasonic diagnostic apparatus comprising:
When the fundamental frequency of the ultrasonic wave transmitted from the ultrasonic probe is f 0 and the upper limit frequency of the frequency band is f 2 , f 2 <2f 0 is satisfied .
Gain of ultrasonic sound pressure that is transmitting from the ultrasound probe increases as the frequency than the fundamental frequency f 0 is higher, have a reduced frequency range as the frequency than the fundamental frequency f 0 is lowered An ultrasonic diagnostic apparatus characterized by the above.
前記第1の受信信号の送信を開始した時間と前記第2の受信信号の送信を開始した時間の時間差に相当する間、前記第1の受信信号を遅延させる遅延部と、
前記遅延部の出力と、前記第2の受信信号との差分を前記差分信号として算出する減算器と、
を有することを特徴とする請求項1または2に記載の超音波診断装置。 The reception processing unit
A delay unit that delays the first reception signal for a time difference between a time at which transmission of the first reception signal is started and a time at which transmission of the second reception signal is started;
A subtractor that calculates a difference between the output of the delay unit and the second received signal as the difference signal;
The ultrasonic diagnostic apparatus according to claim 1, comprising:
前記第1の受信信号の送信を開始した時間と前記第2の受信信号の送信を開始した時間の時間差に相当する間、前記第1の受信信号を遅延させる遅延部と、
前記遅延部の出力と、前記第2の受信信号との和を前記和信号として算出する加算器と、
を有することを特徴とする請求項1から3の何れか1項に記載の超音波診断装置。 The reception processing unit
A delay unit that delays the first reception signal for a time difference between a time at which transmission of the first reception signal is started and a time at which transmission of the second reception signal is started;
An adder that calculates the sum of the output of the delay unit and the second received signal as the sum signal;
The ultrasonic diagnostic apparatus according to any one of claims 1 to 3, wherein:
前記差分信号または前記和信号について変調符号列による分散圧縮を伸張する復調フィルタと、
前記復調フィルタによって伸張された信号の包絡線を検波して出力する包絡線検波部と、
を有することを特徴とする請求項3または4に記載の超音波診断装置。 The reception processing unit
A demodulation filter for expanding distributed compression by a modulation code string for the differential signal or the sum signal;
An envelope detector for detecting and outputting an envelope of the signal expanded by the demodulation filter;
The ultrasonic diagnostic apparatus according to claim 3, wherein:
互いに符号が反転関係にある1組のBarker符号を前記第1の送信信号および前記第2の送信信号として生成することを特徴とする請求項3から5の何れか1項に記載の超音波診断装置。 The transmission processing unit
The ultrasonic diagnosis according to any one of claims 3 to 5, wherein a pair of Barker codes whose signs are in an inverted relationship with each other are generated as the first transmission signal and the second transmission signal. apparatus.
前記第1の送信信号および前記第2の送信信号にPSK変調を行って出力することを特徴とする請求項6に記載の超音波診断装置。 The transmission processing unit
The ultrasonic diagnostic apparatus according to claim 6 , wherein the first transmission signal and the second transmission signal are subjected to PSK modulation and output .
互いに位相が反転関係にある1組のチャープ信号を前記第1の送信信号および前記第2の送信信号として生成することを特徴とする請求項3から5の何れか1項に記載の超音波診断装置。 The transmission processing unit
6. The ultrasonic diagnosis according to claim 3 , wherein a set of chirp signals whose phases are inverted with respect to each other are generated as the first transmission signal and the second transmission signal. 6. apparatus.
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JP2004520907A (en) * | 2001-01-11 | 2004-07-15 | ゼネラル・エレクトリック・カンパニイ | Harmonic Golay coded excitation with differential pulse generation for diagnostic ultrasound imaging |
JP2005211334A (en) * | 2004-01-29 | 2005-08-11 | Aloka Co Ltd | Ultrasonic diagnosis equipment |
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JPS5710512A (en) * | 1980-06-20 | 1982-01-20 | Fujitsu Ltd | Equalizing circuit |
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JP2004520907A (en) * | 2001-01-11 | 2004-07-15 | ゼネラル・エレクトリック・カンパニイ | Harmonic Golay coded excitation with differential pulse generation for diagnostic ultrasound imaging |
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