CN219613832U

CN219613832U - Photoacoustic ultrasonic data acquisition system with adjustable dynamic gain

Info

Publication number: CN219613832U
Application number: CN202320524732.5U
Authority: CN
Inventors: 张吴昱; 叶飞; 王巍
Original assignee: Guangdong Guangsheng Technology Co ltd
Current assignee: Guangdong Guangsheng Technology Co ltd
Priority date: 2023-03-17
Filing date: 2023-03-17
Publication date: 2023-09-01
Anticipated expiration: 2033-03-17

Abstract

The utility model discloses a photoacoustic ultrasonic data acquisition system with adjustable dynamic gain, which comprises a fixed gain amplifier, an adjustable gain amplifier, a time detection module, a circuit switching module and an analog-to-digital conversion module. The utility model has the advantages that the input analog signals are judged to belong to the photoacoustic signals or the ultrasonic signals through time, the weak photoacoustic signals are amplified by adopting the fixed gain of large gain, so that the lowest sensitivity of the analog-to-digital conversion module is achieved, the ultrasonic signals with higher intensity are amplified by adopting the adjustable gain of small gain, and the saturation distortion of the analog-to-digital conversion module is avoided. Finally, the intensity of the photoacoustic digital signal acquired by the computer is equivalent to that of the ultrasonic digital signal, so that the imaging requirement of the photoacoustic ultrasonic bimodal imaging system is met.

Description

Photoacoustic ultrasonic data acquisition system with adjustable dynamic gain

Technical Field

The utility model relates to the technical field of photoacoustic ultrasonic bimodal imaging, in particular to a photoacoustic ultrasonic data acquisition system with adjustable dynamic gain.

Background

Photoacoustic imaging is a new biomedical imaging method developed in recent years, both non-invasive and non-ionized. When pulsed laser light is irradiated into biological tissue, the light absorbing components of the tissue will generate an ultrasonic signal, which we call photoacoustic signal. The photoacoustic signal generated by the biological tissue carries the light absorption characteristic information of the tissue, and the light absorption distribution image in the tissue can be reconstructed by detecting the photoacoustic signal.

Due to the high selection characteristics of photoacoustic imaging, high-contrast images can be obtained, which also results in limited information acquired by the photoacoustic images, and the need for supplementing by ultrasonic imaging, such as acquiring the position information of a photoacoustic imaging target in biological tissues.

Ultrasonic waves can be excited to carry out ultrasonic imaging by the ultrasonic transducer used in the photoacoustic imaging, which means that the alternate excitation of the photoacoustic ultrasonic bimodal imaging system can be realized by only inserting ultrasonic pulse excitation between every two laser pulses, namely, the ultrasonic transducer is shared by the photoacoustic imaging and the ultrasonic imaging. However, this is premised on the ability of the data acquisition system to distinguish between photoacoustic signals and ultrasound signals.

In addition, the intensity of the photoacoustic analog signal is typically more than an order of magnitude lower than that of the ultrasound analog signal, and if a fixed gain data acquisition system commonly used in photoacoustic imaging systems is used, the acquired ultrasound imaging information will be saturated and distorted. Therefore, there is a need for a data acquisition system suitable for photoacoustic ultrasound bimodal imaging that employs large gain amplification for photoacoustic signals, while ultrasound signals employ adjustable small gain amplification.

Disclosure of Invention

The utility model aims to overcome the defects and shortcomings of the prior art, and provides a photoacoustic ultrasonic data acquisition system with adjustable dynamic gain, which can distinguish photoacoustic signals and ultrasonic signals obtained by alternate excitation and can avoid saturation distortion of the ultrasonic signals on the premise of ensuring sufficient amplification gain of the photoacoustic signals.

In order to achieve the purpose, the utility model adopts the following technical scheme that the photoacoustic ultrasonic data acquisition system with the adjustable dynamic gain comprises a fixed gain amplifier, an adjustable gain amplifier, a time detection module, a line switching module and an analog-to-digital conversion module.

The time detection module judges the analog signal to which the current time belongs based on the trigger signal, and the judging result is transmitted to the line switching module.

After the photoacoustic analog signal is input into the line switching module, the photoacoustic analog signal is transmitted to the fixed gain amplifier to amplify a large-gain signal; after being input into the circuit switching module, the ultrasonic analog signals are transmitted to the adjustable gain amplifier to amplify the signals with small gain.

The amplified photoacoustic analog signal and ultrasonic analog signal are converted into digital signals by an analog-to-digital conversion module.

As a preferable technical scheme, the gain multiple of the fixed gain amplifier is not lower than 50 dB; the adjustable gain amplifier may have a gain multiple adjustable range covering 10 to 30 dB.

As an optimal technical scheme, the time detection module utilizes a crystal oscillator and a counter to perform time detection, after each acquisition is started, the value of an output signal changes when the set time is reached, after the acquisition is finished, the output signal is restored to an initial value before the next acquisition is started; the crystal oscillator frequency is not lower than 50 MHz.

As an preferable technical scheme, the circuit switching module determines the subsequent circuit selection according to the output signal value of the time detection module, and the single switching time is lower than 800 ns.

As a preferable technical scheme, the sampling rate of the analog-to-digital conversion module is not lower than 125 MS/s.

Compared with the prior art, the utility model has the following advantages and beneficial effects: 1. according to the utility model, the time detection module is used for judging whether the analog signal belongs to the photoacoustic signal or the ultrasonic signal, so that the photoacoustic imaging and the ultrasonic imaging can share the ultrasonic transducer, and the structural complexity of the photoacoustic ultrasonic imaging system is greatly reduced. 2. The utility model adopts different amplification gain schemes for the photoacoustic signal and the ultrasonic signal, provides enough fixed amplification gain for the weak photoacoustic signal, amplifies the ultrasonic signal with the intensity higher by one order of magnitude, adopts smaller gain, has adjustable gain and avoids saturation distortion of the ultrasonic signal. Such a solution ensures the imaging quality of a photoacoustic ultrasound dual-modality imaging system.

Drawings

Fig. 1 is a schematic diagram of a dynamic gain adjustable photoacoustic ultrasound data acquisition system of the present utility model.

Fig. 2 is a photoacoustic signal and an ultrasound signal obtained with an embodiment of a dynamic gain adjustable photoacoustic ultrasound data acquisition system.

Description of the embodiments

The present utility model will be described in further detail with reference to examples and drawings, but embodiments of the present utility model are not limited thereto.

Examples

As shown in fig. 1, the present utility model discloses a photoacoustic ultrasound data acquisition system with adjustable dynamic gain, comprising: the device comprises a fixed gain amplifier, an adjustable gain amplifier, a time detection module, a line switching module and an analog-to-digital conversion module. The time detection module judges the analog signal to which the current time belongs based on the trigger signal, and the judging result is transmitted to the line switching module. After the photoacoustic analog signal is input into the line switching module, the photoacoustic analog signal is transmitted to the fixed gain amplifier to amplify a large-gain signal; after being input into the circuit switching module, the ultrasonic analog signals are transmitted to the adjustable gain amplifier to amplify the signals with small gain. The amplified photoacoustic analog signal and ultrasonic analog signal are converted into digital signals by an analog-to-digital conversion module.

The fixed gain amplifier is used for amplifying the photoacoustic analog signals with weaker strength with large gain; the adjustable gain amplifier is used for amplifying the ultrasonic analog signals with larger intensity by small gain, and an adjustable gain space is needed in consideration of different ultrasonic excitation intensities of different imaging depths; the time detection module is used for distinguishing the photoacoustic signal from the ultrasonic signal based on the trigger signal; the circuit switching module is used for rapidly switching to a preset circuit according to the distinguishing result of the time detection module; the analog-to-digital conversion module is used for converting the analog signals received in a period of time into digital signals based on the trigger signals.

The photoacoustic ultrasonic data acquisition system with adjustable dynamic gain in the utility model is further described below: the laser wavelength used was 532 nm; the parameters of the ultrasonic transducer are as follows: the main frequency is 30 MHz, -6 dB bandwidth is 80%, the central opening diameter is 3 mm, and the outer diameter is 8 mm; the imaging sample is a surgical blade; the trigger signal is a TTL signal with the repetition frequency of 10 kHz; the ultrasonic excitation voltage is +/-50V, and the gain value of the adjustable gain amplifier is set to 35 dB; the photoacoustic excitation pulse is delayed by 8 microseconds from the ultrasonic excitation pulse; the single acquisition time was 32 microseconds.

A fixed gain amplifier with a gain of 50 dB.

An adjustable gain amplifier having a gain of-2.5 dB to 42.5 dB.

The time detection module is used for detecting time by using the crystal oscillator and the counter, the output signal value is changed from an initial value 0 to 1 when the set time (8 microseconds) is reached after each acquisition is started, and the output signal is restored to the initial value 0 after the acquisition is finished and before the next acquisition is started; the crystal oscillator frequency is 50 MHz.

The circuit switching module judges the subsequent circuit selection according to the output signal value of the time detection module, and is connected with the adjustable gain amplifier when the signal value is 0 and is connected with the fixed gain amplifier when the signal value is 1. The single switching time was 500 ns.

And the sampling rate of the analog-digital conversion module is 125 MS/s.

From the figure, the photoacoustic ultrasonic data acquisition system with adjustable dynamic gain adjusts photoacoustic signals and ultrasonic signals which are different by more than one order of magnitude to acquire the photoacoustic signals and the ultrasonic signals by the same order of magnitude.

The above examples are preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present utility model should be made in the equivalent manner, and the embodiments are included in the protection scope of the present utility model.

Claims

1. The photoacoustic ultrasonic data acquisition system with the adjustable dynamic gain is characterized by comprising a fixed gain amplifier, an adjustable gain amplifier, a time detection module, a circuit switching module and an analog-to-digital conversion module;

the time detection module judges an analog signal to which the current time belongs based on the trigger signal, and the judging result is transmitted to the line switching module;

after the photoacoustic analog signal is input into the line switching module, the photoacoustic analog signal is transmitted to the fixed gain amplifier to amplify a large-gain signal; after the ultrasonic analog signal is input into the line switching module, the ultrasonic analog signal is transmitted to the adjustable gain amplifier to amplify the signal with small gain;

2. The dynamic gain-adjustable photoacoustic ultrasound data acquisition system of claim 1, wherein the fixed gain amplifier has a gain multiple of not less than 50 dB; the adjustable gain amplifier may have a gain multiple adjustable range covering 10 to 30 dB.

3. The photoacoustic ultrasonic data collection system of claim 1, wherein the time detection module performs time detection by using a crystal oscillator and a counter, changes the value of the output signal when a set time is reached after each collection is started, and restores the initial value of the output signal after the collection is completed and before the next collection is started; the crystal oscillator frequency is not lower than 50 MHz.

4. The photoacoustic ultrasound data acquisition system of claim 1, wherein the line switching module determines the subsequent line selection according to the output signal value of the time detection module, the single switching time being lower than 800 ns.

5. The dynamic gain adjustable photoacoustic ultrasound data acquisition system of claim 1, wherein the analog-to-digital conversion module has a sampling rate of not less than 125 MS/s.