WO2021036897A1 - 光声成像系统及方法 - Google Patents

光声成像系统及方法 Download PDF

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WO2021036897A1
WO2021036897A1 PCT/CN2020/110196 CN2020110196W WO2021036897A1 WO 2021036897 A1 WO2021036897 A1 WO 2021036897A1 CN 2020110196 W CN2020110196 W CN 2020110196W WO 2021036897 A1 WO2021036897 A1 WO 2021036897A1
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ultrasonic transducer
photoacoustic
dimensional
imaged
laser
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PCT/CN2020/110196
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English (en)
French (fr)
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田超
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中国科学技术大学
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A61B5/0075—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0093—Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy
    • A61B5/0095—Detecting, measuring or recording by applying one single type of energy and measuring its conversion into another type of energy by applying light and detecting acoustic waves, i.e. photoacoustic measurements
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/44—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device
    • A61B8/4483—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer
    • A61B8/4488—Constructional features of the ultrasonic, sonic or infrasonic diagnostic device characterised by features of the ultrasound transducer the transducer being a phased array
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/5207—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of raw data to produce diagnostic data, e.g. for generating an image
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/5269—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving detection or reduction of artifacts
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/06—Visualisation of the interior, e.g. acoustic microscopy
    • G01N29/0654—Imaging

Definitions

  • the present invention relates to the field of photoacoustic imaging technology, and more specifically, to a photoacoustic imaging system and method.
  • ultrasonic phase control technology uses electronic methods to control the deflection, focusing and scanning of the sound beam. It can scan quickly without moving or moving the transducer. It also has good sound beam accessibility and can be used for complex geometric shapes.
  • the detection of the object to be tested and its blind area can also optimize the control of the focus size, the depth of the focal area and the direction of the sound beam, so that the detection resolution and signal-to-noise ratio can be improved, so that the detection image is clearer and the detection speed is faster.
  • phased array ultrasonic transducer is the core component to realize the ultrasonic phase control technology.
  • the photoacoustic signal acquisition rate is low, the imaging sensitivity is low, and the imaging quality is poor.
  • the technical solution of the present invention provides a photoacoustic imaging system and method, which can increase the collection rate of photoacoustic signals, increase sensitivity, and have better imaging quality.
  • a photoacoustic imaging system includes:
  • the laser is used to emit laser pulses to illuminate the object to be imaged, and through the thermoelastic effect, excite the object to be imaged to generate a photoacoustic signal that propagates to a three-dimensional space;
  • a three-dimensional phased array ultrasonic transducer the three-dimensional phased array ultrasonic transducer is used to collect the photoacoustic signal propagating to a three-dimensional space; the three-dimensional phased array ultrasonic transducer has a cylindrical base, the cylindrical base An ultrasonic transducer array is fixed on it, and the ultrasonic transducer array includes multiple rows of ultrasonic transducer array elements surrounding the central axis of the cylindrical substrate; the axis is the midpoint of the top surface and the bottom surface of the cylindrical substrate. Point connection
  • a multi-channel data acquisition circuit where the multi-channel data acquisition circuit is used to perform signal processing on the photoacoustic signal collected by the three-dimensional phased array ultrasonic transducer;
  • a computer configured to form a three-dimensional photoacoustic image of the object to be imaged based on the photoacoustic signal after signal processing.
  • the laser pulses generated by the laser illuminate the object to be imaged through an optical fiber illumination system
  • the optical fiber illumination system includes: an optical fiber coupler and a multi-path optical fiber bundle; one end of the optical fiber bundle is coupled to the laser output port of the laser through the optical fiber coupler, and the other end of the multiple optical fiber bundles are all Distributed on the same circle, the circle surrounds the object to be imaged and provides uniform illumination for the object to be imaged.
  • the laser pulse generated by the laser illuminates the object to be imaged through a free optical path illumination system
  • the free light path illumination system includes: a diffuser, a conical lens, and a condenser. After the laser pulses generated by the laser pass through the diffuser, the conical lens, and the concentrator in sequence, illuminate the waiting Image the object.
  • the three-dimensional phased array ultrasonic transducer includes a plurality of ultrasonic transducer array elements
  • the multi-channel data acquisition circuit includes: a multi-channel amplifier, a multi-channel filter, and a multi-channel analog-to-digital converter; each ultrasonic transducer array element corresponds to a channel alone, and the ultrasonic transducer array element acquisition station
  • the photoacoustic signal is sequentially amplified, filtered and processed by analog-to-digital conversion through the corresponding channel, and then sent to the computer.
  • time division multiplexer between the multi-channel data acquisition circuit and the three-dimensional phased array ultrasonic transducer, and the time division multiplexer is used for time division of multi-channel signals. collection.
  • the columnar substrate has a through hole penetrating the top surface and the bottom surface thereof, and the ultrasonic transducer elements are fixed on the inner wall of the through hole;
  • the ultrasonic transducer array elements are all fixed on the outer surface of the cylindrical base.
  • the mechanical scanning device is used to drive the object to be imaged or the three-dimensional phased array ultrasonic transducer to move or translate along the axis Is to rotate around the axis.
  • the columnar substrate includes a plurality of detachable sub-columnar substrates
  • At least one row of the ultrasonic transducer array element is arranged on the sub-columnar base
  • a row of the ultrasonic transducer array elements are arranged on the sub-columnar base, and the number and distribution of the ultrasonic transducer array elements on the sub-column base are the same.
  • the present invention also provides a photoacoustic imaging method.
  • the photoacoustic imaging method includes:
  • the laser pulse emitted by the laser irradiates the object to be imaged, and through the thermoelastic effect, the object to be imaged is excited to generate a photoacoustic signal that propagates to the three-dimensional space;
  • the computer forms a three-dimensional photoacoustic image of the object to be imaged based on the photoacoustic signal processed by the signal.
  • the above-mentioned photoacoustic imaging method it further includes:
  • the processing speed of the collected multi-channel photoacoustic signals and images is improved.
  • the object to be imaged can be excited by a laser to generate a photoacoustic signal, and the photoacoustic signal can be collected by a three-dimensional phased array ultrasonic transducer.
  • the three-dimensional phased array ultrasonic transducer has a cylindrical base on which an ultrasonic transducer array is fixed, and the ultrasonic transducer array includes multiple rows of ultrasonic transducer array elements surrounding the central axis of the cylindrical base Therefore, the three-dimensional phased array ultrasonic transducer can collect photoacoustic signals propagating in three-dimensional space to realize three-dimensional imaging, and can increase the collection rate of photoacoustic signals, increase sensitivity, and have better imaging quality.
  • the invention can perform low-noise amplification, filtering and high-speed parallel analog-to-digital conversion on the captured multi-channel photoacoustic signal through the multi-channel data acquisition circuit, and then reconstruct, process and display the image through the computer, and can restore the absorber in the object to be imaged
  • the three-dimensional spatial distribution of the laser; multi-spectral imaging by scanning the laser wavelength can realize the non-invasive characterization of the chemical composition; by analyzing the frequency spectrum of the received ultrasound signal, the non-invasive characterization of the physical properties can be realized; through the GPU acceleration, the multi-channel signal and image can be improved Processing speed: Multi-row photoacoustic imaging can be realized, and three-dimensional volume images can be obtained at high speed, which solves the problem that traditional photoacoustic imaging can only perform two-dimensional tomographic imaging.
  • FIG. 1 is a schematic structural diagram of a photoacoustic imaging system provided by an embodiment of the present invention
  • FIG. 2 is a schematic diagram of the structure of a three-dimensional phased array ultrasonic transducer in the photoacoustic imaging system shown in FIG. 1;
  • Figure 3 is a schematic diagram of the structure of a conventional planar array multi-row photoacoustic transducer
  • FIG. 4 is a schematic diagram of the principle of another illumination system for laser irradiation of an object to be imaged in an embodiment of the present invention
  • FIG. 5 is a diagram of the sound field distribution of a single ultrasonic transducer array element in a 7.5MHz three-dimensional phased array ultrasonic transducer provided by an embodiment of the present invention
  • Fig. 6 is a sound field distribution diagram of a 7.5MHz three-dimensional phased array ultrasonic transducer in a set plane provided by an embodiment of the present invention
  • Figure 7 is a simulation model diagram of an object to be imaged
  • Figure 8 is the spatial distribution diagram of the photoacoustic field generated around the three-dimensional ball at 1.0 microsecond
  • Figure 9 is a photoacoustic signal distribution diagram collected by a simulated three-dimensional phased array ultrasonic transducer
  • Figure 10 is a three-dimensional small ball image reconstructed using the back-projection algorithm.
  • phased array ultrasound transducers In the field of medical ultrasound imaging and industrial non-destructive testing, there are three main types of phased array ultrasound transducers that are used more, namely linear array transducers, matrix transducers (area array transducers) and ring array transducers .
  • Multiple array elements in the linear array transducer are arranged in a straight line, and the sound field is distributed in a plane, and an image in a two-dimensional plane can be obtained.
  • Multiple array elements in the matrix transducer are arranged in a rectangular area, and the sound field is distributed in a three-dimensional rectangular space, which can image objects in the three-dimensional space.
  • the array elements in the ring array transducer are in a ring shape, arranged in concentric rings, and the sound field is also distributed in three-dimensional space, which can image objects in the three-dimensional space.
  • the above three phased array ultrasonic transducers have relatively simple shapes, low design and processing complexity, and controllable costs, which can meet the needs of most medical ultrasonic imaging and industrial non-destructive testing.
  • the emerging biomedical photoacoustic imaging technology is a non-invasive, high-resolution, high-contrast biomedical imaging modality that has developed rapidly in recent years.
  • Photoacoustic imaging has the advantages of high contrast of optical imaging and large penetration depth of ultrasound imaging. Microscopic imaging can reach a single organelle, and macroscopic imaging can reach all small animals. It can provide biological tissue structure, function, metabolism, molecular and genetic differences. Level of information. At present, most of the transducers used in photoacoustic imaging equipment directly borrow the linear array, matrix and ring array transducers in ultrasound imaging, but the principles of photoacoustic and ultrasound imaging are different, and direct borrowing is not an optimal signal receiving solution.
  • Ultrasound imaging is to transmit ultrasonic waves to the object to be imaged. Based on pulse echo, the ultrasonic waves emitted by the transducer are reflected by the tissue and then return to the original path to achieve imaging.
  • Linear or ring array transducers can meet most of the needs.
  • Photoacoustic imaging is based on the photothermal effect. The object to be imaged is irradiated by laser pulses. The photoacoustic signal generated by the laser excitation of the object to be imaged will propagate to three-dimensional space. The receiving strategy based on linear or ring array transducers will greatly lose useful signals. , Reduce image quality and imaging sensitivity.
  • an ultrasonic phased array transducer suitable for the three-dimensional space acquisition of photoacoustic signals can capture the photoacoustic signals in the space to the maximum extent, which is of great significance to the improvement of imaging quality.
  • the photoacoustic signal is ultrasound.
  • the ultrasonic wave generated by the object to be imaged is a photoacoustic signal.
  • photoacoustic imaging When photoacoustic imaging is used for medical ultrasound imaging, it can be used for biological imaging.
  • the main modalities include: X-ray computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), single photon emission Tomography (SPECT), ultrasound imaging and optical imaging, etc.
  • CT computed tomography
  • MRI magnetic resonance imaging
  • PET positron emission tomography
  • SPECT single photon emission Tomography
  • ultrasound imaging and optical imaging etc.
  • photoacoustic imaging has developed rapidly in recent years and has been applied to various research fields such as molecular imaging, cardiovascular disease research, drug metabolism, early tumor diagnosis, gene expression, stem cell and immunity, and brain neurobiology. , Provides more reliable and comprehensive experimental evidence for scientific research, and has broad application prospects.
  • Photoacoustic systems based on one-dimensional linear array transducers usually can only perform two-dimensional tomographic imaging of biological tissues.
  • Two-dimensional tomography has many problems in practical applications, such as the inability to obtain images that are perpendicular to the surface of the transducer, difficulty in registering and imaging certain targets (such as curved blood vessels, biopsy needles, etc.), and difficulty in quantitative evaluation of certain targets.
  • Volume such as three-dimensional tumor boundary, cardiac perfusion imaging
  • a mechanical scanning transducer is required, which will greatly reduce the imaging speed and cannot track certain dynamic changes in real time, such as heartbeat, blood flow, intervention, and perfusion imaging.
  • the area array transducer Compared with the linear array transducer, the area array transducer has one more dimension, which can capture the photoacoustic signal from the three-dimensional space at one time. Therefore, it is particularly suitable for spatial volume imaging and is the development of the next generation of photoacoustic imaging. direction.
  • the increase in the dimensions of the transducer and the number of array elements greatly increases the requirements for signal multi-channel acquisition and real-time processing capabilities, which makes the realization of the entire photoacoustic system difficult.
  • the only photoacoustic imaging system based on area array transducers in the world is the Nexus 128+ small animal photoacoustic imager.
  • the Nexus 128+ system is a photoacoustic imaging platform based on hemispherical transducers, which can achieve true three-dimensional imaging. Volume imaging, but the arrangement of transducers in the Nexus128+ system is sparse, and the number of 128 elements cannot cover the entire imaging space. During the experiment, mechanical scanning is required to increase the number of sampling points. Therefore, the imaging time resolution and spatial resolution are severely limited.
  • FIG. 1 is a photoacoustic imaging system provided by an embodiment of the present invention.
  • Figure 2 is the structure diagram of the three-dimensional phased array ultrasonic transducer in the photoacoustic imaging system shown in Figure 1.
  • the left picture in Fig. 2 is the overall view of the three-dimensional phased array ultrasonic transducer, and the right picture is A partial schematic diagram of a three-dimensional phased array ultrasonic transducer.
  • the photoacoustic imaging system includes: a laser 1, the laser 1 is used to emit laser pulses to illuminate the object 4 to be imaged, through the thermoelastic effect, to excite the object 4 to be imaged to generate a photoacoustic signal propagating to a three-dimensional space; three-dimensional phase control Array ultrasonic transducer 6, the three-dimensional phased array ultrasonic transducer 6 is used to collect the photoacoustic signal propagating to three-dimensional space; the three-dimensional phased array ultrasonic transducer 6 has a cylindrical base 21, the An ultrasonic transducer array is fixed on the cylindrical substrate 21, and the ultrasonic transducer array includes multiple rows of ultrasonic transducer elements 20 surrounding the central axis of the cylindrical substrate 21; the axis is the top of the cylindrical substrate 21.
  • the computer 14 is configured to form a three-dimensional photoacoustic image 15 of the object to be imaged based on the photoacoustic signal after signal processing.
  • the laser 1 may be a high-energy pulsed laser, which can emit nanosecond laser light.
  • the laser pulses generated by the laser 1 illuminate the object to be imaged 4 through a fiber illumination system; wherein, the fiber illumination system includes: a fiber coupler 2 and a multi-path fiber bundle 3; the fiber One end of the bundle 3 is coupled to the laser output port of the laser 1 through the optical fiber coupler 2, and the other ends of the multiple optical fiber bundles 3 are all distributed on the same circle, and the circle surrounds the object 4 to be imaged.
  • the object 4 to be imaged provides uniform illumination.
  • the optical fiber bundle 3 is arranged around the object 4 to be imaged, and one end of its output laser pulse evenly surrounds the object 4 to be imaged, so as to provide uniform illumination for the object 4 to be imaged.
  • the laser pulse generated by the laser 1 can be coupled to the fiber coupler 2 through a reflection device 19.
  • the optical fiber coupler 2 may include a telescope system, that is, the optical fiber coupler 2 may be realized by a telescope system.
  • FIG. 4 is a schematic diagram of the principle of another illumination system for laser irradiation of an object to be imaged in an embodiment of the present invention.
  • the laser pulse generated by the laser 1 passes through a free optical path
  • the illumination system illuminates the object to be imaged;
  • the free light path illumination system includes: a diffuser 16, a conical lens 17, and a condenser 18.
  • the laser pulses generated by the laser 1 pass through the diffuser 16, the After the conical lens 17 and the condenser 18, the object 4 to be imaged is illuminated.
  • the three-dimensional phased array ultrasonic transducer 6 includes a plurality of ultrasonic transducer array elements 20; each of the ultrasonic transducer array elements 20 collects a photoacoustic signal, and each photoacoustic signal corresponds to a signal processing channel.
  • the photoacoustic signal generated by the object 4 to be imaged propagates to the three-dimensional space through the coupling medium 5, and is finally captured and collected by the three-dimensional phased array ultrasonic transducer 6.
  • the coupling medium 5 can be air or liquid medium or solid medium. Among them, the synchronization between the laser 1 and the multi-channel data acquisition circuit 10 is realized by the trigger signal 16 of the laser 1.
  • the columnar substrate 21 has a through hole penetrating the top surface and the bottom surface thereof, and the ultrasonic transducer element 20 is fixed on the inner wall of the through hole.
  • the ultrasonic transducer elements 20 may be fixed on the outer surface of the cylindrical base 21.
  • the cylindrical base 21 may be a solid cylinder or a hollow cylinder.
  • the columnar base 21 has opposite top and bottom surfaces and side surfaces, and its axis is a line connecting the midpoint of the top surface and the midpoint of the bottom surface, and the top surface and the bottom surface are the same.
  • the columnar base 21 may be a cylinder or a square cylinder.
  • the traditional matrix transducer is shown in Figure 3.
  • Figure 3 is a schematic diagram of a conventional planar array multi-row photoacoustic transducer 30, which can only receive photoacoustic signals in a specific plane for two-dimensional tomographic imaging.
  • the three-dimensional phased array ultrasonic transducer 6 has multiple rows of ultrasonic transducer array elements 20 surrounding the axis of the cylindrical substrate 21, which can collect photoacoustic signals propagating in three-dimensional space, and is not limited to photoacoustic signals in a specific plane.
  • the signal can capture the photoacoustic signal propagating in the three-dimensional space at one time to obtain the three-dimensional volume image of the object 4 to be imaged, and realize multi-row photoacoustic imaging to obtain the three-dimensional volume image of the object 4 to be imaged.
  • the photoacoustic imaging system further includes: a mechanical scanning device for driving the object 4 to be imaged or the three-dimensional phased array ultrasonic transducer 6 to translate along the axis Or rotate around the axis.
  • the mechanical scanning device is not shown in FIG. 1. Through the relative movement of the object 4 to be imaged and the three-dimensional phased array ultrasonic transducer 6, the entire object 4 to be imaged can be scanned and a comprehensive photoacoustic imaging can be performed on it.
  • the computer 14 includes a three-dimensional image reconstruction system 11, a three-dimensional image processing system 12 and a three-dimensional image display system 13.
  • the nanosecond laser emitted by a high-energy pulsed laser is used to excite the object 4 to be imaged.
  • the absorber in the object 4 to be imaged absorbs the laser energy, and the temperature rises instantaneously. Due to the thermoelastic effect, Generate an ultrasonic signal (photoacoustic signal) and propagate to three-dimensional space.
  • a three-dimensional phased array ultrasonic transducer 6 with a high-density multi-row ultrasonic transducer array element 20 is used to receive the photoacoustic signal in the three-dimensional space, and the captured multi-channel photoacoustic signal is amplified, filtered and high-speed paralleled with low noise.
  • the analog-to-digital conversion processing, and finally the image reconstruction, processing and display can restore the three-dimensional spatial distribution of the absorber in the object 4 to be imaged.
  • the non-invasive characterization of the physical properties of the object 4 to be imaged can be realized.
  • GPU acceleration the processing speed of multi-channel signals and images can be improved.
  • the real-time processing and image reconstruction of the multi-channel high-dimensional signals generated in the system can be implemented by GPU acceleration methods.
  • GPU-accelerated hardware can be implemented using GPU graphics cards (such as the NVIDIA Tesla series), which has multiple stream processors, and each stream processor is configured with multiple processing cores.
  • GPU-accelerated software can be completed by using the C language-based CUDA (Compute Unified Device Architecture) parallel computing architecture.
  • CUDA parallel computing programs usually include a host program and multiple threads. The host program is first executed by the central processing unit CPU, and then each computing thread is started at the same time.
  • the photoacoustic signal excited by the laser to the object 4 to be imaged will propagate in a three-dimensional space, and will not be limited to a specific plane.
  • Traditional photoacoustic imaging systems based on linear arrays or transducer arrays usually can only receive photoacoustic signals in a specific plane for two-dimensional tomographic imaging.
  • the photoacoustic imaging system can capture the photoacoustic signal propagating in the three-dimensional space at one time to obtain the three-dimensional volume image of the object 4 to be imaged, and can realize multi-row photoacoustic imaging to obtain the three-dimensional volume image of the object 4 , Can achieve three-dimensional volume imaging at one time, while improving the signal-to-noise ratio, imaging sensitivity and imaging quality, and solve the problem that traditional photoacoustic imaging systems can only perform two-dimensional tomographic imaging and the imaging angle of view is limited.
  • Fig. 5 is a sound field distribution diagram of a single ultrasonic transducer element in a 7.5MHz three-dimensional phased array ultrasonic transducer provided by an embodiment of the present invention.
  • Fig. 5 shows a three-dimensional phased array ultrasonic transducer.
  • Figure 6 is a sound field distribution diagram of a 7.5MHz three-dimensional phased array ultrasonic transducer provided by an embodiment of the present invention in a set plane. It can be seen from Figure 6 that the three-dimensional phased array ultrasonic transducer 6 The sound field distribution of all ultrasonic transducer elements 20 in a specific plane, it can be seen that the maximum amplitude of the sound field appears in the center and is symmetrically distributed.
  • the above-mentioned three-dimensional phased array ultrasonic transducer 6 for simulation uses more ultrasonic transducer elements 20 in the height direction and the radial direction.
  • the restriction on reconstruction artifacts can be appropriately relaxed to greatly reduce the number of ultrasonic transducer elements 20.
  • laser 1 is an optical parametric amplification (OPO) laser with output wavelengths ranging from 690-950nm and 1200-2400nm, the time width of a single pulse is about 6ns, and the repetition frequency is 10Hz.
  • the numerical simulation used in the simulation is a three-dimensional small ball numerical model, including 8 small balls with a diameter of 1.2mm and a large ball with a diameter of 1.6mm, as shown in Figure 7.
  • Figure 7 is a simulation model diagram of the object to be imaged
  • the simulation model is a three-dimensional small ball simulation model.
  • FIG. 10 is a photoacoustic signal distribution diagram collected by a simulated three-dimensional phased array ultrasonic transducer. In Figure 9, the horizontal axis is time, and the vertical axis is the number of transducer elements. Figure 10 is a three-dimensional small ball image reconstructed using the back-projection algorithm. It can be seen that by using the photoacoustic imaging system described in the technical scheme of the present invention, three-dimensional imaging of an object can be accurately realized.
  • another embodiment of the present invention also provides a photoacoustic imaging method, which can be implemented by the photoacoustic imaging system described in the foregoing embodiment.
  • the photoacoustic imaging Methods include:
  • Step S11 The object to be imaged is irradiated by the laser pulse emitted by the laser, and the object to be imaged is excited to generate a photoacoustic signal propagating to the three-dimensional space through the thermoelastic effect.
  • a high-energy pulsed laser can be used to emit nanosecond lasers to excite the object to be imaged, so that the absorber in the object to be imaged absorbs the laser energy, and the temperature rises instantaneously. Due to the thermoelastic effect, a pressure ultrasonic signal (photoacoustic signal) is generated. Three-dimensional space propagation.
  • Step S12 Collect the photoacoustic signal propagating to the three-dimensional space through a three-dimensional phased array ultrasonic transducer.
  • a three-dimensional phased array ultrasonic transducer 6 with a high-density multi-row ultrasonic transducer array element 20 is used to receive a photoacoustic signal propagating in a three-dimensional space, and the signal is triggered by a synchronization signal output by a laser.
  • Step S13 Perform signal processing on the photoacoustic signal collected by the three-dimensional phased array ultrasonic transducer through a multi-channel data collection circuit.
  • this step after low-noise amplification, filtering and high-speed parallel analog-to-digital conversion are performed on the obtained multi-channel photoacoustic signal, it is transmitted to a computer for photoacoustic imaging.
  • Step S14 forming a three-dimensional photoacoustic image of the object to be imaged by the computer based on the photoacoustic signal processed by the signal.
  • the computer performs image reconstruction, image processing and image display on the discrete photoacoustic signal to restore the three-dimensional spatial distribution of the absorber in the sample.
  • the laser wavelength emitted by the laser can be adjusted, and the laser wavelength can be scanned in the ultraviolet, visible, and near-infrared bands to perform multi-spectral imaging, and perform imaging based on spectral images.
  • Non-invasive characterization of the chemical composition of the object that is, scanning the object to be imaged through the corresponding band laser, and processing the photoacoustic signal collected by the three-dimensional phased array ultrasonic transducer through the multi-channel data acquisition circuit, and the computer can also be based on The photoacoustic signal after signal processing is subjected to multispectral imaging.
  • the photoacoustic imaging method described in the embodiment of the present invention may use a GPU acceleration method to increase the processing speed of multi-channel signals and images in the photoacoustic imaging system.

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Abstract

一种光声成像系统及方法，可以通过激光器（1）激发待成像物体（4）产生光声信号，并通过三维相控阵超声换能器（6）采集向三维空间传播的光声信号，实现三维成像，且可以提高对光声信号的采集率，具有较好的成像质量。该系统对捕获的多通道光声信号进行低噪声放大、滤波和高速并行模数转换，对图像进行重建、处理和显示，可以恢复待成像物体（4）中吸收体的三维空间分布；通过扫描激光波长进行多光谱成像，可以实现化学成分的无创表征；通过分析接收超声信号的频谱，可以实现物理性质的无创表征；通过GPU加速，可以提升多路信号和图像的处理速度；可以实现多排光声成像，高速得到三维容积图像，解决了传统光声成像通常只能进行二维断层成像的问题。

Description

光声成像系统及方法
本申请要求于2019年08月23日提交中国专利局、申请号为201910784911.0、发明名称为“光声成像系统及方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及光声成像技术领域，更具体的说，涉及一种光声成像系统及方法。
背景技术
与传统的超声检测技术相比，超声相控技术具有很多的优点。超声相控技术采用电子方法控制声束偏转、聚焦和扫描，可以在不移动或少移动换能器的情况下进行快捷的扫描，而且具有良好的声束可达性，能对复杂几何形状的待测物体及其盲区进行检测，还可以通过优化控制焦点尺寸、焦区深度和声束方向，使得检测分辨率和信噪比等性能得到提高，使得检测图像更加清晰，使得检测速度更加快速。
由于具有上述优点，基于超声相控技术的光声成像系统及方法被广泛的应用于医学超声成像以及工业无损检测等领域。相控阵超声换能器是实现超声相控技术的核心部件，现有的相控阵超声换能器用于光声成像时，对光声信号采集率较低，成像灵敏度低，且成像质量差。
发明内容
有鉴于此，本发明技术方案提供了一种光声成像系统及方法，可以提高对光声信号的采集率，提高了灵敏度，具有较好的成像质量。
为了实现上述目的，本发明提供如下技术方案：
一种光声成像系统，所述光声成像系统包括：
激光器，所述激光器用于出射激光脉冲，以照射待成像物体，通过热弹效应，激发待成像物体产生向三维空间传播的光声信号；
三维相控阵超声换能器，所述三维相控阵超声换能器用于采集向三维空间传播的所述光声信号；所述三维相控阵超声换能器具有柱状基底，所述柱状基底上固定有超声换能器阵列，所述超声换能器阵列包括多排环绕所述柱状基底中轴线的超声换能器阵元；所述轴线为所述柱状基底的顶面中点与底面中点连线；
多通道数据采集电路，所述多通道数据采集电路用于将所述三维相控阵超声换能器采集的所述光声信号进行信号处理；
计算机，所述计算机用于基于信号处理后的所述光声信号，形成所述待成像物体的三维光声图像。
优选的，在上述光声成像系统中，所述激光器产生的激光脉冲通过光纤照明系统照射所述待成像物体；
其中，所述光纤照明系统包括：光纤耦合器以及多路光纤束；所述光纤束的一端通过所述光纤耦合器耦合至所述激光器的激光输出端口，多路所述光纤束的另一端均分布于同一圆周，所述圆周包围所述待成像物体，为所述待成像物体提供均匀照明。
优选的，在上述光声成像系统中，所述激光器产生的激光脉冲通过自由光路照明系统照射所述待成像物体；
所述自由光路照明系统包括：漫射器、圆锥透镜以及聚光器，所述激光器产生的激光脉冲依次通过所述漫射器、所述圆锥透镜以及所述聚光器后，照射所述待成像物体。
优选的，在上述光声成像系统中，所述三维相控阵超声换能器包括多个超声换能器阵元；
所述多通道数据采集电路包括：多通道放大器、多通道滤波器以及多通道模数转换器；每个所述超声换能器阵元单独对应一个通道，所述超声换能器阵元采集所述光声信号经过对应通道依次进行放大、滤波和模数转换处理后，发送给所述计算机。
优选的，在上述光声成像系统中，所述多通道数据采集电路与所述三维相 控阵超声换能器之间具有时分复用器，所述时分复用器用于多通道信号的分时采集。
优选的，在上述光声成像系统中，所述柱状基底具有贯穿其顶面和底面的通孔，所述超声换能器阵元均固定在所述通孔的内壁；
或，所述超声换能器阵元均固定在所述柱状基底的外侧面。
优选的，在上述光声成像系统中，还包括：机械扫描装置，所述机械扫描装置用于带动所述待成像物体或是所述三维相控阵超声换能器沿所述轴线平动或是绕所述轴线转动。
优选的，在上述光声成像系统中，所述柱状基底包括多个可拆分的子柱状基底；
所述子柱状基底上至少设置一排所述超声换能器阵元；
或所述子柱状基底上均设置一排所述超声换能器阵元，所述子柱状基底上所述超声换能器阵元的数量以及分布相同。
本发明还提供了一种光声成像方法，所述光声成像方法包括：
通过激光器出射的激光脉冲照射待成像物体，通过热弹效应，激发待成像物体产生向三维空间传播的光声信号；
通过三维相控阵超声换能器采集向三维空间传播的所述光声信号；
通过多通道数据采集电路将所述三维相控阵超声换能器采集的所述光声信号进行信号处理；
通过计算机基于信号处理后的所述光声信号，形成所述待成像物体的三维光声图像。
优选的，在上述光声成像方法中，还包括：
在紫外、可见光和红外波长范围内，通过扫描激光波长，进行多光谱成像，基于光谱图像进行所述待成像物体的化学成分的无创表征；
或，对所述三维相控阵超声换能器中多排超声换能器阵元接收到的超声信号在傅里叶域进行频谱分析，基于频谱分析结果，对所述待成像物体的物理性质进行无创表征；
或，通过GPU加速方法，提升所采集的多路光声信号和图像的处理速度。
通过上述描述可知，本发明技术方案提供的光声成像系统及方法中，可以通过激光器激发待成像物体产生光声信号，并通过三维相控阵超声换能器采集所述光声信号，由于所述三维相控阵超声换能器具有柱状基底，所述柱状基底上固定有超声换能器阵列，所述超声换能器阵列包括多排环绕所述柱状基底中轴线的超声换能器阵元，故所述三维相控阵超声换能器能够采集向三维空间传播的光声信号，实现三维成像，且可以提高对光声信号的采集率，提高了灵敏度，具有较好的成像质量。本发明可以通过多通道数据采集电路对捕获的多通道光声信号进行低噪声放大、滤波和高速并行模数转换，再通过计算机对图像进行重建、处理和显示，可以恢复待成像物体中吸收体的三维空间分布；通过扫描激光波长进行多光谱成像，可以实现化学成分的无创表征；通过分析接收超声信号的频谱，可以实现物理性质的无创表征；通过GPU加速，可以提升多路信号和图像的处理速度；可以实现多排光声成像，高速得到三维容积图像，解决了传统光声成像通常只能进行二维断层成像的问题。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据提供的附图获得其他的附图。
图1为本发明实施例提供的一种光声成像系统的结构示意图；
图2为图1所示光声成像系统中三维相控阵超声换能器的结构示意图；
图3为一种常规平面阵多排光声换能器的结构示意图；
图4为本发明实施例中另一种照明系统对待成像物体进行激光照射的原理示意图；
图5为本发明实施例提供的一种7.5MHz三维相控阵超声换能器中单个超声换能器阵元的声场分布图；
图6为本发明实施例提供的一种7.5MHz三维相控阵超声换能器在设定平面内的声场分布图；
图7为待成像物体的仿真模型图；
图8为1.0微秒时刻三维小球周围产生的光声场空间分布图；
图9为模拟三维相控阵超声换能器采集得到的光声信号分布图；
图10为利用反投影算法重建的三维小球图像。
具体实施方式
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
为使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图和具体实施方式对本发明作进一步详细的说明。
在医学超声成像和工业无损检测领域中，使用较多的相控阵超声换能器主要有三种，即线阵换能器、矩阵换能器(面阵换能器)和环阵换能器。线阵换能器中的多个阵元成直线排列，声场分布在一个平面内，可以得到二维平面内的图像。矩阵换能器中的多个阵元排布于矩形区域，声场分布于三维矩形空间，可以对三维空间内的物体进行成像。环阵换能器中的阵元呈环形，按同心圆环排列，声场也分布于三维空间，可以对三维空间内的物体进行成像。以上三种相控阵超声换能器形状较为简单，设计和加工复杂度不高，成本可控，可以满足大多数医学超声成像和工业无损检测的需求。
基于由光至声的能量转换，新兴的生物医学光声成像技术是近年来快速发展的一种无创、高分辨率、高对比度生物医学成像模态。光声成像具备了光学成像高对比度和超声成像大穿透深度的优点，微观成像可至单个细胞器，宏观成像可至小动物全体，并可提供生物组织结构、功能、代谢、分子和遗传等不同层面的信息。目前光声成像装备中采用的换能器大多是直接借用超声成像中的线阵、矩阵和环阵换能器，但光声与超声成像原理不同，直接借用并非最优 的信号接收方案。超声成像是向待成像物体发射超声波，基于脉冲回波，由换能器发射的超声波被组织反射后原路返回实现成像，线阵或环阵换能器可以满足绝大多数需求。光声成像基于光热效应，通过激光脉冲照射待成像物体，待成像物体由于激光激发产生的光声信号会向三维空间传播，基于线阵或环阵换能器的接收策略会极大损失有用信号，降低图像质量和成像灵敏度。设计适合于光声信号三维空间采集的超声相控阵换能器，最大限度捕获空间中的光声信号，对成像质量的提升有重要意义。其中，光声信号为超声波。激光激发待成像物体时，待成像物体产生的超声波为光声信号。
光声成像用于医学超声成像时，可以用于对生物成像，主要模态包括：X射线计算断层成像(CT)、磁共振成像(MRI)、正电子发射断层成像(PET)、单光子发射断层成像(SPECT)、超声成像和光学成像等。光声成像作为一种新兴的成像模态，近年来发展迅速，已经应用于分子影像、心血管疾病研究、药物代谢、肿瘤早期诊断、基因表达、干细胞及免疫、脑神经生物学等各研究领域，为科学研究提供了更可靠全面的实验证据，具有广阔的应用前景。
基于一维线阵换能器的光声系统通常只能对生物组织进行二维断层成像。二维断层成像在实际应用中存在许多问题，如无法得到与换能器表面垂直平面的图像、难以对某些目标(如弯曲的血管、活检针头等)进行配准成像、难以定量评估某些体积量(如肿瘤三维边界、心脏灌注成像)等。要利用一维线阵换能器实现三维体积成像，需要机械扫描换能器，这会大大降低成像速度，无法实时跟踪某些动态变化过程，如心跳、血流、介入、灌注成像等。
相较于线阵换能器，面阵换能器在维度上多出一维，可以一次性捕获来自三维空间的光声信号，因而特别适合于空间体积成像，是下一代光声成像的发 展方向。但换能器维度和阵元数目的增加，对信号多通道采集和实时处理能力的要求大大提升，这使得整个光声系统实现困难。目前国际上基于面阵换能器的光声成像系统只有Nexus 128+小动物光声成像仪，Nexus 128+系统是基于半球形换能器的光声成像平台，其可以实现真正意义上的三维体积成像，但Nexus128+系统中换能器排布稀疏，128个阵元数目无法覆盖整个成像空间，实验过程中需要进行机械扫描以增加采样点数，成像时间分辨率和空间分辨率因此严重受限。
为了解决上述问题，本发明实施例技术方案提供了一种光声成像系统，该光声成像系统如图1和图2所示所示，图1为本发明实施例提供的一种光声成像系统的结构示意图，图2为图1所示光声成像系统中三维相控阵超声换能器的结构示意图，图2中左图为三维相控阵超声换能器的整体视图，右图为三维相控阵超声换能器的局部示意图。
该光声成像系统包括：激光器1，所述激光器1用于出射激光脉冲，以照射待成像物体4，通过热弹效应，激发待成像物体4产生向三维空间传播的光声信号；三维相控阵超声换能器6，所述三维相控阵超声换能器6用于采集向三维空间传播的所述光声信号；所述三维相控阵超声换能器6具有柱状基底21，所述柱状基底21上固定有超声换能器阵列，所述超声换能器阵列包括多排环绕所述柱状基底21中轴线的超声换能器阵元20；所述轴线为所述柱状基底21的顶面中点与底面中点连线；多通道数据采集电路10，所述多通道数据采集电路10用于将所述三维相控阵超声换能器采集的所述光声信号进行信号处理；计算机14，所述计算机14用于基于信号处理后的所述光声信号，形成所述待成像物体的三维光声图像15。
所述激光器1可以为高能脉冲激光器，可以出射纳秒激光。图1所示方式中，所述激光器1产生的激光脉冲通过光纤照明系统照射所述待成像物体4；其中，所述光纤照明系统包括：光纤耦合器2以及多路光纤束3；所述光纤束3的一端通过所述光纤耦合器2耦合至所述激光器1的激光输出端口，多路所述光纤束3的另一端均分布于同一圆周，所述圆周包围所述待成像物体4，为 所述待成像物体4提供均匀照明。也就是说，所述光纤束3排布于待成像物体4的周围，其输出激光脉冲的一端均匀环绕待成像物体4，以为所述待成像物体4提供均匀照明。其中，所述激光器1产生的激光脉冲可以通过一反射器件19耦合到光纤耦合器2。光纤耦合器2可以包括望远镜系统，也就是说光纤耦合器2可以通过望远镜系统实现。
其他方式中，还可以如图4所示，图4为本发明实施例中另一种照明系统对待成像物体进行激光照射的原理示意图，该方式中，所述激光器1产生的激光脉冲通过自由光路照明系统照射所述待成像物体；所述自由光路照明系统包括：漫射器16、圆锥透镜17以及聚光器18，所述激光器1产生的激光脉冲依次通过所述漫射器16、所述圆锥透镜17以及所述聚光器18后，照射所述待成像物体4。
所述三维相控阵超声换能器6包括多个超声换能器阵元20；每一个所述超声换能器阵元20采集一路光声信号，每一路光声信号对应一个信号处理通道。待成像物体4产生的光声信号通过耦合介质5向三维空间传播，最后被三维相控阵超声换能器6捕获采集，耦合介质5可以为空气或是液体介质或是固体介质。其中，激光器1与多通道数据采集电路10之间的同步有激光器1的触发信号16实现。
所述多通道数据采集电路10为高速并行数据采集电路。所述多通道数据采集电路10包括：多通道放大器7、多通道滤波器8以及多通道模数转换器9；每个所述超声换能器阵元20单独对应一个通道，所述超声换能器阵元20采集的所述光声信号经过对应通道依次进行放大、滤波和模数转换处理后，发送给所述计算机14。可选的，所述多通道数据采集电路10与所述三维相控阵超声换能器6之间具有时分复用器，所述时分复用器用于多通道信号的分时采集。图1中未示出所述时分复用器。
在图2和所示方式中，所述柱状基底21具有贯穿其顶面和底面的通孔，所述超声换能器阵元20均固定在所述通孔的内壁。其他方式中，还可以设置所述超声换能器阵元20均固定在所述柱状基底21的外侧面，此时，所述柱状基底21可以为实心柱体或是空心柱体。所述柱状基底21具有相对的顶面和底面以及侧面，其轴线为顶面中点和底面中点连线，顶面和底面相同。所述柱状 基底21可以为圆柱体或是方柱体。而传统矩阵换能器如图3所示，图3为一种常规平面阵多排光声换能器30的结构示意图，只能接收特定平面内的光声信号，进行二维断层成像，而本发明实施所述三维相控阵超声换能器6具有多排包围柱状基底21轴线的超声换能器阵元20，可以采集在三维空间传播的光声信号，不限于特定平面内的光声信号，可以一次性捕获三维空间中传播的光声信号，得到待成像物体4的三维体积图像，可以实现多排光声成像，得到待成像物体4的三维体积图像。
如图2和所示，所述柱状基底21包括多个可拆分的子柱状基底110；所述子柱状基底110上至少设置一排所述超声换能器阵元20。可选的，所述子柱状基底110上均设置一排所述超声换能器阵元20，所述子柱状基底110上所述超声换能器阵元20的数量以及分布相同。所述柱状基底21上，所述超声换能器阵元20形成三维相控阵，相邻两个超声换能器阵元20之间具有一定间隔，所述超声换能器阵元20可以独立工作。
可选的，所述光声成像系统还包括：机械扫描装置，所述机械扫描装置用于带动所述待成像物体4或是所述三维相控阵超声换能器6沿所述轴线平动或是绕所述轴线转动。图1中未示出所述机械扫描装置。通过所述待成像物体4与所述三维相控阵超声换能器6的相对运动，可以完成扫描整个待成像物体4，对其进行全面的光声成像。
所述光声成像系统中，所述计算机14包括：三维图像重建系统11、三维图像处理系统12以及三维图像显示系统13。
本发明实施例所述光声成像系统中，利用高能脉冲激光器出射的纳秒激光激发待成像物体4，待成像物体4中的吸收体吸收激光能量，瞬间产生温度升高，由于热弹效应，产生超声波信号(光声信号)，向三维空间传播。利用具有高密度多排超声换能器阵元20的三维相控阵超声换能器6接收三维空间中的光声信号，在对捕获的多通道光声信号进行低噪声放大、滤波和高速并行模数转换处理，最后对图像进行重建、处理和显示，可以恢复待成像物体4中吸收体的三维空间分布。
通过扫描激光波长进行多光谱成像，可以实现样品化学成分的无创表征。由于不同分子的吸收光谱不同，可以利用光谱解混算法从多光谱图像中分离不同的分子，实现分子特异性成像。由于不同待成像物体4在吸收激光能量后产生的超声信号频率不同，通过对三维相控阵超声换能器6接收到的超声信号进行频谱分析，可以得到反映样品物理性质的参数，包括斜率和截距等，进而实现样品的无创表征。通过分析具有高密度多排超声换能器阵元20的三维相控阵超声换能器6接收超声信号的频谱，可以实现待成像物体4物理性质的无创表征。
通过GPU加速，可以提升多通道信号和图像的处理速度。系统中产生的多通道高维信号的实时处理和图像重建可采用GPU加速方法实现。GPU加速的硬件可以利用GPU显卡实现(如NVIDIA Tesla系列)，其具有多个流式处理器，每个流式处理器配置有多个处理内核。GPU加速的软件可以利用基于C语言的CUDA(Compute Unified Device Architecture)并行计算架构完成。CUDA并行计算程序通常包含一个主机程序和多个线程。主机程序首先由中央处理器CPU执行，随后同时启动各个计算线程。
在进行光声成像时，激光激发待成像物体4的光声信号会在三维空间传播，而不会局限在特定平面。传统基于线阵或换阵换能器阵列的光声成像系统通常只能接收特定平面内的光声信号，进行二维断层成像。本发明实施例所述光声成像系统可以一次性捕获三维空间中传播的光声信号，得到待成像物体4的三维体积图像，可以实现多排光声成像，得到待成像物体4的三维体积图像，可以一次性实现三维体积成像，同时提高了信噪比、成像灵敏度和成像质量，解决了传统光声成像系统通常只能进行二维断层成像以及成像视角受限的问题。
本发明实施例中，对所述光声成像系统进行了仿真实验，以说明本发明实施例所述光声成像系统的优势。
本发明实施例所述光声成像系统中，设置柱状基底21为圆筒结构，即具有贯穿顶面和底面通孔的圆柱结构，圆筒的内径为50mm，高度为200mm，高度方向上超声换能器阵元20排数为1496，同一排中超声换能器阵元20的数目为800。超声换能器阵元20的功能面为矩形，该矩形的高度为0.13mm，宽 度为0.16mm，间距0.04mm。所述三维相控阵超声换能器6的中心频率为7.5MHz，具有-6dB的灵敏度，带宽约为80％。
为了研究三维相控阵超声换能器6的声场分布特性，利用开源软件Field II进行了仿真。
如图5所示，图5为本发明实施例提供的一种7.5MHz三维相控阵超声换能器中单个超声换能器阵元的声场分布图，图5示出了三维相控阵超声换能器6中特定一个超声换能器阵元20在20mm×20mm平面内的声压级分布图，由图5可知，声场中存在主瓣和旁瓣。
如6所示，图6为本发明实施例提供的一种7.5MHz三维相控阵超声换能器在设定平面内的声场分布图，由图6可知，该三维相控阵超声换能器6在特定平面所有超声换能器阵元20的声场分布，可以看出，声场最大幅值出现在中心且对称分布。
需要注意的是，为了实现比较理想的重建效果，上述仿真用的三维相控阵超声换能器6在高度方向和径向方向使用了较多的超声换能器阵元20。在实际使用中，可以适当放宽对重建伪影的限制，以大幅度减小超声换能器阵元20数目。
在三维相控阵超声换能器6仿真的基础上，进行了光声成像仿真。仿真中，激光器1为光参量放大(OPO)激光器，输出波长范围为690-950nm和1200–2400nm，单脉冲的时间宽度约为6ns，重复频率10Hz。仿真中采用的数值仿体(即待成像物体4的仿真模型)为三维小球数值模型，包括8个直径为1.2mm的小球和1个直径为1.6mm的大球，如图7所示，图7为待成像物体的仿真模型图，该仿真模型为三维小球仿体模型。激光照射小球模型时，会激发出超声信号向三维空间传播。多通道数据采集电路10的通道个数为256，单通道最高采样速率为62.5MS/s，采集精度为14bit。图8为1.0微秒时刻三维小球周围产生的光声场空间分布图。图9为模拟三维相控阵超声换能器采集得到的光声信号分布图，图9中横轴为时间，纵轴为换能器的阵元个数。图10为利用反投影算法重建的三维小球图像。可以看出，利用本发明技术方案所述的光声成像系统，可以准确实现物体的三维成像。
基于上述光声成像系统，本发明另一实施例还提供了一种光声成像方法，可以通过上述实施例所述光声成像系统实现所述光声成像方法，具体的，所述光声成像方法包括：
步骤S11：通过激光器出射的激光脉冲照射待成像物体，通过热弹效应，激发待成像物体产生向三维空间传播的光声信号。
如上述可以采用高能脉冲激光器出射纳秒激光激发待成像物体，使得待成像物体中的吸收体吸收激光能量，瞬间产生温度升高，由于热弹效应，产生压力超声波信号(光声信号)，向三维空间传播。
步骤S12：通过三维相控阵超声换能器采集向三维空间传播的所述光声信号。
利用具有高密度多排超声换能器阵元20的三维相控阵超声换能器6接收在三维空间传播的光声信号，信号接收有激光器输出的同步信号触发。
步骤S13：通过多通道数据采集电路将所述三维相控阵超声换能器采集的所述光声信号进行信号处理。
该步骤中，对获取的多通道光声信号进行低噪声放大、滤波和高速并行模数转换后，传输至计算机进行光声成像。
步骤S14：通过计算机基于信号处理后的所述光声信号，形成所述待成像物体的三维光声图像。
通过计算机对离散的光声信号进行图像重建、图像处理和图像显示，恢复样品中吸收体的三维空间分布。
本发明实施例所述光声成像方法中，所述激光器出射的激光波长可以调节，可以在紫外、可见和近红外波段范围内，通过扫描激光波长，进行多光谱成像，基于光谱图像进行待成像物体的化学成分的无创表征，也就是通过对应波段激光扫描待成像物体，通过多通道数据采集电路对三维相控阵超声换能器采集的所述光声信号进行信号处理后，计算机还可以基于信号处理后的所述光声信号进行多光谱成像。
本发明实施例所述光声成像方法可以对所述三维相控阵超声换能器中多排超声换能器阵元接收到的超声信号在傅里叶域进行频谱分析，基于频谱分析 结果，对所述待成像物体的物理性质进行无创表征，通过所述计算机对三维相控阵超声换能器采集的所述光声信号进行频谱分析，可以实现待成像物体的物理性质的无创表征。
本发明实施例所述光声成像方法可以通过GPU加速方法，以提升所述光声成像系统中多通道信号和图像的处理速度。
本说明书中各个实施例采用递进、或并行、或递进和并行相结合的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。对于实施例公开的方法而言，由于其与实施例公开的系统相对应，所以描述的比较简单，相关之处参见系统部分说明即可。
还需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括上述要素的物品或者设备中还存在另外的相同要素。
对所公开的实施例的上述说明，使本领域专业技术人员能够实现或使用本发明。对这些实施例的多种修改对本领域的专业技术人员来说将是显而易见的，本文中所定义的一般原理可以在不脱离本发明的精神或范围的情况下，在其它实施例中实现。因此，本发明将不会被限制于本文所示的这些实施例，而是要符合与本文所公开的原理和新颖特点相一致的最宽的范围。

Claims (10)

  1. 一种光声成像系统，其特征在于，所述光声成像系统包括：
    激光器，所述激光器用于出射激光脉冲，以照射待成像物体，通过热弹效应，激发待成像物体产生向三维空间传播的光声信号；
    三维相控阵超声换能器，所述三维相控阵超声换能器用于采集向三维空间传播的所述光声信号；所述三维相控阵超声换能器具有柱状基底，所述柱状基底上固定有超声换能器阵列，所述超声换能器阵列包括多排环绕所述柱状基底中轴线的超声换能器阵元；所述轴线为所述柱状基底的顶面中点与底面中点连线；
    多通道数据采集电路，所述多通道数据采集电路用于将所述三维相控阵超声换能器采集的所述光声信号进行信号处理；
    计算机，所述计算机用于基于信号处理后的所述光声信号，形成所述待成像物体的三维光声图像。
  2. 根据权利要求1所述的光声成像系统，其特征在于，所述激光器产生的激光脉冲通过光纤照明系统照射所述待成像物体；
    其中，所述光纤照明系统包括：光纤耦合器以及多路光纤束；所述光纤束的一端通过所述光纤耦合器耦合至所述激光器的激光输出端口，多路所述光纤束的另一端均分布于同一圆周，所述圆周包围所述待成像物体，为所述待成像物体提供均匀照明。
  3. 根据权利要求1所述的光声成像系统，其特征在于，所述激光器产生的激光脉冲通过自由光路照明系统照射所述待成像物体；
    所述自由光路照明系统包括：漫射器、圆锥透镜以及聚光器，所述激光器产生的激光脉冲依次通过所述漫射器、所述圆锥透镜以及所述聚光器后，照射所述待成像物体。
  4. 根据权利要求1所述的光声成像系统，其特征在于，所述三维相控阵超声换能器包括多个超声换能器阵元；
    所述多通道数据采集电路包括：多通道放大器、多通道滤波器以及多通道模数转换器；每个所述超声换能器阵元单独对应一个通道，所述超声换能器阵元采集所述光声信号经过对应通道依次进行放大、滤波和模数转换处理后，发 送给所述计算机。
  5. 根据权利要求1所述的光声成像系统，其特征在于，所述多通道数据采集电路与所述三维相控阵超声换能器之间具有时分复用器，所述时分复用器用于多通道信号的分时采集。
  6. 根据权利要求1所述的光声成像系统，其特征在于，所述柱状基底具有贯穿其顶面和底面的通孔，所述超声换能器阵元均固定在所述通孔的内壁；
    或，所述超声换能器阵元均固定在所述柱状基底的外侧面。
  7. 根据权利要求1所述的光声成像系统，其特征在于，还包括：机械扫描装置，所述机械扫描装置用于带动所述待成像物体或是所述三维相控阵超声换能器沿所述轴线平动或是绕所述轴线转动。
  8. 根据权利要求1所述的光声成像系统，其特征在于，所述柱状基底包括多个可拆分的子柱状基底；所述子柱状基底上至少设置一排所述超声换能器阵元；
    或，所述子柱状基底上均设置一排所述超声换能器阵元，所述子柱状基底上所述超声换能器阵元的数量以及分布相同。
  9. 一种光声成像方法，其特征在于，所述光声成像方法包括：
    通过激光器出射的激光脉冲照射待成像物体，通过热弹效应，激发待成像物体产生向三维空间传播的光声信号；
    通过三维相控阵超声换能器采集向三维空间传播的所述光声信号；
    通过多通道数据采集电路将所述三维相控阵超声换能器采集的所述光声信号进行信号处理；
    通过计算机基于信号处理后的所述光声信号，形成所述待成像物体的三维光声图像。
  10. 根据权利要求9所述的光声成像方法，其特征在于，还包括：
    在紫外、可见光和红外波长范围内，通过扫描激光波长，进行多光谱成像，基于光谱图像进行所述待成像物体的化学成分的无创表征；
    或，对所述三维相控阵超声换能器中多排超声换能器阵元接收到的超声信 号在傅里叶域进行频谱分析，基于频谱分析结果，对所述待成像物体的物理性质进行无创表征；
    或，通过GPU加速方法，提升所采集的多路光声信号和图像的处理速度。
PCT/CN2020/110196 2019-08-23 2020-08-20 光声成像系统及方法 WO2021036897A1 (zh)

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Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110367942B (zh) * 2019-08-23 2021-03-09 中国科学技术大学 光声成像系统及方法
CN111035368B (zh) * 2020-01-07 2022-12-13 上海科技大学 单通道实时光声断层扫描成像系统与方法
CN113116296A (zh) * 2020-01-13 2021-07-16 香港城市大学深圳研究院 一种光声超声协同诊疗系统
WO2021237417A1 (zh) * 2020-05-25 2021-12-02 中国科学院深圳先进技术研究院 一种全景光随动装置及其光声成像系统
CN111772581B (zh) * 2020-06-11 2023-03-28 华南师范大学 基于双曲率线阵探测器的高灵敏度光声/超声双模式成像装置及方法
CN111948147B (zh) * 2020-09-25 2023-07-25 广东工业大学 一种无盲区的全场域超声显微镜成像系统及其方法
WO2022104701A1 (zh) * 2020-11-20 2022-05-27 深圳先进技术研究院 超声探头、内窥镜、内窥成像系统以及内窥成像方法
CN112505668B (zh) * 2020-12-01 2024-02-13 中国人民解放军海军工程大学 激光致声发射相控阵聚焦系统
CN112890856A (zh) * 2020-12-31 2021-06-04 江苏霆升科技有限公司 用于超声成像的二维超声换能器阵列、成像方法及装置
CN113545747B (zh) * 2021-06-01 2024-04-12 广东省科学院健康医学研究所 一种激光散斑-光声联合成像装置及其实现方法
CN113607652B (zh) * 2021-08-11 2022-06-24 电子科技大学 一种基于光声谱的工件浅表分层成像方法
CN114209282A (zh) * 2021-12-22 2022-03-22 复旦大学 一种超声和光声的多模态高分辨率三维扫描成像装置
CN114563479B (zh) * 2022-04-20 2022-08-30 之江实验室 一种实时三维高分辨太赫兹光声成像方法和装置
CN114964361B (zh) * 2022-04-26 2023-10-10 南京大学 一种基于das的海洋光声断层成像方法及系统
CN115040083B (zh) * 2022-06-24 2023-03-10 苏州芙迈蕾医疗科技有限公司 基于多超声换能器的光声层析和超声成像系统及方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130044563A1 (en) * 2011-08-08 2013-02-21 Canon Kabushiki Kaisha Object information acquisition apparatus, object information acquisition system, display control method, display method, and program
CN105249933A (zh) * 2015-11-20 2016-01-20 哈尔滨海鸿基业科技发展有限公司 光声分子三维成像仪
CN105266761A (zh) * 2014-07-24 2016-01-27 佳能株式会社 光声装置
CN205411151U (zh) * 2016-02-18 2016-08-03 湖南工业大学 一种基于阵列探测器的超快光声成像装置
CN106175691A (zh) * 2016-08-26 2016-12-07 凌斌 柔性基底mems器件曲面阵列光声成像系统
CN109171816A (zh) * 2018-09-05 2019-01-11 中北大学 一种用于检查乳腺的超声ct系统及其扫描方法
CN110367942A (zh) * 2019-08-23 2019-10-25 中国科学技术大学 光声成像系统及方法
CN110367943A (zh) * 2019-08-23 2019-10-25 中国科学技术大学 相控阵超声换能器和超声相控检测系统

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201233362Y (zh) * 2008-06-04 2009-05-06 江西农业大学 一种用于检测水果品质的多光谱成像装置
CN105395170B (zh) * 2015-12-15 2018-07-27 同济大学 一种光声超声双模态同步成像系统
CN106154251A (zh) * 2016-06-27 2016-11-23 中国科学院苏州生物医学工程技术研究所 超声波束合成方法、超声成像方法和超声弹性成像方法
US10760956B2 (en) * 2016-07-05 2020-09-01 Canon Kabushiki Kaisha Wavefront control apparatus, wavefront control method, information acquiring apparatus, and storage medium
CN107607473B (zh) * 2017-08-31 2020-05-19 华南师范大学 一种同时多点激发与匹配接收的光声三维成像装置及方法
CN108042110A (zh) * 2017-12-22 2018-05-18 深圳先进技术研究院 多模成像系统
CN109363645B (zh) * 2018-10-29 2021-04-13 中国科学院上海技术物理研究所 一种基于激光光声光谱的人体血管检测方法

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130044563A1 (en) * 2011-08-08 2013-02-21 Canon Kabushiki Kaisha Object information acquisition apparatus, object information acquisition system, display control method, display method, and program
CN105266761A (zh) * 2014-07-24 2016-01-27 佳能株式会社 光声装置
CN105249933A (zh) * 2015-11-20 2016-01-20 哈尔滨海鸿基业科技发展有限公司 光声分子三维成像仪
CN205411151U (zh) * 2016-02-18 2016-08-03 湖南工业大学 一种基于阵列探测器的超快光声成像装置
CN106175691A (zh) * 2016-08-26 2016-12-07 凌斌 柔性基底mems器件曲面阵列光声成像系统
CN109171816A (zh) * 2018-09-05 2019-01-11 中北大学 一种用于检查乳腺的超声ct系统及其扫描方法
CN110367942A (zh) * 2019-08-23 2019-10-25 中国科学技术大学 光声成像系统及方法
CN110367943A (zh) * 2019-08-23 2019-10-25 中国科学技术大学 相控阵超声换能器和超声相控检测系统

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