Photoacoustic imaging method and system for enhancing low-light absorption coefficient component recognition

Abstract

The invention discloses a photoacoustic imaging method and system for enhancing low-light absorption coefficient component recognition, and the method comprises the steps: irradiating a biological tissue through a pulse light source, generating a photoacoustic signal in the biological tissue, and collecting the photoacoustic signal as an initial photoacoustic signal; irradiating the biological tissue again by using the pulse light source under the same condition based on different temperatures of each component of the biological tissue under the ultrasonic heat effect to obtain a photoacoustic signal after temperature rise; performing difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal; and performing inversion imaging processing on the temperature difference photoacoustic signal in a time domain to obtain a photoacoustic imaging image. According to the invention, a bright background caused by a high light absorption coefficient in photoacoustic imaging can be inhibited, and imaging identification of a low light absorption coefficient component is further enhanced.

Description

Technical Field

[0001] The present disclosure relates to the field of photoacoustic imaging, and in particular to a photoacoustic imaging method and system for enhancing identification of low light absorption coefficient components. Background Art

[0002] Photoacoustic imaging technology based on the photoacoustic effect uses the light absorption sensitivity of biological tissues and the light absorption coefficient of each component of biological tissues as the main imaging contrast, which can achieve good imaging resolution similar to that of optical imaging. At the same time, this technology uses ultrasound as the imaging signal carrier, which can make up for the shortcoming of shallow imaging depth in traditional optical imaging and realize imaging and identification of deeper biological tissue targets. Therefore, photoacoustic imaging combines the advantages of both acoustic and optical imaging, and has become an emerging medical diagnostic technology in recent years, receiving increasing attention.

[0003] Using light absorption coefficient as imaging contrast improves the accuracy of medical diagnosis. However, the light absorption coefficients of some components in biological tissues vary greatly, making it difficult to identify components with weak light absorption coefficients in the imaging image. It is challenging to image and identify components with low light absorption coefficients under the "bright background" caused by the strong photoacoustic signal of the high light absorption coefficient components. The solutions to the above problems currently focus on utilizing the differences in the light absorption spectra of each component and improving the imaging quality through signal processing and imaging algorithms. Among them, photoacoustic imaging technology using multi-wavelength pulsed lasers can realize the imaging and identification of some non-vascular components, but it is still subject to the light absorption characteristics of each component of biological tissue, and it is still difficult to identify components with similar light absorption spectrum distribution laws. In terms of frequency domain analysis, the method of using the eigenfrequency of biological tissue viscoelasticity and combining it with an improved imaging algorithm for frequency domain analysis can locate some low light absorption coefficient components in the imaging image, but because a single frequency is used for imaging, the resolution is very limited. Summary of the invention

[0004] In order to effectively suppress the influence of the bright background caused by the high light absorption coefficient component on the imaging of the low light absorption coefficient component in photoacoustic imaging, the purpose of the present invention is to provide a photoacoustic imaging method and system for enhancing the identification of the low light absorption coefficient component, so as to realize the effective imaging identification of the low light absorption coefficient component. In order to achieve the above purpose, the present invention adopts the following scheme.

[0005] A photoacoustic imaging method for enhancing the identification of low light absorption coefficient components, characterized in that the method comprises the following steps:

[0006] Step S1: using a pulse light source to irradiate biological tissue to generate a photoacoustic signal in the biological tissue, and collecting the photoacoustic signal as an initial photoacoustic signal;

[0007] Step S2: Based on the different temperature rises of various components of the biological tissue due to the ultrasonic thermal effect, the biological tissue is irradiated again with a pulse light source under the same conditions as in step S1 to obtain a photoacoustic signal after the temperature rise;

[0008] Step S3: performing difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal;

[0009] Step S4: performing inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

[0010] Optionally, in step S1, an array ultrasonic transducer is used to collect the photoacoustic signal.

[0011] Optionally, the photoacoustic signal includes signals collected by all array elements of the arrayed ultrasonic transducer.

[0012] Optionally, in step S1, the pulse light source is a Gaussian beam pulse laser, and the wavelength range of the Gaussian beam pulse laser is 690-960 nm.

[0013] Optionally, in step S2, a power amplifier is used in combination with a planar non-focused power ultrasound probe to irradiate the biological tissue, causing different temperature rises in various components of the biological tissue.

[0014] Optionally, in step S3, the difference processing is performed in the following manner:

[0015] ΔPA i =PA2 i -PA1 i

[0016] Where, the subscript i, i = 1, 2, ..., n, i represents the specified transducer array element, n represents the number of array elements, PA1 i and PA2 i represent the initial photoacoustic signal and the photoacoustic signal after temperature rise, ΔPA i Represents the temperature difference photoacoustic signal.

[0017] Optionally, in step S4, the pixel value of the imaging point is calculated according to the following method:

[0018]

[0019] Where I(x,y) is the pixel value of the imaging point (x,y), N is the number of photoacoustic signals collected by the array transducer, and S n is the nth photoacoustic signal, r n (x, y) is the straight-line distance between the imaging point (x, y) and the nth transducer array element, and c is the sound velocity of the biological tissue being measured.

[0020] In addition, the present invention also discloses a photoacoustic imaging system for enhancing the identification of low light absorption coefficient components, the system comprising: a laser module, an ultrasonic thermal effect module, a signal processing module and an imaging module, wherein:

[0021] A laser module, which is used to generate a photoacoustic signal in the biological tissue by irradiating the biological tissue with a pulse light source, and collect the photoacoustic signal as an initial photoacoustic signal;

[0022] Ultrasonic thermal effect module, which is used to generate different temperature rises in various components of biological tissues based on ultrasonic thermal effect, and to irradiate the biological tissues again with a pulsed light source to obtain photoacoustic signals after the temperature rise;

[0023] A signal processing module, which is used to perform difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal;

[0024] The imaging module is used to perform inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

[0025] Optionally, the ultrasonic thermal effect module irradiates ultrasonic waves to biological tissues to cause ultrasonic thermal effect in the biological tissues, thereby causing different components of the biological tissues to generate different temperature rises due to differences in sound absorption coefficients.

[0026] The present invention has the following beneficial effects: The present invention discloses a photoacoustic imaging method and system for enhancing the identification of low light absorption coefficient components. While retaining the traditional photoacoustic imaging that relies on the light absorption characteristics of biological tissue components as the main factor of the photoacoustic effect, it introduces the temperature difference effect caused by the ultrasonic thermal effect caused by ultrasonic irradiation of biological tissues, which is affected by the sound absorption characteristics. By performing difference processing and imaging on the photoacoustic signals collected by irradiating the biological tissue with laser before and after the introduction of the temperature difference effect, the bright background caused by components such as blood in photoacoustic imaging can be suppressed, and the imaging identification of low light absorption coefficient components can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate exemplary embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0028] Figure 1 is a schematic diagram of an imaging system provided by an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the position of a biological tissue phantom to be tested provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic cross-sectional view of a biological tissue phantom to be tested provided by an embodiment of the present invention;

[0031] Figure 4 It is a photoacoustic imaging method and system flow chart of enhancing the identification of low light absorption coefficient components provided by an embodiment of the present invention;

[0032] Figure 5 is a reference photoacoustic signal of a biological tissue phantom collected by a certain array element of an array ultrasonic transducer obtained by the method provided in an embodiment of the present invention;

[0033] Figure 6 The photoacoustic signal after the temperature rise of the biological tissue phantom collected by the same array element of the array ultrasonic transducer obtained by the method provided in the embodiment of the present invention;

[0034] Figure 7 is a temperature difference photoacoustic signal of a biological tissue phantom obtained by the method provided in an embodiment of the present invention;

[0035] Figure 8 An imaging image obtained by a conventional photoacoustic imaging method provided by an embodiment of the present invention;

[0036] Fig. 9 It is a typical imaging image obtained by the method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The following is combined with Figures 1 to 9 The present disclosure is further described in detail with reference to the embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant contents, rather than to limit the present disclosure. It should also be noted that, for ease of description, only the parts related to the present disclosure are shown in the drawings.

[0038] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in the present disclosure can be combined with each other. The technical solution of the present disclosure will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0039] Unless otherwise specified, the exemplary embodiments / embodiments shown will be understood as providing exemplary features of various details of some ways in which the technical concept of the present disclosure can be implemented in practice. Therefore, unless otherwise specified, the features of the various embodiments / embodiments can be combined, separated, interchanged and / or rearranged without departing from the technical concept of the present disclosure.

[0040] The use of cross-hatching and / or shading in the accompanying drawings is generally used to make the boundaries between adjacent components clear. As such, unless otherwise specified, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement for the specific materials, material properties, dimensions, proportions, commonalities between the components shown, and / or any other characteristics, attributes, properties, etc. of the components. In addition, in the accompanying drawings, the sizes and relative sizes of the components may be exaggerated for clarity and / or descriptive purposes. When the exemplary embodiments can be implemented differently, the specific process sequence can be performed in a different order than described. For example, two successively described processes can be performed substantially simultaneously or in an order opposite to the described order. In addition, the same figure numbers represent the same components.

[0041] When a component is referred to as being "on" or "over," "connected to," or "coupled to" another component, the component may be directly on, directly connected to, or directly coupled to the other component, or intervening components may be present. However, when a component is referred to as being "directly on," "directly connected to," or "directly coupled to" another component, there are no intervening components. For this purpose, the term "connected" may refer to a physical connection, an electrical connection, etc., with or without intervening components.

[0042] For descriptive purposes, the present disclosure may use spatially relative terms such as "under," "beneath," "under," "down," "over," "upper," "above," "higher," and "side (e.g., as in "sidewall")," to describe the relationship of one component to another (other) component as shown in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, components described as "under" or "beneath" other components or features would subsequently be positioned "over" the other components or features. Thus, the exemplary term "under" can encompass both the "above" and "below" orientations. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0043] The terms used here are for the purpose of describing specific embodiments, and are not intended to be restrictive. As used here, unless the context clearly indicates otherwise, the singular forms "one (kind, person)" and "said (the)" are also intended to include plural forms. In addition, when the terms "comprise" and / or "include" and their variations are used in this specification, it is explained that there are stated features, integral bodies, steps, operations, parts, assemblies and / or their groups, but it is not excluded that there are or add one or more other features, integral bodies, steps, operations, parts, assemblies and / or their groups. It should also be noted that, as used here, the terms "substantially", "approximately" and other similar terms are used as approximate terms and not as degree terms, so that they are used to explain the inherent deviations of the measured values, calculated values ​​and / or the values ​​provided that will be recognized by those of ordinary skill in the art.

[0044] In one embodiment, the present invention provides a photoacoustic imaging method for enhancing identification of low light absorption coefficient components, characterized in that the method comprises the following steps:

[0045] Step S1: using a pulse light source to irradiate biological tissue to generate a photoacoustic signal in the biological tissue, and collecting the photoacoustic signal as an initial photoacoustic signal;

[0046] Step S2: Based on the different temperature rises of various components of the biological tissue due to the ultrasonic thermal effect, the biological tissue is irradiated again with a pulse light source under the same conditions as in step S1 to obtain a photoacoustic signal after the temperature rise;

[0047] Step S3: performing difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal;

[0048] Step S4: performing inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

[0049] In one embodiment, in step S1, an array ultrasonic transducer is used to collect the photoacoustic signal.

[0050] In one embodiment, the photoacoustic signal includes signals collected by all array elements of the arrayed ultrasonic transducer.

[0051] In one embodiment, in step S1, the pulse light source is a Gaussian beam pulse laser, and the wavelength range of the Gaussian beam pulse laser is 690-960 nm.

[0052] In one embodiment, in step S2, a power amplifier is used in combination with a planar non-focused power ultrasound probe to irradiate biological tissue, causing different temperature rises in various components of the biological tissue.

[0053] In one embodiment, in step S3, the difference processing is performed in the following manner:

[0054] ΔPA i =PA2 i -PA1 i

[0055] Where, the subscript i, i = 1, 2, ..., n, i represents the specified transducer array element, n represents the number of array elements, PA1 i and PA2 i represent the initial photoacoustic signal and the photoacoustic signal after temperature rise, ΔPA i Represents the temperature difference photoacoustic signal.

[0056] In one embodiment, in step S4, the pixel value of the imaging point is calculated as follows:

[0057]

[0058] Where I(x, y) is the pixel value of the imaging point (x, y), N is the number of photoacoustic signals collected by the array transducer, and S n is the nth photoacoustic signal, r n (x, y) is the straight-line distance between the imaging point (x, y) and the nth transducer array element, and c is the sound velocity of the biological tissue being measured.

[0059] In one embodiment, the present invention provides a photoacoustic imaging system for enhancing the identification of low light absorption coefficient components, the system comprising: a laser module, an ultrasonic thermal effect module, a signal processing module and an imaging module, wherein:

[0060] A laser module, which is used to generate a photoacoustic signal in the biological tissue by irradiating the biological tissue with a pulse light source, and collect the photoacoustic signal as an initial photoacoustic signal;

[0061] Ultrasonic thermal effect module, which is used to generate different temperature rises in various components of biological tissues based on ultrasonic thermal effect, and to irradiate the biological tissues again with a pulsed light source to obtain photoacoustic signals after the temperature rise;

[0062] A signal processing module, which is used to perform difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal;

[0063] The imaging module is used to perform inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

[0064] In one embodiment, the ultrasonic thermal effect module irradiates ultrasonic waves to biological tissues to cause ultrasonic thermal effects in the biological tissues, thereby causing different components of the biological tissues to generate different temperature rises due to differences in sound absorption coefficients.

[0065] refer to Figure 1 , a schematic diagram of a photoacoustic imaging system for enhancing the identification of low light absorption coefficient components provided by the present invention, the system comprises: a laser module, an ultrasonic thermal effect module, a signal acquisition module and an imaging processing module, wherein,

[0066] A laser module irradiates the biological tissue with laser of specified parameters;

[0067] The ultrasonic thermal effect module irradiates ultrasonic waves to biological tissues, causing ultrasonic thermal effects on biological tissues, which in turn causes different temperature rises in different components of biological tissues due to differences in sound absorption coefficients;

[0068] A signal acquisition module, which uses an array transducer to collect photoacoustic signals;

[0069] Imaging processing module: processes the collected signals and creates images.

[0070] refer to Figure 2 Schematic diagram of the position of the biological tissue phantom to be tested, in which 1 is a water tank, 2 is the biological tissue phantom to be tested, 3 and 4 are acoustic permeable membranes, the biological tissue is immersed in water, 5 and 6 in the figure represent the water content, and position D1 is a point on the upper surface of the biological tissue. The laser irradiates the upper surface of the biological tissue phantom to be tested at position D1. The laser irradiates point D1. In practice, the light spot has a size, so the point at position D1 is used as the geometric center point of the light spot. The linear array ultrasonic transducer is also immersed in water to collect photoacoustic signals at position D2. The vertical distance between D2 and D1 is 40 mm. The transducer of the power ultrasonic device is placed at position D3, which is 160 mm vertically away from the lower surface of the biological tissue phantom to be tested, and irradiates ultrasonic waves upward.

[0071] refer to Figure 3 , a schematic cross-sectional view of a biological tissue phantom to be tested provided by an embodiment of the present invention, wherein the matrix M of the phantom is made of a tissue phantom with material properties similar to fat, and has a size of 30×20×30 mm. The targets to be identified T1 and T3 are solid rods with a main component of calcium phosphate and a diameter of 2.5 mm, and the target to be identified T2 is a blood phantom filled with chicken blood and with a diameter of 2.5 mm. Figure 3 The coordinate origin is shown, and the coordinates of the three target positions to be identified are: T1 (5, 15), T2 (15, 10), and T3 (25, 12.5).

[0072] refer to Figure 4 The embodiment of the present invention provides a photoacoustic imaging method for enhancing the identification of low light absorption coefficient components, and the method comprises the following steps:

[0073] Step S1: using a pulse light source to irradiate biological tissue to generate a photoacoustic signal in the biological tissue, and collecting the photoacoustic signal as an initial photoacoustic signal;

[0074] Step S2: Based on the different temperature rises of various components of the biological tissue due to the ultrasonic thermal effect, the biological tissue is irradiated again with a pulse light source under the same conditions as in step S1 to obtain a photoacoustic signal after the temperature rise;

[0075] Step S3: performing difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal;

[0076] Step S4: performing inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

[0077] In one embodiment, in step S1 , a photoacoustic signal is collected by an arrayed ultrasonic transducer, and the photoacoustic signal includes a signal collected by each transducer array element.

[0078] In one embodiment, the pulse light source in step S1 is a pulse laser of a Gaussian beam, and a wavelength within the range of 690-960 nm is selected.

[0079] Considering that light absorbers such as hemoglobin in the blood have weak light absorption in the wavelength range of 690-960nm, while other biological tissue light absorbers have higher light absorption coefficients in this band, this wavelength range is more conducive to solving the imaging and identification problems of low light absorption components.

[0080] By comparing the light absorption coefficients of different biological tissue components, we can get a relative "high" and "low". For example, the light absorption coefficient of components such as hemoglobin is 100-1000 times higher than that of components such as fat and muscle, so it can be considered as a "high light absorption coefficient"; in contrast, other biological tissue components have a "low light absorption coefficient".

[0081] In one embodiment, the specific method of causing different temperature rises in various components of the biological tissue in step S2 is: using a power amplifier in combination with a planar non-focused power ultrasound probe to excite ultrasound to irradiate the biological tissue.

[0082] In one embodiment, a 690nm Gaussian beam pulse laser is selected, the power of the power amplifier used is 20W, the excited ultrasound is a 1MHz frequency sine continuous wave, and the working area of ​​the planar non-focused power ultrasound probe is 7cm 2 .

[0083] In one embodiment, a power amplifier is used in combination with a planar non-focused power ultrasound probe to excite ultrasound waves to irradiate biological tissue for a duration of 1.5 seconds. Considering the thermal diffusion of biological tissue, when the power ultrasound equipment stops working, a laser is immediately used to irradiate the biological tissue phantom and collect the photoacoustic signal after the temperature rise.

[0084] Due to the influence of biological heat diffusion, after continuous ultrasound irradiation for a period of time, the obvious temperature rise difference between different components in biological tissues will be affected by heat diffusion and gradually become blurred. In addition, considering the safety of biological tissues, the ultrasound irradiation time cannot be too long, so the temperature rise time needs to be controlled. Based on the power amplifier device provided in the embodiment, the ultrasound irradiation time that can produce obvious temperature rise differences should be controlled within the time range of 1-1.5s.

[0085] In one embodiment, the difference processing of the photoacoustic signal after temperature rise and the initial photoacoustic signal in step S3 is performed in the following manner:

[0086] ΔPA i =PA2 i -PA1 i

[0087] The subscript i (i = 1, 2, .., n) indicates the specified transducer array element, n indicates the number of array elements, PA1 i and PA2 i represent the initial photoacoustic signal and the photoacoustic signal after temperature rise, ΔPA i Represents the temperature difference photoacoustic signal.

[0088] In one embodiment, in step S4, the pixel value of the imaging point is calculated as follows:

[0089]

[0090] Where I(x,y) is the pixel value of the imaging point (x,y), N is the number of photoacoustic signals collected by the array transducer, and S n is the nth photoacoustic signal, r n (x, y) is the straight-line distance between the imaging point (x, y) and the nth transducer array element, and c is the sound velocity of the biological tissue being measured; in this embodiment, c=1540 m / s, and N=64.

[0091] Reference Figure 5 The method obtains the time domain waveform of the initial photoacoustic signal of the biological tissue phantom collected by a certain array element of the array ultrasonic transducer. In the figure, an obvious photoacoustic signal waveform and a mixed waveform composed of its tail wave and echo can be seen. This obvious signal is analyzed as the photoacoustic signal of the target T2 to be identified. At this time, the weak photoacoustic signals generated by T1 and T3 have been submerged because their light absorption coefficients are much smaller than T2.

[0092] Reference Figure 6, the photoacoustic signal of the biological tissue phantom after the temperature rise collected by a certain array element of the array ultrasonic transducer obtained by the method. As can be seen from the figure, although the biological tissue phantom to be tested has an ultrasonic thermal effect, the photoacoustic signal of T2 still covers the photoacoustic signals of T1 and T3, and the signals of T1 and T3 are still difficult to identify.

[0093] Reference Figure 7 , the temperature difference photoacoustic signal of the biological tissue phantom obtained by the method. As can be seen from the figure, after the difference processing, two obvious photoacoustic signal waveforms appear in the figure, namely the temperature difference photoacoustic signals of T1 and T3, while the position corresponding to the T2 signal waveform before, the signal at this time is already very weak. At this time, the photoacoustic signals of T1 and T3 with weak light absorption coefficients have been clearly identified.

[0094] Reference Figure 8 , the imaging image obtained by the traditional photoacoustic imaging method, the pixel value is normalized according to the maximum value and displayed in the range of -20 to 0dB. The darker the color bar on the right, the higher the pixel value and the stronger the photoacoustic signal. It can be seen that in the results obtained by the traditional photoacoustic imaging method, only T2 with a large light absorption coefficient can be clearly displayed. The pixel values ​​of T1 and T3 (the range marked by the black circle in the figure) are low and difficult to identify effectively.

[0095] Reference Fig. 9 , a typical imaging image obtained by the method of the present invention. Figure 8 and Fig. 9 The processing method is the same, and the pixel value is also normalized according to the maximum value and displayed in the range of -20 to 0dB. Figure 8 As Fig. 9 A comparison result, by comparing Figure 8 and Fig. 9 visible, Fig. 9 New recognition targets appeared on the left and right sides, namely Figure 8 The bright background caused by the strong photoacoustic signal generated by T2 with a high light absorption coefficient drowns out T1 and T3 with low light absorption coefficients. Therefore, the comparison results show that the method of the present invention has a better ability to identify components with low light absorption coefficients than the traditional photoacoustic imaging method.

[0096] The present invention discloses a photoacoustic imaging method and system for enhancing the identification of low light absorption coefficient components. While retaining the traditional photoacoustic imaging that relies on the light absorption characteristics of biological tissue components as the main factor of the photoacoustic effect, it introduces the temperature difference effect caused by the ultrasonic thermal effect caused by ultrasonic irradiation of biological tissues, which is affected by the sound absorption characteristics. By performing difference processing and imaging on the photoacoustic signals collected by irradiating the biological tissue with laser before and after the introduction of the temperature difference effect, the bright background caused by components such as blood in the photoacoustic imaging can be suppressed, and the imaging identification of low light absorption coefficient components can be further improved.

[0097] In the description of this specification, the description with reference to the terms "one embodiment / method", "some embodiments / methods", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments / methods or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments / methods or examples described in this specification and the features of the different embodiments / methods or examples, unless they are contradictory.

[0098] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0099] Those skilled in the art should understand that the above embodiments are only for the purpose of clearly illustrating the present disclosure, and are not intended to limit the scope of the present disclosure. For those skilled in the art, other changes or modifications may be made based on the above disclosure, and these changes or modifications are still within the scope of the present disclosure.

Claims

1. A photoacoustic imaging method for enhancing the identification of low light absorption coefficient components, characterized in that: The method comprises the following steps: Step S1: using a pulse light source to irradiate biological tissue to generate a photoacoustic signal in the biological tissue, and collecting the photoacoustic signal as an initial photoacoustic signal; Step S2: Based on the different temperature rises of various components of the biological tissue due to the ultrasonic thermal effect, the biological tissue is irradiated again with a pulse light source under the same conditions as in step S1 to obtain a photoacoustic signal after the temperature rise; Step S3: performing difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal; Step S4: performing inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

2. The method according to claim 1, characterized in that Preferably, in step S1, an array ultrasonic transducer is used to collect the photoacoustic signal.

3. The method according to claim 2, characterized in that The photoacoustic signal includes signals collected by all array elements of the array ultrasonic transducer.

4. The method according to claim 1, characterized in that In the step S1, the pulse light source is a Gaussian beam pulse laser.

5. The method according to claim 4, characterized in that The pulse laser wavelength range of the Gaussian beam is 690-960nm.

6. The method according to claim 1, characterized in that In step S2, a power amplifier is used in combination with a planar non-focused power ultrasound probe to irradiate biological tissue, causing different temperature rises in various components of the biological tissue.

7. The method according to claim 1, characterized in that In step S3, the difference processing is performed in the following manner: ΔPA i =PA2 i -PA1 i Where, the subscript i, i = 1, 2, ..., n, i represents the specified transducer array element, n represents the number of array elements, PA1 i and PA2 i represent the initial photoacoustic signal and the photoacoustic signal after temperature rise, ΔPA i Represents the temperature difference photoacoustic signal.

8. The method according to claim 1, characterized in that In step S4, the pixel value of the imaging point is calculated as follows: Where I(x,y) is the pixel value of the imaging point (x,y), N is the number of photoacoustic signals collected by the array transducer, and S n is the nth photoacoustic signal, r n (x, y) is the straight-line distance between the imaging point (x, y) and the nth transducer array element, and c is the sound velocity of the biological tissue being measured.

9. A photoacoustic imaging system for enhancing identification of low light absorption coefficient components, characterized in that: The system includes: a laser module, an ultrasonic thermal effect module, a signal processing module and an imaging module, wherein: A laser module, which is used to generate a photoacoustic signal in the biological tissue by irradiating the biological tissue with a pulse light source, and collect the photoacoustic signal as an initial photoacoustic signal; Ultrasonic thermal effect module, which is used to generate different temperature rises in various components of biological tissues based on ultrasonic thermal effect, and to irradiate the biological tissues again with a pulsed light source to obtain photoacoustic signals after the temperature rise; A signal processing module, which is used to perform difference processing on the photoacoustic signal after temperature rise and the initial photoacoustic signal to obtain a temperature difference photoacoustic signal; The imaging module is used to perform inversion imaging processing on the temperature difference photoacoustic signal in the time domain to obtain a photoacoustic imaging image.

10. The system according to claim 9, characterized in that The ultrasonic thermal effect module irradiates ultrasonic waves to biological tissues, causing ultrasonic thermal effects to occur in the biological tissues, thereby causing different components of the biological tissues to have different temperature rises due to different sound absorption coefficients.

Images