CN112683807A - Tissue slice imaging method and imaging system - Google Patents
Tissue slice imaging method and imaging system Download PDFInfo
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- CN112683807A CN112683807A CN202011438429.0A CN202011438429A CN112683807A CN 112683807 A CN112683807 A CN 112683807A CN 202011438429 A CN202011438429 A CN 202011438429A CN 112683807 A CN112683807 A CN 112683807A
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Abstract
The invention discloses a tissue slice imaging method and an imaging system, wherein the method comprises the steps of transmitting a first pulse laser scanning signal to a tissue slice to be detected, wherein the first pulse laser scanning signal is used for heating the tissue slice; after the interval of the first time, transmitting a second pulse laser scanning signal to the tissue slice; receiving a photoacoustic signal excited by the second pulsed laser scanning signal from the tissue section; determining a photoacoustic image of the tissue slice from the photoacoustic signals. The method and the device utilize the dual-waveband excited photoacoustic microscopic imaging technology in the imaging of the tissue slice, thereby obtaining unmarked tissue slice imaging with high resolution and high contrast and being widely applied to the detection field.
Description
Technical Field
The invention relates to the field of detection, in particular to a tissue slice imaging method and a tissue slice imaging system.
Background
At present, biological tissues such as tumors and the like are mainly detected according to biopsy results, namely the biological tissues are taken out and sent to a pathology department for section staining to finally confirm the characteristics of the biological tissues. Although the result of the characteristic confirmation of the biological tissue by staining is more accurate, the process is generally slower, for some biological tissues, the operation needs to be performed on the patient for taking materials by one biopsy, and after the confirmation of the staining result, the secondary operation is performed according to the confirmation result, so that the pain of the patient is increased. In addition, the use amount of the dye and the dyeing level of an operator can influence the imaging result in the dyeing process, so that the imaging effect is influenced.
Photoacoustic imaging has a high resolution and, due to the specific absorption of tissue, histologically similar image results can be obtained without labeling the tissue. Therefore, through the photoacoustic imaging technology, the tissue slice can be subjected to rapid high-resolution high-contrast label-free imaging after the material is taken out in the operation, the state of the tissue slice is judged through the photoacoustic image, and the bedside rapid detection in the operation is realized. After the detection result is confirmed, the operation can be immediately carried out, so that the pain of the patient in the secondary operation is avoided.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a tissue slice imaging method and an imaging system, which can be used for carrying out unmarked high-resolution high-contrast slice imaging by using a photoacoustic imaging technology and rapidly and accurately judging the actual state of a slice tissue by obtaining a high-resolution high-contrast photoacoustic image with similar histology.
A tissue slice imaging method according to an embodiment of the first aspect of the invention comprises:
the method comprises the following steps that a first pulse laser emits a first pulse laser scanning signal to a tissue slice to be detected, and the first pulse laser scanning signal is used for heating the tissue slice;
after the interval of the first time, a second pulse laser emits a second pulse laser scanning signal to the tissue slice, and the second pulse laser scanning signal is used for exciting the photoacoustic signal of the tissue slice;
receiving a photoacoustic signal excited by the second pulsed laser scanning signal from the tissue section;
determining a photoacoustic image of the tissue slice from the photoacoustic signals.
The imaging method provided by the embodiment of the invention has at least the following beneficial effects: according to the embodiment of the invention, the tissue slice is heated in advance through the first pulse laser scanning signal, then the tissue slice is excited to send out the photoacoustic signal through the second pulse laser scanning signal, and the photoacoustic image of the tissue slice is determined according to the photoacoustic signal. The photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited tissue, and the higher the temperature is, the stronger the photoacoustic signal obtained by excitation is; therefore, the temperature of the tissue slice is increased through the first pulse laser scanning signal, and then the tissue slice is excited through the second pulse laser scanning signal, so that the high-resolution and high-contrast tissue slice imaging result can be obtained. Meanwhile, the photoacoustic imaging is label-free imaging, and can avoid the influence of dye on the imaging of the tissue slice.
A tissue slice imaging system according to another aspect embodiment of the invention comprises:
a first pulse laser for emitting a first pulse laser signal;
the second pulse laser is used for transmitting a second pulse laser signal;
the beam shaping module is used for receiving the second pulse laser signal, shaping the second pulse laser signal and outputting the second pulse laser signal;
the beam combiner is used for receiving the first pulse laser signal and transmitting and outputting the first pulse laser signal; the second pulse laser device is used for receiving the shaped second pulse laser signal and outputting the second pulse laser signal in a reflection mode;
the scanning module is used for receiving a first pulse laser signal output by the beam combiner and outputting a first pulse laser scanning signal, and receiving a second pulse laser signal output by the beam combiner and outputting a second pulse laser scanning signal;
the displacement platform is used for placing the tissue slices to be detected;
a photoacoustic acquisition module for detecting a photoacoustic signal excited by the second pulsed laser scanning signal of the tissue slice;
a photoacoustic imaging module for determining a photoacoustic image of the tissue slice from the photoacoustic signal;
wherein the first pulsed laser scanning signal is used to heat the tissue slice.
The imaging system provided by the embodiment of the invention has at least the following beneficial effects: the embodiment of the invention comprises a first pulse laser and a second pulse laser, wherein a first pulse laser signal emitted by the first pulse laser passes through a scanning module to obtain a first pulse laser scanning signal, and a second pulse laser signal emitted by the second pulse laser passes through the scanning module to obtain a second pulse laser scanning signal; the first pulse laser scanning signal is used for heating the tissue slice, and the second pulse laser scanning signal is used for exciting the tissue slice to generate a photoacoustic signal. The photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited tissue, and the higher the temperature is, the stronger the photoacoustic signal obtained by excitation is; therefore, the temperature of the tissue slice is increased through the first pulse laser scanning signal, and then the tissue slice is excited through the second pulse laser scanning signal, so that the high-resolution and high-contrast tissue slice imaging result can be obtained. Meanwhile, the photoacoustic imaging is label-free imaging, and can avoid the influence of dye on the imaging of the tissue slice.
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The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic flow chart of an imaging method according to an embodiment of the present invention;
FIG. 2 is an exemplary flow diagram of an imaging method of an embodiment of the invention;
FIG. 3 is a schematic view of an imaging system according to an embodiment of the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
Before further detailed description of the embodiments of the present application, terms and expressions referred to in the embodiments of the present application are explained, and the terms and expressions referred to in the embodiments of the present application are applicable to the following explanations:
photoacoustic imaging (PAI) is a biological imaging technique based on the difference in light absorption and using photoacoustic waves (i.e., ultrasound) as information carriers. When biological tissues are irradiated by short pulse laser, the tissue absorbs light energy and generates heat, so that the temperature of a laser irradiation point changes to be instantaneously thermally expanded, and ultrasonic waves are radiated outwards. The phenomenon that light is excited to generate ultrasound is photoacoustic effect, the generated ultrasound signal is photoacoustic signal, and after the photoacoustic signal is received by an ultrasound detector, the light absorption distribution in the tissue is reconstructed by an algorithm, namely photoacoustic imaging. Photoacoustic imaging is a non-invasive imaging technique that is non-destructive. When the pulse laser excites the biological tissue, the ultrasonic wave is generated as an information carrier, and the optical absorption distribution image of the biological tissue is reconstructed by receiving the ultrasonic wave signal, so that the method is a non-ionization and non-invasive non-destructive imaging means.
Photoacoustic microscopy (PAM) is a commonly used mode of photoacoustic imaging. Similar to the working principle of an optical microscope, the photoacoustic microscope focuses pulse laser on the surface of an object to be measured through an objective lens so as to excite and generate photoacoustic signals, and meanwhile, a focused ultrasonic transducer is used for detecting the generated photoacoustic signals. Similar to the optical confocal microscope, in the photoacoustic microscope, the focus of the lens for focusing laser light and the focus of the focused ultrasound transducer for receiving are generally designed to be at the same position, so that the photoacoustic signal at the excitation point can be obtained with high sensitivity, and the photoacoustic imaging quality can be improved. The beam is weakly focused into the tissue and the ultrasound transducer is focused coaxially into the same region for confocal excitation and detection. The distance between the light excitation point and the receiving point can be calculated according to the time of receiving the photoacoustic signal, that is, a one-dimensional photoacoustic image can be reconstructed by a single-excited photoacoustic signal, that is, depth information in the Z-axis direction can be obtained by one-time point scanning. A two-dimensional photoacoustic image can be obtained by moving the tissue in the X-axis direction or the Y-axis direction.
Thermal relaxation time: when the target tissue absorbs the laser energy, the temperature must rise and heat must be conducted to the surrounding adjacent tissue. The process of conducting heat generated by the heat of the target object to the surrounding tissues is thermal relaxation, and the speed of measuring the thermal relaxation speed is the thermal relaxation time; the thermal relaxation time is the time required for the microscopic target to cool significantly (half the temperature drop). The thermal relaxation time formula is expressed as: tr is d2/(4k), where tr is the thermal relaxation time, d is the penetration depth of the laser, and k is the thermal dispersion.
At present, the main mode for imaging the tissue section in the operation is realized by staining and photographing, wherein the relevant biological tissue is taken out in the operation and sent to a pathology department for section staining and then photographing, and finally the characteristics of the biological tissue are confirmed through a stained tissue section picture. Although the result of biological tissue imaging by staining is accurate, the amount of dye used and the level of the operator in the staining process may affect the staining result, and the process is usually slow, and for some biological tissues on abdominal organs, the staining period for one biopsy is long. The patient may have to wait several days to obtain the results and may therefore be at risk for a second incision. Meanwhile, the photoacoustic imaging has high resolution and high imaging speed, and high-resolution slice image results similar to histology can be quickly obtained through specific wavelength due to specific absorption of biological tissues. Through the photoacoustic imaging technology, the tissue slice can be subjected to rapid high-resolution high-contrast label-free imaging after the material is taken out in the operation, and the bedside rapid imaging and detection in the operation are realized.
The embodiment of the invention provides a tissue slice imaging method and a tissue slice imaging system for realizing unmarked rapid high-resolution high-contrast by utilizing a photoacoustic imaging technology.
As shown in fig. 1, the tissue slice imaging method according to the embodiment of the present invention includes the following steps:
s110, a first pulse laser emits a first pulse laser scanning signal to a tissue slice to be detected, wherein the first pulse laser scanning signal is used for heating the tissue slice;
s120, after the interval of the first time, a second pulse laser emits a second pulse laser scanning signal to the tissue slice, and the second pulse laser scanning signal is used for exciting the photoacoustic signal of the tissue slice;
s130, receiving a photoacoustic signal excited by the second pulse laser scanning signal of the tissue slice;
and S140, determining a photoacoustic image of the tissue slice according to the photoacoustic signal.
The photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited biological tissue, and the higher the temperature is, the stronger the photoacoustic signal obtained by excitation is. According to the embodiment of the invention, the tissue slice is heated in advance through the first pulse laser scanning signal, then the tissue slice is excited to send out the photoacoustic signal through the second pulse laser scanning signal, and the photoacoustic image of the tissue slice is determined according to the photoacoustic signal. The photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited tissue, and the higher the temperature is, the stronger the photoacoustic signal obtained by excitation is; therefore, the temperature of the tissue slice is increased through the first pulse laser scanning signal, and then the tissue slice is excited through the second pulse laser scanning signal, so that the high-resolution and high-contrast tissue slice imaging result can be obtained.
Optionally, the first pulsed laser scanning signal is a pulsed laser scanning signal in a near-infrared band.
In the near infrared wavelength photoacoustic microscopic imaging technology, information of relative depth can be obtained due to wavelength, but laser in the wavelength band is difficult to focus to be small enough, high-resolution results cannot be obtained for section imaging, and meanwhile, the absorption of water in the wavelength band is large and is not beneficial to specific imaging of target tissues. Biological tissues are composed of a plurality of components, while water is generally the most abundant component, but water is not the target component to be observed when observing tissue slice images, that is, absorption of water can interfere with observation of target tissues. The absorption of water is gradually increased along with the increase of the wavelength, the absorption peak value of the water is far larger than the absorption of other components such as fat, cholesterol, protein, collagen fibers and the like, and meanwhile, when the near infrared light is used for excitation, most laser energy absorbed by the water in the biological tissue is unfavorable for excitation of the other components in the biological tissue, namely, if the interference of the photoacoustic image water obtained by using the near infrared light for excitation is too large, the specific imaging of a target substance is unfavorable. As described above, the photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited biological tissue, and the higher the temperature is, the stronger the photoacoustic signal obtained by excitation is. Therefore, in the present embodiment, the tissue slice is irradiated with the highly-absorbed near-infrared light to increase the temperature thereof, and then excited by the second pulse laser signal, so as to obtain the high-resolution and high-contrast tissue slice imaging result.
Optionally, the wavelength range of the first pulsed laser scanning signal is 780nm to 2526 nm. The wavelength of the first pulsed laser scanning signal may be 780nm, 1000nm, or 2526nm, or other wavelengths in the range of 780nm to 2526 nm. After the laser with the wavelength within the range irradiates the biological tissue, the temperature of the biological tissue is increased, so that the biological tissue can obtain a high-resolution and high-contrast tissue slice imaging result when the biological tissue is excited by the second pulse laser scanning signal.
Optionally, the second pulsed laser scanning signal is a pulsed laser scanning signal in an ultraviolet band.
The photoacoustic imaging in the ultraviolet band can obtain a high-resolution photoacoustic image, but the signal-to-noise ratio of the obtained photoacoustic signal is low because biological tissues absorb the ultraviolet band weakly, which is not favorable for obtaining a high-contrast photoacoustic image. But the tissue section imaging result with high resolution and high contrast can be obtained by irradiating the tissue with the first pulse laser scanning signal with high absorption to increase the temperature of the tissue and then exciting the tissue by the ultraviolet pulse laser. Namely, the tissue slice imaging result with high resolution and high contrast is realized through the matching of two pulse laser signals.
Optionally, the wavelength range of the second pulsed laser scanning signal is 400nm or less. The wavelength of the second pulsed laser scanning signal may be 192nm, 300nm or 355nm, or other wavelengths in the range of 400 nm. The wavelength range of the second pulse laser scanning signal can also be between 192nm and 355 nm. The laser of the wave band can be focused to be small enough, which is beneficial to obtaining the tissue slice imaging result with high resolution and high contrast when the biological tissue is excited by the second pulse laser scanning signal.
Optionally, the first time is determined from a thermal relaxation time of the tissue section, a repetition rate of the first pulsed laser scan signal and a repetition rate of the second pulsed laser scan signal.
The repetition frequency of the pulse laser signal is the emission frequency of the pulse laser signal. The first pulse laser scanning signal firstly irradiates the tissue slice, and the second pulse laser scanning signal is used for irradiating the tissue slice after the interval of the first time. The first time is required to be less than the thermal relaxation time of the tissue slice, the tissue slice absorbs the energy of the first pulse laser signal and then converts the energy into heat, but the heat cannot diffuse outwards in the set first time, so that the tissue slice is still under the heating effect of the first pulse laser signal when the second pulse laser signal arrives, and the strength of the photoacoustic signal excited by the second pulse laser signal is increased. The sum of the first time, the pulse width time of the first pulse laser signal and the pulse width time of the second pulse laser signal is smaller than the interval of two laser pulses of the first pulse laser signal, so that the heating effect of the first pulse laser signal can be realized each time, and the collection of the photoacoustic signals excited by the second pulse laser signal can be correctly collected without mutual interference. In this embodiment, the repetition frequency of the pulsed laser scanning signal is the repetition frequency of the pulsed laser signal, and both are the same.
Optionally, the first time is in a range of 5-10 microseconds, such as 5 microseconds, 6 microseconds, 8 microseconds, 9 microseconds, or 10 microseconds. Specifically, the setting may be determined based on the relationship between the first time and the thermal relaxation time, the repetition frequency of the first pulsed laser scanning signal, and the repetition frequency of the second pulsed laser scanning signal in this range.
Optionally, the imaging method further comprises:
a first pulsed laser signal is emitted and,
the first pulse laser signal passes through the beam combiner and then passes through the scanning module to obtain a first pulse laser scanning signal;
a second pulsed laser signal is emitted and,
and after the second pulse laser signal is subjected to beam shaping, the second pulse laser signal is reflected by the beam combiner and is sent to the scanning module to obtain a second pulse laser scanning signal.
The first pulse laser signal is transmitted by the beam combiner and then passes through the scanning module to obtain a first pulse laser scanning signal; the second pulse laser signal passes through the beam combiner for beam shaping output value, is reflected by the beam combiner and then passes through the scanning module to obtain a second pulse laser scanning signal, and the optical path behind the beam combiner is the same as the optical path behind the beam combiner of the first pulse laser signal. The two laser signals of the first pulse laser signal and the second pulse laser signal are combined by the beam combiner, and the optical paths behind the beam combiner are the same and can be effectively irradiated on the tissue section.
Optionally, a galvanometer in the scanning module is used for scanning the tissue slice in a smaller range, and a displacement platform on which the tissue slice is placed is used for moving the tissue slice in a larger range.
After the pulse laser signal reflected or transmitted by the beam combiner enters the scanning module, the pulse laser scanning signal from the scanning module is focused and then irradiates on the tissue slice on the displacement platform. The scanning module comprises a galvanometer, and the small-range scanning of the tissue slice is realized through the swinging of the galvanometer. After the small-range scanning is completed, the displacement platform can be moved, so that the position of the tissue slice is moved, and then the tissue slice is scanned in another small range by the swinging of the galvanometer. This is performed a plurality of times, and a scan of the tissue slice can be achieved. The smaller range refers to a smaller scanning range which can be involved by oscillating mirror relative to the scanning range which can be completed by moving the displacement platform; similarly, a larger range refers to a larger scanning range that can be achieved by the motion of the translation stage relative to the scanning range that can be achieved by the oscillating mirror. The first pulsed laser scanning signal and the second pulsed laser scanning signal can both scan the tissue slice by the method.
Optionally, the motion parameter of the galvanometer and the motion parameter of the displacement platform are determined according to the repetition frequency of the second pulse laser signal.
Parameters related to the movement of the galvanometer, such as the swing speed, the frequency or the interval of the galvanometer, limit the scanning range, the scanning speed and other scanning attributes of the scanning module for realizing small-range scanning through the galvanometer. The motion parameters related to the movement, such as the moving speed, the frequency or the interval of the displacement platform, limit the scanning attributes, such as the scanning range and the scanning speed.
Because the moving range of the galvanometer is relatively small and can be within a range of hundreds of micrometers, but a tissue slice is usually relatively large, the galvanometer can be used for scanning a small-range area, and then the displacement platform is used for moving a tissue slice sample to another position for photoacoustic scanning. For example, the movements of the galvanometer and the displacement platform are controlled by a program according to relevant parameters, and the specific control mode and the main body are not limited herein. The scanning of the galvanometer and the movement of the displacement platform are related to the repetition frequency of the second pulse laser signal. For example, a point-by-point scanning mode is adopted, so that the scanning speed of the galvanometer and the movement speed of the displacement platform are related to the repetition frequency and the scanning range of the first and second pulse laser signals. The specific orientation during scanning can be set according to the size of the target range and the characteristics of laser signals, photoacoustic signals and the like in a comprehensive consideration mode.
As shown in fig. 2, a detailed description of the imaging method is provided with reference to fig. 2 as a specific example of the embodiment of the present application.
S210, emitting a pulse laser signal in a near-infrared band;
and S220, after the first time interval, emitting a pulse laser signal in an ultraviolet band.
Due to the wavelength, the photoacoustic microscopic imaging of the near infrared wavelength can obtain information of a relative depth, but the laser of the wavelength band is difficult to focus to be small enough, a high-resolution result cannot be obtained for section imaging, and the absorption of water of the wavelength band is greatly unfavorable for specific imaging of target tissues. Laser light in an ultraviolet band can be focused to be small enough, so that photoacoustic imaging in the ultraviolet band can obtain a photoacoustic image with high resolution, but the signal-to-noise ratio of photoacoustic signals obtained due to weak absorption of tissues in the ultraviolet band is not good for obtaining a photoacoustic image with high contrast. The photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited tissue, and the higher the temperature is, the higher the photoacoustic signal obtained by excitation is. Therefore, the temperature of the tissue is raised by irradiating the tissue with high-absorption near infrared light, and then the tissue is excited by ultraviolet pulse laser, so that the unmarked high-resolution high-contrast tissue section imaging result can be obtained.
Irradiating the tissue by using a near-infrared band pulse laser signal, and heating the tissue; and irradiating the sliced tissues by using pulse laser signals in an ultraviolet band at intervals of the first time. The first time, such as 5-10 microseconds, is less than the thermal relaxation time of the tissue, and the specific setting of the first time can be determined according to the repetition frequency of emitting the two laser signals.
Wherein, the wavelength range of the pulse laser in the near infrared band is 780nm to 2526nm, including but not limited to the above wavelength range; the wavelength of the ultraviolet band pulse laser is below 400nm, such as 192nm to 355nm, including but not limited to the above wavelength range.
S230, transmitting the pulse laser signal of the near-infrared band through a beam combiner, and irradiating the tissue slice through a scanning module;
and S240, shaping the pulse laser signal of the ultraviolet band by a light beam, outputting the shaped pulse laser signal to a beam combiner, reflecting the shaped pulse laser signal by the beam combiner, outputting the shaped pulse laser signal to a scanning module, and irradiating the tissue slice by the scanning module.
The pulse laser signals of the near-infrared band are transmitted by the beam combiner and then irradiate the tissue slice by the scanning module; the laser signal of the ultraviolet wave band is shaped by a light beam, reflected by the beam combiner and irradiated to the tissue slice by the scanning module, and the light path behind the beam combiner is the same as that of the laser signal of the near-infrared wave band behind the beam combiner. The two laser signals are combined by the beam combiner, and the optical paths behind the beam combiner are the same and can be accurately irradiated on the tissue slice.
The scanning module comprises a two-dimensional galvanometer, and the small-range scanning of the tissue slice is realized through the swinging of the two-dimensional galvanometer. After the small-range scanning is completed, the displacement platform can be moved, so that the position of the tissue slice is moved, and then the tissue slice is scanned in another small range by the swinging of the galvanometer. After the small-range scan is completed, the displacement platform is moved to move the position of the tissue slice, … … is executed for multiple times, so that the target range of the tissue slice can be scanned. The small range refers to a small scanning range which can be related to the oscillating mirror swing relative to the scanning range which can be completed by the movement of the displacement platform; similarly, the large range refers to a large scanning range that can be achieved by moving the translation stage relative to the scanning range that can be achieved by oscillating the galvanometer. The first pulsed laser scanning signal and the second pulsed laser scanning signal can both scan the tissue slice by the method. Because the moving range of the two-dimensional galvanometer is smaller and may be within a range of hundreds of micrometers, but a tissue slice is usually larger, the two-dimensional galvanometer can firstly scan a small-range area by using the galvanometer, and then a tissue slice sample is moved to another position by using the displacement platform to perform photoacoustic scanning. The scanning of the galvanometer and the movement of the displacement platform are related to the repetition frequency of the pulse laser signal in the ultraviolet band. For example, in a point-by-point scanning manner, the speed of the scanning of the galvanometer and the movement of the displacement platform is related to the repetition frequency and the scanning range of the pulse laser signal in the near infrared band or the ultraviolet band. The scanning speed of the galvanometer determines the time required for completing the scanning of the small-range area, and whether the displacement platform moves depends on whether the scanning in the small range is completed or not, namely the scanning speed of the galvanometer is restricted. The distance of movement of the displacement platform needs to match the size of the area of the small area. That is, the scanning of the galvanometer and the movement of the displacement platform are both related to the repetition frequency of the pulse signal in the near infrared band or the ultraviolet band.
The specific orientation during scanning can be set according to the size of the target range and the characteristics of laser signals, photoacoustic signals and the like in a comprehensive consideration mode.
S250, collecting photoacoustic signals of the tissue slices excited by pulse laser signals in ultraviolet wave bands;
and S260, determining a photoacoustic image of the tissue slice according to the photoacoustic signal.
The tissue slice imaging system provided by the embodiment of the invention comprises:
a first pulse laser for emitting a first pulse laser signal;
the second pulse laser is used for transmitting a second pulse laser signal;
the beam shaping module is used for receiving the second pulse laser signal, shaping the second pulse laser signal and outputting the second pulse laser signal;
the beam combiner is used for receiving the first pulse laser signal and transmitting and outputting the first pulse laser signal; the second pulse laser device is used for receiving the shaped second pulse laser signal and outputting the second pulse laser signal in a reflection mode;
the scanning module is used for receiving a first pulse laser signal output by the beam combiner and outputting a first pulse laser scanning signal, and receiving a second pulse laser signal output by the beam combiner and outputting a second pulse laser scanning signal;
the displacement platform is used for placing the tissue slices to be detected;
a photoacoustic acquisition module for detecting a photoacoustic signal excited by the second pulsed laser scanning signal of the tissue slice;
a photoacoustic imaging module for determining a photoacoustic image of the tissue slice from the photoacoustic signal;
wherein the first pulsed laser scanning signal is used to heat the tissue slice.
The embodiment of the invention comprises a first pulse laser and a second pulse laser, wherein a first pulse laser signal emitted by the first pulse laser passes through a scanning module to obtain a first pulse laser scanning signal, and a second pulse laser signal emitted by the second pulse laser passes through the scanning module to obtain a second pulse laser scanning signal; the first pulse laser scanning signal is used for heating the tissue slice, and the second pulse laser scanning signal is used for exciting the tissue slice to generate a photoacoustic signal. The photoacoustic signal obtained by excitation in photoacoustic imaging is related to the temperature of the excited tissue, and the higher the temperature is, the stronger the photoacoustic signal obtained by excitation is; therefore, the temperature of the tissue slice is increased through the first pulse laser scanning signal, and then the tissue slice is excited through the second pulse laser scanning signal, so that the high-resolution and high-contrast tissue slice imaging result can be obtained.
Optionally, the first pulsed laser scanning signal is a pulsed laser scanning signal in a near-infrared band; the second pulse laser scanning signal is a pulse laser scanning signal of an ultraviolet band.
Optionally, the second pulse laser emits the second pulse laser signal after a first time after the first pulse laser emits the first pulse laser signal; the first time is determined based on a thermal relaxation time of the tissue slice, a repetition rate of the first pulsed laser scan signal, and a repetition rate of the second pulsed laser scan signal.
Optionally, a small-range scan of the tissue slice is achieved by the scanning module; and realizing large-range scanning of the tissue section by the movement of the displacement platform.
Optionally, the motion parameter of the scanning module and the motion parameter of the displacement platform are determined according to the repetition frequency of the second pulsed laser signal.
The function and the beneficial effect of the corresponding features in this embodiment are the same as those in the imaging method, and are not described herein again.
Fig. 3 shows a specific example of an imaging system of a tissue slice, in which a dotted line indicates an optical signal transmission path and a solid line indicates an electrical signal transmission path. As shown in fig. 3, the imaging system includes: a first pulse laser 301, a second pulse laser 302, a beam shaping module 303, a first mirror 304, a beam combiner 305, a second mirror 306, a scanning module 307, an objective lens 308, an ultrasonic transducer 312, a signal amplifier 313, a sampling module 314, and an image reconstruction module 315. The imaging system further includes a translation stage for positioning a stage 309 as shown in fig. 3, the stage 309 having a tissue section positioned thereon, the stage 309 being positioned within the coupling box 310. The ultrasonic transducer 312 is provided with an acoustic lens 311, which forms a photoacoustic acquisition module, and the photoacoustic acquisition module acquires an electrical signal according to a photoacoustic signal; the signal amplifier 313, the sampling module 314, and the image reconstruction module 315 constitute a photoacoustic imaging module, and the photoacoustic imaging module receives the electrical signal from the photoacoustic acquisition module, amplifies and/or performs analog-to-digital conversion on the electrical signal, and then obtains a photoacoustic image of the tissue slice by using the image reconstruction module. Certainly, the four modules of the acoustic lens 311, the ultrasonic transducer 312, the signal amplifier 313 and the sampling module 314 may also be named as a photoacoustic acquisition module, the image reconstruction module 315 serves as a photoacoustic imaging module, and the photoacoustic acquisition module obtains an electrical signal after being processed by the method and analog-to-digital conversion; or the three modules of the acoustic lens 311, the ultrasonic transducer 312 and the signal amplifier 313 are named as photoacoustic acquisition modules, and the acquisition module 314 and the image reconstruction module 315 are taken as photoacoustic imaging modules. As will be understood by those skilled in the art, the photoacoustic acquisition module is connected to the photoacoustic imaging module, the photoacoustic acquisition module is configured to convert a photoacoustic signal into an electrical signal, and the photoacoustic imaging module is configured to reconstruct a photoacoustic image according to the electrical signal, so that the related processing and acquisition parts of the electrical signal can be flexibly classified into the photoacoustic acquisition module or the photoacoustic imaging module.
The beam shaping module 305 includes a first lens 316, an aperture 317, and a second lens 318.
Alternatively, the first pulse laser 301 is configured to emit a near-infrared band pulse laser signal, and the second pulse laser 302 is configured to emit an ultraviolet band pulse laser signal. The near-infrared band pulse laser signals firstly irradiate the tissue slices, and the ultraviolet band pulse laser signals are used for irradiating the tissue slices at the first interval.
Firstly, a first pulse laser 301 emits pulse laser in a near-infrared band for one time to heat a tissue slice; then after the first time interval, the second pulse laser 302 emits a pulse laser signal in an ultraviolet band, after optical shaping, the pulse laser signal enters the scanning module 307 through the same path as the pulse laser signal with the near-infrared wavelength after being emitted by the reflector, and the pulse laser signal coming out of the scanning module 307 irradiates a tissue slice sample on an objective table in a coupling box after passing through a focusing lens objective 308; an ultrasonic transducer 312 with an acoustic lens 311 is arranged right above the sample, and the acoustic lens 311 is used for enabling the photoacoustic signal to be received by the ultrasonic transducer to the maximum extent through the acoustic lens, so that the receiving efficiency of the photoacoustic signal is improved, and light and sound are excited and received in a confocal manner, so that a good photoacoustic signal is further obtained.
The objective lens 308 is used for further processing the pulsed laser beam to make the size of the laser beam and the waveform energy meet the requirements of photoacoustic imaging, and the beam shaping module includes, but is not limited to, optical filters, diaphragms, apertures, focusing lenses, etc., various convex/concave lenses, grin lenses, C-lenses, etc.
The scanning module realizes high-resolution scanning in a small range by using the galvanometer, and simultaneously realizes large-range movement by matching with a mechanical displacement platform to obtain a full-range slice image.
The ultrasonic transducer 312, the signal amplifier 313 and the sampling module 314 are used for collecting and amplifying the photoacoustic signal and sending the photoacoustic signal to an image processing system such as a computer 315 for processing. It will be appreciated by those skilled in the art that other modules for shaping or filtering the signal, such as signal filters, may also be included. The sampling module may adopt a high-speed data acquisition card, and the like, which is not limited in this embodiment. The ultrasound transducer 312 is used to receive photoacoustic signals of the tissue slice; the signal amplifier can realize the amplification of weak signals, and the signal filter can reduce various noise interferences which may exist, so that the signal-to-noise ratio of the photoacoustic signals is improved, and convenience is provided for the reconstruction of photoacoustic signal images.
The image reconstruction module 315 processes the obtained photoacoustic signal of the slice, and obtains a photoacoustic image of the corresponding tissue slice through an algorithm. The image reconstruction module 315 may include at least one of various computing modules, such as a data processing module, a GPU module, and a software module.
It will be understood that all or some of the steps, systems of methods disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Claims (10)
1. A method of imaging a tissue slice, comprising:
the method comprises the following steps that a first pulse laser emits a first pulse laser scanning signal to a tissue slice to be detected, and the first pulse laser scanning signal is used for heating the tissue slice;
after the interval of the first time, a second pulse laser emits a second pulse laser scanning signal to the tissue slice, and the second pulse laser scanning signal is used for exciting the photoacoustic signal of the tissue slice;
receiving a photoacoustic signal excited by the second pulsed laser scanning signal from the tissue section;
determining a photoacoustic image of the tissue slice from the photoacoustic signals.
2. The imaging method according to claim 1, characterized in that:
the first pulse laser scanning signal is a pulse laser scanning signal of a near-infrared wave band;
the second pulse laser scanning signal is a pulse laser scanning signal of an ultraviolet band.
3. The imaging method according to claim 1, characterized in that:
the first time is determined according to the thermal relaxation time of the tissue section after the tissue section is irradiated by the first pulse laser scanning signal, the repetition frequency of the first pulse laser scanning signal and the repetition frequency of the second pulse laser scanning signal.
4. The imaging method according to claim 1, further comprising:
a first pulsed laser signal is emitted and,
the first pulse laser signal passes through the beam combiner and then passes through the scanning module to obtain a first pulse laser scanning signal;
a second pulsed laser signal is emitted and,
and after the second pulse laser signal is subjected to beam shaping, the second pulse laser signal is reflected by the beam combiner and is sent to the scanning module to obtain a second pulse laser scanning signal.
5. The imaging method according to claim 4, characterized in that:
and the galvanometer in the scanning module is used for scanning the tissue slices in a smaller range, and the displacement platform for placing the tissue slices is used for moving to scan the tissue slices in a larger range.
6. The imaging method according to claim 5, characterized in that:
and the motion parameters of the galvanometer and the motion parameters of the displacement platform are determined according to the repetition frequency of the first pulse laser signal and the second pulse laser signal.
7. A tissue slice imaging system, comprising:
a first pulse laser for emitting a first pulse laser signal;
the second pulse laser is used for transmitting a second pulse laser signal;
the beam shaping module is used for receiving the second pulse laser signal, shaping the second pulse laser signal and outputting the second pulse laser signal;
the beam combiner is used for receiving the first pulse laser signal and transmitting and outputting the first pulse laser signal; the second pulse laser device is used for receiving the shaped second pulse laser signal and outputting the second pulse laser signal in a reflection mode;
the scanning module is used for receiving a first pulse laser signal output by the beam combiner and outputting a first pulse laser scanning signal, and receiving a second pulse laser signal output by the beam combiner and outputting a second pulse laser scanning signal;
the displacement platform is used for placing the tissue slices to be detected;
a photoacoustic acquisition module for detecting a photoacoustic signal excited by the second pulsed laser scanning signal of the tissue slice;
a photoacoustic imaging module for determining a photoacoustic image of the tissue slice from the photoacoustic signal;
wherein the first pulsed laser scanning signal is used to heat the tissue slice.
8. The imaging system of claim 7,
the first pulse laser scanning signal is a pulse laser scanning signal of a near-infrared wave band;
the second pulse laser scanning signal is a pulse laser scanning signal of an ultraviolet band.
9. The imaging system of claim 7, wherein:
the second pulse laser emits the second pulse laser signal after a first time after the first pulse laser emits the first pulse laser signal; the first time is determined based on a thermal relaxation time of the tissue slice, a repetition rate of the first pulsed laser scan signal, and a repetition rate of the second pulsed laser scan signal.
10. An imaging system according to claim 7, wherein:
enabling, by the scanning module, a small-range scan of the tissue slice;
the tissue slice is scanned in a large range through the movement of the displacement platform;
the motion parameters of the scanning module and the motion parameters of the displacement platform are determined according to the repetition frequency of the first pulse laser signal and the second pulse laser signal.
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