Short-wave infrared imaging method and system of silicon-based camera based on near-infrared enhancement

Abstract

The invention discloses a short-wave infrared imaging method and system based on a near-infrared enhanced silicon-based camera, and belongs to the field of medical imaging, and the system comprises a fluorescence excitation light source, the near-infrared enhanced silicon-based camera, a short-wave infrared lens, and a long-pass optical filter with the cut-off wavelength of 900-1000 nm. Selecting an optimal silicon-based camera according to the spectrum and light intensity of the imaging fluorescent molecules, and building a test system based on the optimal silicon-based camera; then imaging the double-layer tissue fluorescent bionic phantom by using a silicon-based camera under different optical filters, and researching the depth resolution and the signal-to-multiple ratio of the camera in different wavebands; and selecting an optimal imaging wave band to obtain the short-wave infrared imaging method based on the silicon-based camera. The double-layer tissue fluorescent bionic motif is imaged through a short-wave infrared camera, and the performance of the double-layer tissue fluorescent bionic motif is compared with the performance of the imaging method. The method is simple and convenient to operate, low in cost and high in resolution, and is expected to develop a new possibility for application scenes limited by the sensor technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of medical imaging, fluorescence image-guided surgery and diagnostic imaging, and particularly relates to a short-wave infrared imaging method and system based on a near-infrared enhanced silicon-based camera. Background Art

[0002] Fluorescence imaging offers advantages such as non-invasiveness, lack of radioactivity, low cost, high resolution, and real-time performance, spurring the development of various clinical techniques, including fluorescence image-guided surgery and diagnostic imaging. The short-wave infrared (SWIR) window (1000-1700 nm) promises to offer superior imaging quality compared to the visible and first near-infrared windows (700-900 nm) due to reduced tissue autofluorescence, reduced photon scattering, and lower levels of photon absorption at longer wavelengths. However, the clinical application of SWIR imaging remains limited due to a lack of clinically approved fluorophores and suitable imaging equipment. On the one hand, the currently available SWIR fluorescer is indocyanine green (ICG), which has an emission peak in the first near-infrared window (800–860 nm). However, its fluorescence spectrum exhibits a broad shoulder and a spectral tail extending into the SWIR. On the other hand, InGaAs cameras for SWIR applications still face challenges such as high manufacturing cost, large pixel size, low pixel count, and high thermal noise. Furthermore, the weak signal of ICG in the SWIR window necessitates the use of highly sensitive InGaAs cameras to enhance system sensitivity in the SWIR. High-sensitivity InGaAs cameras require integrated cooling and heat dissipation modules, which makes them heavy, bulky, and inconvenient to use. Summary of the Invention

[0003] In view of the above problems, the object of the present invention is to provide a short-wave infrared imaging method and system based on a silicon-based camera with near-infrared enhancement.

[0004] The object of the present invention is achieved through the following technical solution: a short-wave infrared imaging method based on a silicon-based camera with near-infrared enhancement, comprising the following steps:

[0005] (1) Select the optimal near-infrared enhanced silicon-based camera based on the imaging spectrum of the fluorescent molecules and the spectral response curves and sensitivities of different silicon-based cameras;

[0006] (2) The silicon-based camera is equipped with a lens with adjustable focal length, a near-infrared fluorescence excitation light source is selected, the illumination light is output using an optical fiber, and the excitation light power is measured using an optical power meter;

[0007] (3) Select several sets of filters suitable for imaging the fluorescent molecules, install them on the filter wheel, install the filter wheel directly below the lens, rotate the filter wheel to move the filters to the bottom of the camera in sequence, adjust the exposure time, and image the tissue fluorescent bionic phantom in different bands;

[0008] (4) Processing the images obtained by imaging the tissue fluorescence biomimetic phantom in different bands, calculating the depth resolution, and selecting the optimal band suitable for imaging the fluorescence molecule; obtaining a silicon-based camera based on near-infrared enhancement;

[0009] (5) The near-infrared enhanced silicon-based camera was replaced with a short-wave infrared camera, and imaging photos of the fluorescent bionic model were taken under filters of different bands. The optimal result was selected and compared with the imaging effect of the optimal band of the silicon-based camera to prove the feasibility of the short-wave infrared imaging method based on the silicon-based camera.

[0010] Furthermore, the near-infrared enhanced silicon-based camera has a quantum efficiency of not less than 20% at 900-1000 nm.

[0011] Furthermore, the selection of the optimal near-infrared enhanced silicon-based camera includes: selecting silicon-based cameras with different parameters, testing their signal-to-noise ratios in different bands under the same light intensity and exposure time, and selecting the camera with the best signal-to-noise ratio at 900-1000nm as the optimal near-infrared enhanced silicon-based camera.

[0012] Furthermore, the lens is a short-wave infrared lens of 700-1700nm.

[0013] Furthermore, the near-infrared fluorescence excitation light source is a fluorescence excitation light source with an excitation light wavelength of 750-820 nm and an excitation light power of 5-100 mW.

[0014] Furthermore, the imaging of the tissue fluorescence biomimetic phantom in different bands includes: selecting an 850 nm bandpass filter for the first near-infrared window imaging based on the emission spectrum of the selected fluorescent molecule, and selecting bandpass and longpass filters with different wavelength ranges in the 900-1000 nm band, and testing the imaging clarity when they are assembled on the camera.

[0015] Furthermore, the filter is in close contact with the lens to prevent interference from ambient light and light leakage from the light source.

[0016] Furthermore, the optimal filter is a long-pass filter with a cut-off wavelength in the range of 900-1000 nm.

[0017] Furthermore, the short-wave infrared camera selects a standard InGaAs camera and a deep-cooled InGaAs camera, and the filter selects a bandpass and longpass filter in the 900-1300 nm band.

[0018] The present invention also provides a short-wave infrared imaging system based on a near-infrared enhanced silicon-based camera, comprising:

[0019] Excitation light source: fluorescence excitation light source with an excitation wavelength of 750-820 nm;

[0020] Near-infrared enhanced silicon-based camera: quantum efficiency of not less than 20% at 900-1000 nm;

[0021] Short-wave infrared lens: 700-1700 nm;

[0022] Filter set: Long-pass filter with a cut-off wavelength in the range of 900-1000 nm.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. This invention utilizes a near-infrared-enhanced silicon-based camera as the imaging device and a 900-1000 nm longpass filter for wavelength selection, achieving shortwave infrared imaging. Earlier reports using near-infrared-enhanced silicon-based cameras as imaging devices typically used signals in the 800-880 nm band for imaging, resulting in inferior depth resolution and signal-to-background ratio compared to imaging with a 900-1000 nm longpass filter.

[0025] 2. The present invention uses a double-layer tissue bionic phantom to verify the proposed short-wave infrared imaging method and system based on a near-infrared enhanced silicon-based camera, compares its imaging effect with that of an InGaAs camera, and proves that the proposed method has higher depth resolution and signal-to-background ratio than traditional InGaAs cameras.

[0026] 3. The method of the present invention is simple to operate, low-cost, high-resolution, requires minimal equipment, and is easily miniaturized. The imaging band of the device can be flexibly changed according to the actual scenario requirements, and has broad application prospects in fluorescence image-guided surgery and diagnostic imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0028] Figure 1 Schematic diagram of a short-wave infrared imaging system based on a near-infrared enhanced silicon-based camera provided by the present invention;

[0029] Figure 2 Schematic diagram of the double-layer tissue fluorescence biomimetic phantom used in the present invention;

[0030] Figure 3Schematic diagram of imaging of a fluorescent bionic phantom by a near-infrared enhanced silicon-based camera using different filters when the scatterer thickness is 6 mm obtained in Example 4 of the present invention;

[0031] Figure 4 This is a comparison chart of the resolutions of different filters obtained in Example 5 of the present invention at different scattering depths;

[0032] Figure 5 Schematic diagram of imaging of a fluorescent bionic phantom using the proposed method and a standard InGaAs camera when the scatterer thickness is 7 mm obtained in Example 6 of the present invention;

[0033] Figure 6 This is the imaging result of biological tissue obtained in Example 7 of the present invention. DETAILED DESCRIPTION

[0034] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent like or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention, as detailed in the appended claims.

[0035] The terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The singular forms "a," "the," and "the" used in this invention and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] It should be understood that although the terms "first," "second," "third," etc. may be used in the present invention to describe various information, such information should not be limited to these terms. These terms are merely used to distinguish information of the same type from one another. For example, first information may also be referred to as second information, and similarly, second information may also be referred to as first information, without departing from the scope of the present invention. Depending on the context, the term "if" as used herein may be interpreted as "when," "when," or "in response to determining."

[0037] The present invention will be described in detail below with reference to the accompanying drawings. Unless there is any conflict, the features of the following embodiments and implementations may be combined with each other.

[0038] An embodiment of the present invention provides a short-wave infrared imaging method using a silicon-based camera with near-infrared enhancement, comprising the following steps:

[0039] Step 1: Select the optimal near-infrared enhanced silicon-based camera based on the imaging spectrum of the fluorescent molecule and the spectral response curves and sensitivities of different silicon-based cameras.

[0040] Step 2: Equip the silicon-based camera with a lens with adjustable focal length, select a near-infrared fluorescence excitation light source, use optical fiber to output illumination light, and use an optical power meter to measure the excitation light power.

[0041] Step 3: Select several sets of filters suitable for the fluorescence molecule imaging, install them on the filter wheel, install the filter wheel just below the lens, rotate the filter wheel to move the filters to the bottom of the camera in sequence, adjust the exposure time, and image the tissue fluorescence bionic phantom in different bands; the tissue fluorescence bionic phantom is as follows: Figure 2 As shown, the fluorescent molecule solution is sealed in a mold, a resolution plate is placed on it and fixed, the mold is placed in a culture dish, and fat emulsion is added as a scatterer.

[0042] Step 4: Process the image and select the optimal filter for the silicon-based camera to obtain a silicon-based camera based on near-infrared enhancement.

[0043] Step 5: Replace the near-infrared enhanced silicon-based camera with a short-wave infrared camera, take imaging photos of the fluorescent bionic model under different wavelength filters, and compare them with the silicon-based camera.

[0044] like Figure 1 As shown, an embodiment of the present invention further provides a short-wave infrared imaging system based on a near-infrared enhanced silicon-based camera, comprising:

[0045] Excitation light source: fluorescence excitation light source with an excitation wavelength of 750-820 nm;

[0046] Near-infrared enhanced silicon-based camera: quantum efficiency of not less than 20% at 900-1000 nm;

[0047] Short-wave infrared lens: 700-1700 nm;

[0048] Filter set: Long-pass filter with a cut-off wavelength in the range of 900-1000 nm.

[0049] Example 1:

[0050] (1) A silicon-based camera with a quantum efficiency of less than 20% at 900-1000nm was installed on a robotic arm, equipped with a lens with adjustable focal length, and a near-infrared fluorescence excitation light source was selected. The illumination light was output using optical fiber, and the light power was controlled at 50mW.

[0051] (2) Select imaging filters of 850nm BP, 900nm LP, 950nm LP, 960nm BP, and 1000nm LP, install them on the filter wheel, install the filter wheel directly below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom in different bands.

[0052] (3) Due to the insufficient quantum efficiency of the camera, clear images cannot be obtained above the 900nm band.

[0053] Example 2:

[0054] (1) According to the imaging spectrum of fluorescent molecules and the spectral response curves of different silicon-based cameras, the optimal near-infrared enhanced silicon-based camera is selected.

[0055] (2) The silicon-based camera is equipped with a lens with adjustable focal length, a near-infrared fluorescence excitation light source is selected, the illumination light is output using an optical fiber, the excitation light power is measured using an optical power meter, and the excitation light power is controlled at 500 mW.

[0056] (3) Select imaging filters of 850nm BP, 900nm LP, 950nm LP, 960nm BP, and 1000nm LP, install them on the filter wheel, install the filter wheel directly below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom in different bands.

[0057] (4) Due to excessive power, ICG undergoes photoquenching and a clear image cannot be obtained.

[0058] Example 3:

[0059] (1) According to the imaging spectrum of fluorescent molecules and the spectral response curves of different silicon-based cameras, the optimal near-infrared enhanced silicon-based camera is selected.

[0060] (2) A near-infrared enhanced silicon-based camera is mounted on a robotic arm and equipped with a lens with adjustable focal length. The position of the camera is moved by adjusting the robotic arm. An 808nm laser is selected for illumination, and the illumination light is output using an optical fiber. The excitation light power is measured using an optical power meter and the light power is controlled at 50mW.

[0061] (3) Select imaging filters of 1000nm LP, 1050nm LP, and 1100nm LP, install them on the filter wheel, install the filter wheel directly below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom in different bands.

[0062] (4) Because the cutoff wavelength of the filter is too long, the fluorescence signal is too weak and a clear image cannot be obtained.

[0063] Example 4:

[0064] (1) According to the imaging spectrum of fluorescent molecules and the spectral response curves of different silicon-based cameras, the optimal near-infrared enhanced silicon-based camera is selected.

[0065] (2) A near-infrared enhanced silicon-based camera is mounted on a robotic arm and equipped with a lens with adjustable focal length. The position of the camera is moved by adjusting the robotic arm. An 808nm laser is selected for illumination, and the illumination light is output using an optical fiber. The excitation light power is measured using an optical power meter and the light power is controlled at 50mW.

[0066] (3) Select imaging filters of 850nm BP, 900nm LP, 950nm LP, 960nm BP and 1000nm LP, install them on the filter wheel, install the filter wheel just below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom covered with 6mm scatterers in different bands, such as Figure 3 shown.

[0067] (4) After processing the image, it can be seen that 950nm LP and 1000nm LP have the best depth resolution, both better than 850nm BP. By selecting the optimal filter of the silicon-based camera, a short-wave infrared imaging method based on the silicon-based camera with near-infrared enhancement is obtained.

[0068] Example 5:

[0069] (1) According to the imaging spectrum of fluorescent molecules and the spectral response curves of different silicon-based cameras, the optimal near-infrared enhanced silicon-based camera is selected.

[0070] (2) A near-infrared enhanced silicon-based camera is mounted on a robotic arm and equipped with a lens with adjustable focal length. The position of the camera is moved by adjusting the robotic arm. An 808nm laser is selected for illumination, and the illumination light is output using an optical fiber. The excitation light power is measured using an optical power meter and the light power is controlled at 50mW.

[0071] (3) Select imaging filters of 850nm BP, 900nm LP, 950nm LP, 960nm BP and 1000nm LP, install them on the filter wheel, install the filter wheel just below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom covered with 2mm, 3mm, 4mm, 5mm, 6mm and 7mm scatterers in different bands, such as Figure 4 shown.

[0072] (4) The image is processed, the depth resolution is calculated, and the optimal filter 950nm LP for the silicon-based camera is selected to obtain a short-wave infrared imaging method based on a silicon-based camera with near-infrared enhancement.

[0073] Example 6:

[0074] (1) According to the imaging spectrum of fluorescent molecules and the spectral response curves of different silicon-based cameras, the optimal near-infrared enhanced silicon-based camera is selected.

[0075] (2) A near-infrared enhanced silicon-based camera is mounted on a robotic arm and equipped with a lens with adjustable focal length. The position of the camera is moved by adjusting the robotic arm. An 808nm laser is selected for illumination, and the illumination light is output using an optical fiber. The excitation light power is measured using an optical power meter and the light power is controlled at 50mW.

[0076] (3) Select imaging filters of 850nm BP, 900nm LP, 950nm LP, 960nm BP and 1000nm LP, install them on the filter wheel, install the filter wheel just below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom covered with 7mm scatterers in different bands, such as Figure 5 shown.

[0077] (4) The image is processed and the optimal filter of the silicon-based camera is selected to obtain a short-wave infrared imaging method based on a silicon-based camera with near-infrared enhancement.

[0078] (5) Replace the near-infrared enhanced silicon-based camera with a standard InGaAs camera and take imaging photos of the fluorescent bionic model under different wavelength filters, such as Figure 5 As shown in the figure, the standard InGaAs camera has the best imaging effect at 900nm LP and 950nm LP. However, compared with the silicon-based camera, it is worse than the near-infrared enhanced silicon-based camera equipped with 950nm LP and 1000nm LP filters.

[0079] Example 7:

[0080] (1) According to the imaging spectrum of fluorescent molecules and the spectral response curves of different silicon-based cameras, the optimal near-infrared enhanced silicon-based camera is selected.

[0081] (2) A near-infrared enhanced silicon-based camera is mounted on a robotic arm and equipped with a lens with adjustable focal length. The position of the camera is moved by adjusting the robotic arm. An 808nm laser is selected for illumination, and the illumination light is output using an optical fiber. The excitation light power is measured using an optical power meter and the light power is controlled at 50mW.

[0082] (3) Select imaging filters of 850nm BP, 900nm LP, 950nm LP, 960nm BP, and 1000nm LP, install them on the filter wheel, install the filter wheel directly below the lens, rotate the filter wheel to move the filters to the bottom of the camera in turn, adjust the exposure time, and image the tissue fluorescence bionic phantom in different bands.

[0083] (4) The image is processed and the optimal filter of the silicon-based camera is selected to obtain a short-wave infrared imaging method and system based on a silicon-based camera with near-infrared enhancement.

[0084] (5) Use this system to perform short-wave infrared imaging of biological tissues, such as Figure 6 shown.

[0085] The present invention is based on near-infrared enhanced silicon-based camera technology, and uses the fluorescence emitted by ICG in the 900-1100nm band or a part of the 900-1100nm band to perform imaging. Compared with the first near-infrared window fluorescence imaging, this method can achieve better imaging effects in key indicators such as depth resolution and signal-to-background ratio. Compared with traditional ICG-based short-wave infrared imaging, the use of high-sensitivity InGaAs cameras can be avoided, and it has the advantages of lower system cost, higher imaging pixel density, less thermal noise, lower thermal management requirements, smaller weight, more mature image preprocessing algorithms, and simpler deployment. In addition, the method adopted by the present invention is expected to be applied to various scenarios that are limited by sensor technology. For example, in scenarios such as flexible endoscopes and rigid endoscopes, short-wave infrared fluorescence imaging can be performed without switching the design and overall architecture.

[0086] The above embodiments are intended only to illustrate the design concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. The scope of protection of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design concepts disclosed in the present invention are within the scope of protection of the present invention.

Claims

1. A short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera, characterized in that: The following steps are involved: Select the optimal near-infrared enhanced silicon-based camera based on the imaging spectrum of the fluorescent molecules and the spectral response curves and sensitivities of different silicon-based cameras; The silicon-based camera is equipped with a lens with adjustable focal length, a near-infrared fluorescence excitation light source is selected, the illumination light is output using an optical fiber, and the excitation light power is measured using an optical power meter; Select several sets of filters suitable for imaging the fluorescent molecules, install them on the filter wheel, install the filter wheel directly below the lens, adjust the exposure time, and image the tissue fluorescent bionic phantom in different bands; Processing images obtained by imaging the tissue fluorescence bionic phantom at different wavelengths, calculating the depth resolution, and selecting the optimal wavelength suitable for the fluorescence molecular imaging; The near-infrared enhanced silicon-based camera was replaced with a short-wave infrared camera, and imaging photos of the fluorescent bionic model were taken under different wavelength filters. The optimal result was selected and compared with the imaging clarity of the optimal band of the silicon-based camera. Among them, the imaging clarity of the optimal band of the silicon-based camera was better than that of the short-wave infrared camera.

2. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The near-infrared enhanced silicon-based camera has a quantum efficiency of not less than 20% at 900-1000 nm.

3. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The method of selecting the optimal near-infrared enhanced silicon-based camera includes: selecting silicon-based cameras with different parameters, testing their signal-to-noise ratios in different bands under the same light intensity and exposure time, and selecting the camera with the best signal-to-noise ratio at 900-1000nm as the optimal near-infrared enhanced silicon-based camera.

4. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The lens is a short-wave infrared lens of 700-1700nm.

5. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The near-infrared fluorescence excitation light source is a fluorescence excitation light source with an excitation light wavelength of 750-820 nm and an excitation light power of 5-100 mW.

6. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The imaging of the tissue fluorescence biomimetic phantom in different bands includes: selecting an 850 nm bandpass filter for the first near-infrared window imaging based on the emission spectrum of the selected fluorescent molecule, selecting bandpass and longpass filters with different wavelength ranges in the 900-1000 nm band, and testing the imaging clarity when they are assembled on the camera.

7. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The filter is closely attached to the lens to prevent interference from ambient light and light leakage from the light source.

8. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The optimal filter is a long-pass filter with a cut-off wavelength in the range of 900-1000 nm.

9. The short-wave infrared imaging method based on a near-infrared enhanced silicon-based camera according to claim 1, characterized in that: The short-wave infrared camera is a standard InGaAs camera and a deep-cooled InGaAs camera, and the filter is a bandpass and longpass filter in the 900-1300 nm band.

10. A short-wave infrared imaging system based on a near-infrared enhanced silicon-based camera, used to implement the method according to any one of claims 1 to 8, characterized in that: include: Excitation light source: fluorescence excitation light source with an excitation wavelength of 750-820 nm; Near-infrared enhanced silicon-based camera: quantum efficiency of not less than 20% at 900-1000 nm; Short-wave infrared lens: 700-1700 nm; Filter set: Long-pass filter with a cut-off wavelength in the range of 900-1000 nm.

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