Photoacoustic imaging combines the advantages of optical imaging and ultrasound imaging, on the one hand, the signal used to reconstruct the image in photoacoustic imaging is an ultrasound signal, and the scattering of ultrasound signals by physiological tissues is two to three orders of magnitude lower than that of light signals, so it can provide a deeper imaging depth and higher spatial resolution; on the other hand, photoacoustic imaging is performed in accordance with the selective absorption of different tissues of visible light, near-infrared light or On the other hand, photoacoustic imaging is based on the selective absorption of different tissues of visible light, near-infrared light or radio frequency electromagnetic waves, using a specific wavelength laser pulse to irradiate the tissues, and indirectly on the distribution of pulse energy absorption in the physiological tissues for imaging, imaging of the "absorbed" light, which can not be done in pure optical imaging, therefore This is not possible in purely optical imaging, so the optical contrast between different tissues is higher in photoacoustic images than in pure ultrasound imaging. Photoacoustic imaging has the following characteristics compared with traditional medical imaging technology:
First, due to the narrow linewidth of the laser, the use of biological tissues of the high spectral selective absorption differences, photoacoustic imaging can realize the selective excitation of highly specific spectral tissues, not only to reflect the structural characteristics of the tissue, but also to achieve the function of the imaging, the creation of a new imaging method and technology means that are different from the traditional medical imaging technology.
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Second, photoacoustic imaging combines the advantages of optical imaging and acoustic imaging. On the one hand, it can penetrate deeper than pure optical imaging (it can break through the "soft" depth limit (~1mm) of high-resolution optical imaging such as laser*** focusing microscopy (LCSM), two-photon excitation microscopy (TPEF), optical weak coherence tomography (OCT), etc.); on the other hand, it has a higher resolution than traditional MRI and PET imaging; on the other hand, it has a higher resolution than traditional MRI and PET imaging; and on the other hand, it has a higher resolution than traditional MRI and PET imaging. On the other hand, it has higher resolution than traditional MRI and PET imaging; its image resolution can reach sub-micron and micron scale, which can realize high-resolution molecular imaging.
Third, photoacoustic imaging is a non-invasive imaging technique, which is very important for in vivo imaging. Because the laser power density used is below the damage threshold of biological tissues, and the intensity of the ultrasound field generated in the tissues is far below the damage threshold of the tissues, photoacoustic imaging is a non-invasive, non-ionizing and non-invasive imaging technique.
Fourth, with the integration and miniaturization of the photoacoustic imaging system, the imaging system is cheaper and more convenient to use than the traditional MRI and PET brain function imaging systems, which is conducive to popularization and promotion.
Therefore, as an emerging medical imaging technology, non-destructive photoacoustic imaging is capable of obtaining sufficiently high resolution and image contrast at a certain depth, and the image transmits a large amount of information, which can provide both morphological and functional information, and has a broad application prospect in the field of biomedical applications.