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1.
袁毅  杨思华 《中国物理 B》2012,21(5):54211-054211
A reflection-mode photoacoustic microscope using a hollow focused ultrasound transducer is developed for highresolution in vivo imaging.A confocal structure of the laser and the ultrasound is used to improve the system resolution.The axial and lateral resolutions of the system are measured to be ~ 32 μm and ~ 58 μm,respectively.Ex vivo and in vivo modes are tested to validate the imaging capability of the photoacoustic microscope.The adjacent vein and artery can be seen clearly from the reconstructed photoacoustic images.The results demonstrate that the reflectionmode photoacoustic microscope can be used for high-resolution imaging of micro-blood vessels,which would be of great benefit for monitoring the neovascularization in tumor angiogenesis.  相似文献   

2.
Photoacoustic tomography (PAT) is a powerful imaging merits and most compelling features of light and sound, technique for medical diagnosis because it combines the We describe a PAT experimental system constructed in our laboratory which consists of a Q-switched Nd:YAG pulse laser operating at 532nm with a 8-ns pulse width to generate the photoacoustic signals from a biological sample. Two-dimensional photoacoustic imaging of blood vessel networks lcm below the tissue surface is achieved, We also successfully demonstrate that the system is capable of imaging the blood vessels over the ex vivo rat brain with skull and skin intact.  相似文献   

3.
A photoacoustic system with an annular transducer array is presented for rapid, high-resolution photoacoustic tomography of animals. An eight-channel data acquisition system is applied to capture the photoacoustic signals by using multiplexing and the total time of data acquisition and transferring is within 3 s. A limited-view filtered back projection algorithm is used to reconstruct the photoacoustic images. Experiments are performed on a mouse head and a rabbit head and clear photoacoustic images are obtained. The experimental results demonstrate that this imaging system holds the potential for imaging the human brain.  相似文献   

4.
Feasibility of photoacoustic tomography for ophthalmology   总被引:2,自引:0,他引:2  
For the eyeball composed of membrane and liquid,the contrast of ultrasound imaging is not high due to its small variance in acoustic impedance.As a new imaging modality,photoacoustic tomography combines the advantages of pure optical and ultrasonic imaging together and can provide high resolution,high contrast images.In this paper,the feasibility of photoacoustic tomography for ophthalmology is studied experimentally.A Q-switched Nd:YAG pulsed laser with 7-ns pulse width is used to generate photoacoustic signal of a porcine eyeball in vitro.The two-dimensional(2D)optical absorption image of the entire eyeball is reconstructed by time-domain spherical back projection algorithm.The imaging results agree well with the histological structure of the eyeball and show a high imaging contrast.  相似文献   

5.
Photoacoustic tomography (PAT) is presented to in vivo monitor neovascularization in tumour angiogenesis with high resolution and high contrast images in a rat. With a circular scan system, the photoacoustic signal, generated by laser pulses at a wavelength of 532nm from a Q-switched Nd:YAG laser is captured by a hydrophone with a diameter of 1 mm and a sensitivity of 850nV/Pa. The vascular structure around the rat tumour is imaged clearly, with optimal contrast, because blood has strong absorption near this wavelength. Serial noninvasive photoacoustic images of neovascularization in tumour angiogenesis are also obtained consecutively from a growing tumour implanted under the skin of a rat over a period of two weeks. This work demonstrates that PAT can potentially provide a powerful tool for tumour angiogenesis detection in cancer research. It will bring us closer to clinical applications for tumour diagnosis and treatment monitoring.  相似文献   

6.
Photoacoustic(PA) imaging has drawn tremendous research interest for various applications in biomedicine and experienced exponential growth over the past decade. Since the scattering effect of biological tissue on ultrasound is two-to three-orders magnitude weaker than that of light, photoacoustic imaging can effectively improve the imaging depth.However, as the depth of imaging further increases, the incident light is seriously affected by scattering that the generated photoacoustic signal is very weak and the signal-to-noise ratio(SNR) is quite low. Low SNR signals can reduce imaging quality and even cause imaging failure. In this paper, we proposed a new wavefront shaping and imaging method of low SNR photoacoustic signal using digital micromirror device(DMD) based superpixel method. We combined the superpixel method with DMD to modulate the phase and amplitude of the incident light, and the genetic algorithm(GA) was used as the wavefront shaping algorithm. The enhancement of the photoacoustic signal reached 10.46. Then we performed scanning imaging by moving the absorber with the translation stage. A clear image with contrast of 8.57 was obtained while imaging with original photoacoustic signals could not be achieved. The proposed method opens new perspectives for imaging with weak photoacoustic signals.  相似文献   

7.
We report tumor detection using a photoacoustic technique for the imaging of angiogenesis and monitoring of agent pharmacokinetics on an animal model. We take 532-nm laser pulses to excite photoacoustic signals of blood vessels with acquisition by a broadband hydrophone, and the morphological characteristics of tumor angiogenesis are successfully image depicted. Furthermore, tumor pharmacokinetics is preformed and analyzed with fast multielement photoacoustic imaging of the intravenous-injected indocyanine green (ICG). Photoacoustic signals of ICG are excited with 805 nm laser pulses and recorded by transducer array as a function of time. The difference between the photoacoustic signal from the tumor side and that from the normal side is observed, and the ICG clearance velocity in the tumor area is found to lag behind that in the normal area. Experimental results demonstrate that photoacoustie imaging of morphological parameter and pharmacokinetics with specific agent may provide high sensitive approach for tumor detection and localization.  相似文献   

8.
A fluorescence molecular tomography system for in vivo tumor imaging is developed using a 748-nm continuous wave diode laser as an excitation source.A high sensitivity cooled charge-coupled device (CCD) camera with excitation and emission filters is utilized to obtain the excitation and fluorescence images.The laser beam performs fast raster scanning using a dual-axis galvanometric scanner.The accuracy of the laser spot position at the source window is within ±200 μm.Based on the phantom experimental results,the spatial resolution is less than 1.7 mm,and the relative quantitation error is about 10%.In vivo imaging of a tumor-bearing nude mouse tagged with near-infrared dye demonstrates the feasibility of the system.  相似文献   

9.
Imitating micro-lens array for integral imaging   总被引:1,自引:0,他引:1  
<正>Integral imaging is a true,three-dimensional(3D) display technology that captures and reconstructs 3D scenes using two-dimensional(2D) micro-lens arrays.The manufacturing technique of micro-lens arrays is complicated and expensive,thus limiting the application of the technology.An imitating micro-lens array for integral imaging is presented in this letter.Imitating micro-lens array is composed of a cheap lenticular lens and a parallax barrier.The relationship of the parameters of the imitating micro-lens array is analyzed and the parameter formulae are deduced.The arrangement of pixels under a cell of the imitating micro-lens array is presented.The imitating micro-lens array is simulated using ASAP software,and the results prove that the designed imitating micro-lens array is effective.A 3D scene is reconstructed on a 3D display that consists of the imitating micro-lens array and a 17-inch flat panel display.  相似文献   

10.
Optical whispering-gallery microresonators have attracted considerable interest for ultrasensitive ultrasound detection and photoacoustic imaging because of the combination of high quality factors and small cavity sizes.In the last decade,ultrasonic sensors with on-chip microcavities have been extensively developed;however,they are unsuitable for the near-field photoacoustic microscopy of micro/nanoscale objects in complex biological environments and endoscopic imaging.In this work,we developed ultrasonic sensors using two types of encapsulated microsphere resonators with different cavity materials.A noise equivalent pressure of as low as 160 Pa at 20 MHz was achieved with the acoustic response up to 70 MHz at-6 d B.Furthermore,the microsensor was used for photoacoustic microscopy in which we successfully performed 3 D imaging of hairs and leaf veins.The microsphere ultrasonic sensor has considerable potential as a probe-type ultrasonic detector for near-field photoacoustic microscopy of micro/nanoscale objects such as subcellular structures and high-resolution endoscopic photoacoustic imaging with its high sensitivity and wide bandwidth.  相似文献   

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