1 Luminescence of Rare Earth Doped LaF3 Crystal LaF3 is an ideal low-phonon host for rare earthions due to its ability to form extensive solid solu-tions with all the RE ions.In 1964,professor Yen published his first ...1 Luminescence of Rare Earth Doped LaF3 Crystal LaF3 is an ideal low-phonon host for rare earthions due to its ability to form extensive solid solu-tions with all the RE ions.In 1964,professor Yen published his first paper on the Physical Review titled'Phonon-induced relaxation in excited opticalstates of trivalent praseodymium in LaF3'[1],whichwas Prof.Yen s very first work in the field of solidstate optical展开更多
Understanding the dynamics of ultrasonic excited microbubbles bound within microvessels is of significance for novel ultrasonic imaging, drug delivery and therapeutic biomedicad applications. A finite element model （...Understanding the dynamics of ultrasonic excited microbubbles bound within microvessels is of significance for novel ultrasonic imaging, drug delivery and therapeutic biomedicad applications. A finite element model （FEM） considering acoustic nonlinearity is developed to describe the asymmetric oscillation and acoustic response from mn encapsulated microbubble bound within a small vessel. Numerical simulation is performed for a 2 μm encapsulated microbubble bound within 8-20μm vessels using 2 MHz ultrasound excitation. The oscillation of the bound microbubble becomes more asymmetric under larger ultrasound pressure or within the smaller vessel. The normalized difference between the major and minor axes of epllipse is estimated to be 2.16%for the 8 μm vessel at an acoustic pressure of 0.5 MPa. In addition, the fundamental component of the acoustic scattering from the bound microbubble is enhanced by 6 dB while the second harmonic component is decreased by approximately 29 dB compared with the free microbubble.展开更多
Sub-harmonic contrast imaging promises to improve ultrasound imaging quality by taking advantage of increased contrast to tissue signal.The aim of this study is to examine the hysteretic nonlinearity of sub-harmonic c...Sub-harmonic contrast imaging promises to improve ultrasound imaging quality by taking advantage of increased contrast to tissue signal.The aim of this study is to examine the hysteretic nonlinearity of sub-harmonic component emitted from microbubbles.Two kinds of microbubble solutions,i.e.Sonovue■and a self-developed contrast agent,are utilized in the study.The hysteretic curves for increasing and decreasing acoustic pressure are theoretically predicted by the Marmottant model and confirmed by measurements.The results reveal that for both microbubble solutions,the development of the rising ramp undergoes three stages,i.e.occurrence,growth and saturation;while hysteresis effect appears in the descending ramp.Sono Vue■microbubbles exhibit better sub-harmonic performance over the self-developed UCAs microbubbles due to the difference of elastic properties of the shell.展开更多
Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teach...Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teaching etc. In this paper, marching cubes algorithm is adopted to reconstruct the 3-D images for the CT image sequence in DICOM format under theVC++6.0 and the visual package VTK platform. The relatively simple interactive operations such as rotation and transfer can be realized on the platform. Moreover, the normal vector and interior point are calculated to form the virtual clipping plane, which is then used to incise the 3-D object. Information of the virtual slice can be obtained, in the mean while the virtual slice images are displayed on the screen. The technique can realize the real time interaction extraction of virtual slice on 3-D CT image. The cuboids structured can be zoomed, moved and eircumrotated by operating mouse to incise the 3-D reconstruction object. Real time interaction can be realized by clipping the reconstruction object. The coordinates can be acquired by the mouse clicking in the 3D space, to realize the point mouse pick-up as well angle and distance interactive measurement. We can get quantitative information about 3-D images through measurement.展开更多
Propagation-based phase-contrast imaging was simulated based on paraxial Fresnel-Kirchoff diffraction integral and spherical wave illumination. Under a developed micro-CT system parameters, the effects of focal-spot s...Propagation-based phase-contrast imaging was simulated based on paraxial Fresnel-Kirchoff diffraction integral and spherical wave illumination. Under a developed micro-CT system parameters, the effects of focal-spot size and imaging geometry on phase-contrast imaging have been investigated using a 2-mm-thickness polystyrene edge phantom. An equivalent mono-energy was used to substitute the polychromatic spectrum of the micro-focus X-ray source. To consider effects of focal-spot size and detector resolution, the obtained phase-contrast image with an ideal point source was convolved with source intensity distribution and point spread function of detector. Simulations show reasonable influences of the two parameters which are in good agreement with experimental results.展开更多
文摘1 Luminescence of Rare Earth Doped LaF3 Crystal LaF3 is an ideal low-phonon host for rare earthions due to its ability to form extensive solid solu-tions with all the RE ions.In 1964,professor Yen published his first paper on the Physical Review titled'Phonon-induced relaxation in excited opticalstates of trivalent praseodymium in LaF3'[1],whichwas Prof.Yen s very first work in the field of solidstate optical
基金Supported by the National Basic Research Program of China under Grant No 2010CB732600, and the National Natural Science Foundation of China （10774071 and 10904094）.
文摘Understanding the dynamics of ultrasonic excited microbubbles bound within microvessels is of significance for novel ultrasonic imaging, drug delivery and therapeutic biomedicad applications. A finite element model （FEM） considering acoustic nonlinearity is developed to describe the asymmetric oscillation and acoustic response from mn encapsulated microbubble bound within a small vessel. Numerical simulation is performed for a 2 μm encapsulated microbubble bound within 8-20μm vessels using 2 MHz ultrasound excitation. The oscillation of the bound microbubble becomes more asymmetric under larger ultrasound pressure or within the smaller vessel. The normalized difference between the major and minor axes of epllipse is estimated to be 2.16%for the 8 μm vessel at an acoustic pressure of 0.5 MPa. In addition, the fundamental component of the acoustic scattering from the bound microbubble is enhanced by 6 dB while the second harmonic component is decreased by approximately 29 dB compared with the free microbubble.
基金Supported by the National Basic Research Program of China under Grant No 2010CB732600 andNational Natural Science Foundation of China under Grant Nos 10974093,11011130201 and 10904094 and Key Lab of Acoustics。
文摘Sub-harmonic contrast imaging promises to improve ultrasound imaging quality by taking advantage of increased contrast to tissue signal.The aim of this study is to examine the hysteretic nonlinearity of sub-harmonic component emitted from microbubbles.Two kinds of microbubble solutions,i.e.Sonovue■and a self-developed contrast agent,are utilized in the study.The hysteretic curves for increasing and decreasing acoustic pressure are theoretically predicted by the Marmottant model and confirmed by measurements.The results reveal that for both microbubble solutions,the development of the rising ramp undergoes three stages,i.e.occurrence,growth and saturation;while hysteresis effect appears in the descending ramp.Sono Vue■microbubbles exhibit better sub-harmonic performance over the self-developed UCAs microbubbles due to the difference of elastic properties of the shell.
基金National 973 Basic Research Program of Chinagrant number:2010CB732600+4 种基金Major Research Equipment Fund of the Chinese Academy of Sciences and Knowledge Innovation Project of the Chinese Academy of Sciences,2008 Shenzhen Controversial Technology Innovation Research Projectsgrant number:FG200805230224AConcentration plan of innovation sources of Shenzhen-R&D projects of international cooperation on science and technologygrant number:ZYA200903260065ANatural Science Foundation of Guangdong Province,China 8478922035-X0007007
文摘Three-dimensional medical image visualization becomes an essential part for medical field, including computer aided diagnosis, surgery planning and simulation, artificial limb surgery, radiotherapy planning, and teaching etc. In this paper, marching cubes algorithm is adopted to reconstruct the 3-D images for the CT image sequence in DICOM format under theVC++6.0 and the visual package VTK platform. The relatively simple interactive operations such as rotation and transfer can be realized on the platform. Moreover, the normal vector and interior point are calculated to form the virtual clipping plane, which is then used to incise the 3-D object. Information of the virtual slice can be obtained, in the mean while the virtual slice images are displayed on the screen. The technique can realize the real time interaction extraction of virtual slice on 3-D CT image. The cuboids structured can be zoomed, moved and eircumrotated by operating mouse to incise the 3-D reconstruction object. Real time interaction can be realized by clipping the reconstruction object. The coordinates can be acquired by the mouse clicking in the 3D space, to realize the point mouse pick-up as well angle and distance interactive measurement. We can get quantitative information about 3-D images through measurement.
基金National Natural Science Foundation of Chinagrant number:61002041,61102161+3 种基金National 973 Basic Research Program of Chinagrant number:2010CB7326002010-Guangdong Province Innovational Research Team Program and Programs of Shenzhengrant number:JC201005270313A,JC201005280493A,JC201005280581A,ZYA201006300034A
文摘Propagation-based phase-contrast imaging was simulated based on paraxial Fresnel-Kirchoff diffraction integral and spherical wave illumination. Under a developed micro-CT system parameters, the effects of focal-spot size and imaging geometry on phase-contrast imaging have been investigated using a 2-mm-thickness polystyrene edge phantom. An equivalent mono-energy was used to substitute the polychromatic spectrum of the micro-focus X-ray source. To consider effects of focal-spot size and detector resolution, the obtained phase-contrast image with an ideal point source was convolved with source intensity distribution and point spread function of detector. Simulations show reasonable influences of the two parameters which are in good agreement with experimental results.
