Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform ...Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. The amplitude of sinusoidal motion was set to an amplitude of ±1 cm. The period of the motion was adjustable and set to 3.5 s. Phantom objects of two eggs were placed in a Styrofoam block, which in turn were placed on the motion platform. These objects were used to simulate volumes of interest undergoing ideal periodic motion. CT data of static phantom were acquired using a multi-slice general electric (GE) LightSpeed 16-slice CT scanner in an axial mode. And the CT data of periodical motion phantom were acquired in an axial and cine-mode scan. A software program was developed by using VC++ and VTK software tools to resort the CT data and reconstruct the 4D-CT. Then all of the CT data with same phase were sorted by the program into the same series based on the similarity principle of spatial adjacent images and mutual information measure among them, and 3D reconstruction of different phase CT data were completed by using the software. Results:All of the CT data were sorted accurately into different series based on the similarity principle of spatial adjacent images and mutual information measures among them. Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced significantly, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusion:Time-resolved 4D-CT reconstruction can be implemented with any general multi-slice CT scanners based on the similarity principle of spatial adjacent images and mutual information measure.The process of the 4D-CT data acquisition and reconstruction were not restricted to the hardware or software of the CT scanner and has the feasibility ,which extensive applicability.展开更多
Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial role.However,Fe leaching occurs during the reaction ...Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial role.However,Fe leaching occurs during the reaction due to thermodynamic instability,which has resulted in conflicting reports within the literature regarding its role.To clarify this point,we propose a strategy consisting of modulating the electronic orbital occupancy to suppress the extensive loss of Fe atoms during the OER process.Theoretical calculations,in-situ X-ray photoelectron spectroscopy,molecular dynamics simulations,and a series of characterization showed that the stable presence of Fe not only accelerates the electron transfer process but also optimizes the reaction barriers of the oxygen evolution intermediates,promoting the phase transition of Fe_(5)Ni_(4)S_(8)to highly active catalytic species.The modulated Fe_(5)Ni_(4)S_(8)-based pre-catalysts exhibit improved OER activity and long-term durability.This study provides a novel perspective for understanding the role of Fe in the OER process.展开更多
肺4D-CT在肺癌放射治疗中发挥着重要的作用,但肺4D-CT数据层间的分辨率低,导致每个相位3D数据的肺冠矢状面均为低分辨率图像。本研究提出一种基于运动估计的超分辨率重建技术,以提高3D数据的冠矢状面图像分辨率。首先,分析图像退化模型...肺4D-CT在肺癌放射治疗中发挥着重要的作用,但肺4D-CT数据层间的分辨率低,导致每个相位3D数据的肺冠矢状面均为低分辨率图像。本研究提出一种基于运动估计的超分辨率重建技术,以提高3D数据的冠矢状面图像分辨率。首先,分析图像退化模型;然后,采用基于完全搜索块匹配的运动估计法,估计出不同"帧"肺冠矢状面图像之间的运动场;最后,以此运动场为基础,采用迭代反投影法(IBP),重建高分辨率的肺部冠矢状面图像。使用一个公共可用的数据集来评价所提出的算法,该数据集由10组肺4D-CT数据组成,每组数据包含10个相位。在每组图像中,选取不同相位的冠矢状面图像进行实验。结果表明,与传统的插值方法(如最近邻插值、双线性插值法)相比,图像边缘宽度均显著降低(最近邻插值9.93±0.59,双线性插值8.04±0.69,新算法5.41±0.60,P<0.001);较双线性插值,图像平均梯度显著提高(5.41±0.59 vs 7.49±0.75,P<0.001),新方法不仅能获得视觉上清晰的图像,而且量化评价指标也有明显提高。主观和客观实验结果表明,所提出的新方法能有效提高肺4D-CT冠矢状面图像的分辨率。展开更多
基金Guangzhou Municipal Medicine &Health ProgramGrant number:2006-YB-177+1 种基金Guangdong Province Medicine Scientific Research ProgramGrant number:A2007290
文摘Objective:To investigate the feasibility of a 4D-CT reconstruction method based on the similarity principle of spatial adjacent images and mutual information measure. Methods:A motor driven sinusoidal motion platform made in house was used to create one-dimensional periodical motion that was along the longitudinal axis of the CT couch. The amplitude of sinusoidal motion was set to an amplitude of ±1 cm. The period of the motion was adjustable and set to 3.5 s. Phantom objects of two eggs were placed in a Styrofoam block, which in turn were placed on the motion platform. These objects were used to simulate volumes of interest undergoing ideal periodic motion. CT data of static phantom were acquired using a multi-slice general electric (GE) LightSpeed 16-slice CT scanner in an axial mode. And the CT data of periodical motion phantom were acquired in an axial and cine-mode scan. A software program was developed by using VC++ and VTK software tools to resort the CT data and reconstruct the 4D-CT. Then all of the CT data with same phase were sorted by the program into the same series based on the similarity principle of spatial adjacent images and mutual information measure among them, and 3D reconstruction of different phase CT data were completed by using the software. Results:All of the CT data were sorted accurately into different series based on the similarity principle of spatial adjacent images and mutual information measures among them. Compared with the unsorted CT data, the motion artifacts in the 3D reconstruction of sorted CT data were reduced significantly, and all of the sorted CT series result in a 4D-CT that reflected the characteristic of the periodical motion phantom. Conclusion:Time-resolved 4D-CT reconstruction can be implemented with any general multi-slice CT scanners based on the similarity principle of spatial adjacent images and mutual information measure.The process of the 4D-CT data acquisition and reconstruction were not restricted to the hardware or software of the CT scanner and has the feasibility ,which extensive applicability.
基金financially supported by the Scientific and Technological Development Program of Jilin Province(20220201138GX)the support of the National Key R&D Program of China(No.2022YFA1503801)+1 种基金CAS Project for Young Scientists in Basic Research(No.YSBR-022)the Young Cross Team Project of CAS(No.JCTD-2021-14)。
文摘Ni-Fe-based catalysts are considered to be among the most active catalysts for the oxygen evolution reaction(OER)under alkaline conditions,with Fe playing a crucial role.However,Fe leaching occurs during the reaction due to thermodynamic instability,which has resulted in conflicting reports within the literature regarding its role.To clarify this point,we propose a strategy consisting of modulating the electronic orbital occupancy to suppress the extensive loss of Fe atoms during the OER process.Theoretical calculations,in-situ X-ray photoelectron spectroscopy,molecular dynamics simulations,and a series of characterization showed that the stable presence of Fe not only accelerates the electron transfer process but also optimizes the reaction barriers of the oxygen evolution intermediates,promoting the phase transition of Fe_(5)Ni_(4)S_(8)to highly active catalytic species.The modulated Fe_(5)Ni_(4)S_(8)-based pre-catalysts exhibit improved OER activity and long-term durability.This study provides a novel perspective for understanding the role of Fe in the OER process.
文摘肺4D-CT在肺癌放射治疗中发挥着重要的作用,但肺4D-CT数据层间的分辨率低,导致每个相位3D数据的肺冠矢状面均为低分辨率图像。本研究提出一种基于运动估计的超分辨率重建技术,以提高3D数据的冠矢状面图像分辨率。首先,分析图像退化模型;然后,采用基于完全搜索块匹配的运动估计法,估计出不同"帧"肺冠矢状面图像之间的运动场;最后,以此运动场为基础,采用迭代反投影法(IBP),重建高分辨率的肺部冠矢状面图像。使用一个公共可用的数据集来评价所提出的算法,该数据集由10组肺4D-CT数据组成,每组数据包含10个相位。在每组图像中,选取不同相位的冠矢状面图像进行实验。结果表明,与传统的插值方法(如最近邻插值、双线性插值法)相比,图像边缘宽度均显著降低(最近邻插值9.93±0.59,双线性插值8.04±0.69,新算法5.41±0.60,P<0.001);较双线性插值,图像平均梯度显著提高(5.41±0.59 vs 7.49±0.75,P<0.001),新方法不仅能获得视觉上清晰的图像,而且量化评价指标也有明显提高。主观和客观实验结果表明,所提出的新方法能有效提高肺4D-CT冠矢状面图像的分辨率。
