Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based ...Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.展开更多
Introduction: Radiotherapy (RT) is a vital cancer treatment modality for both curative and palliative purposes. Nepal is a developing country with a population of around 30 million people. Cancer affects 100 - 120 peo...Introduction: Radiotherapy (RT) is a vital cancer treatment modality for both curative and palliative purposes. Nepal is a developing country with a population of around 30 million people. Cancer affects 100 - 120 people out of every 100,000, and the figure is increasing. The number of radiation facility machines in the country is still countable in fingers. Purbanchal Cancer Hospital, Nepal is the first comprehensive cancer facility capable of performing stereotactic radiosurgery (SRS). Our facility has cutting-edge Varian Truebeam Linear Accelerators with millennium MLC, which makes SRS and SRT’S for intracranial lesions such as small benign and malignant tumors much easier. In addition to SRS, we are the pioneers of SBRT for lung using 4DCT, interstitial & intraluminal brachytherapy, RPM Gated & DIBH modalities in Nepal. Methods & Materials: The purpose of this study is to share our experience in establishing an SRS facility in the country, which includes training the RT team on the importance of process accuracy, patient selection, patient assessment, mould preparation, and describing image data acquisition, target, and organ at risk delineation on CT and MRI images, treatment planning process, and quality assurance. Results & Discussion: The plans for all SRS and SRT cases are based on target coverage, OAR sparing, hotspot inside the target, conformity index, heterogeneity index, and dose fall off. To select the final plan, we used strict passing criteria such as a conformity index Paddick (CIPaddick) more than 0.85, a falloff between 100% and 50% of less than 5.5 mm (maximum 6 mm in irregular targets), and a hotspot inside the target between 115 to 140 percent, as per clinical standards. In addition, we determined the CILomax and CIRTOG for each case. Passing criteria for verification plans are set as minimum of 95% for a 2% percentage dose difference (% DD) and a 2-mm distance to an agreement (DTA). We also gathered demographic data from patients treated in the first year, such as diagnosis, lesion size, dose fraction, heterogeneity index (HI), conformity index (CI) and gamma index. SRS/SRT treatment was successfully implemented, and over 40 patients were treated with positive clinical outcomes. Conclusion: SRS now has a wider range of alternatives, thanks to technology advancements in recent years. SRS’s dosimetric advantages have steadily been extended to extracranial locations. Purbanchal Cancer Hospital, Birtamode, Nepal established a comprehensive cancer facility with qualified workforce with the goal of providing high-quality treatment to the people of Nepal.展开更多
目的研究一种表征可吸收胶原蛋白材料微观形貌的方法,并分析其孔隙率和孔径。方法利用场发射扫描电子显微镜(Scanning Electron Microscope,SEM),在不同的加速电压下对未喷金样品和喷金样品进行拍摄,使用Image J软件对所得的SEM图像的...目的研究一种表征可吸收胶原蛋白材料微观形貌的方法,并分析其孔隙率和孔径。方法利用场发射扫描电子显微镜(Scanning Electron Microscope,SEM),在不同的加速电压下对未喷金样品和喷金样品进行拍摄,使用Image J软件对所得的SEM图像的孔隙率和孔径进行分析,并对结果的有效性进行验证。结果样品未喷金时使用低倍加速电压可获得清晰的SEM图像;样品喷金后其耐受电压能力明显提高,即使在较高的加速电压下依然能获得清晰的SEM图像。使用Image J软件可对拍摄的SEM图像的孔径和孔隙率进行分析,其中,平均孔隙率为50.9%,平均孔径为11.9μm;孔隙率离散系数为8.6%,孔径离散系数6.7%。结论场发射SEM结合Image J软件是一种表征可吸收胶原蛋白材料孔结构的有效方法,可解决相关标准中方法缺失的问题。展开更多
The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99（1） eV for LaO, 1.00（1） eV for CeO, 1...The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99（1） eV for LaO, 1.00（1） eV for CeO, 1.00（1） eV for PrO, and 1.01（1） eV for NdO, respectively. Density functional calculations and natural atomic orbital analyses show that the 4f electrons tend to be localized and suffer little from the charge states of the molecules. The photodetached electron mainly originates from the 6s orbital of the metals. The ligand field theory with the δ=2 assumption is still an effective method to analyze the ground states of the neutral and anionic lanthanide monoxides.展开更多
电子轰击型有源像素传感器(electron bombarded active pixel sensor,EBAPS)具有高增益、快响应、低功耗和低成本等优点,研究EBAPS已成为微光夜视成像技术的一个重要发展方向。国内相关机构在电路设计时,对于EBAPS成像电路中所涉及到的...电子轰击型有源像素传感器(electron bombarded active pixel sensor,EBAPS)具有高增益、快响应、低功耗和低成本等优点,研究EBAPS已成为微光夜视成像技术的一个重要发展方向。国内相关机构在电路设计时,对于EBAPS成像电路中所涉及到的芯片主要还是依赖于进口,为加快EBAPS器件成像电路的国产化进程,研制了一套基于EBAPS的全国产成像电路评估板。该电路以国产复旦微FMK50t系列的FPGA芯片为主控芯片,通过设计CMOS(complementary metal oxide semiconductor)驱动模块、数据处理模块、Cameralink显示模块等,分别完成对EBAPS器件的驱动、数字图像处理和实时显示等功能。实验结果表明:在轰击高压为负1 500 V的情况下,该国产EBAPS相机的最低探测照度可达到10-3lx量级。展开更多
扫描透射电子显微镜(Scanning transmission electron microscopy,STEM)目前已经达到了原子级分辨率,并且由于其具有灵活的多通道成像能力以及强大的与谱学分析相结合的特点,因此在材料科学、生命科学等领域展现出强大的微尺度表征能力...扫描透射电子显微镜(Scanning transmission electron microscopy,STEM)目前已经达到了原子级分辨率,并且由于其具有灵活的多通道成像能力以及强大的与谱学分析相结合的特点,因此在材料科学、生命科学等领域展现出强大的微尺度表征能力。但传统STEM的探测器受单像素积分式探测机制的限制,使其只能收集特定角度的散射电子,这导致不仅丢失了散射电子的角分辨信息,还降低了入射电子的剂量效率,因此迫切需要发展全新成像技术来实现高通量、高电子剂量效率成像。近年来,电子探测技术和分区或像素化探测器的研发联合计算机运算、存储能力的大幅提高,推动了四维扫描透射电子显微镜技术(Four-dimensional scanning transmission electron microscopy,4D-STEM)的蓬勃发展,并为最大化、最高效挖掘散射电子信息带来希望。在采集4D-STEM数据时,会聚电子束在样品平面上进行二维扫描,与此同时使用一块具有高帧速、高动态范围以及高信噪比的像素化阵列式探测器在远场收集二维的衍射数据。因为这些衍射数据是角度解析的,所以既可以用来进行常规的STEM成像,也可以用来实现前沿的相位衬度成像。例如利用电子叠层重构(Ptychography)技术通过在不同空间位置测量的一系列衍射花样来重建样品物函数。此外,4D-STEM技术还可以被进一步挖掘从而获得更多关于材料内部结构的信息,这为材料的多尺度表征带来机会。本文从4D-STEM技术原理介绍开始,总结了4D-STEM技术从材料微观结构到物性分析方面的一系列应用。具体而言,内容包含了虚拟探测器成像、微区电磁场测量、微区晶体取向测量、微区应变分布测量以及材料局域厚度测量等材料微尺度表征方面的原理和应用。除此之外,利用4D-STEM数据实现的电子叠层重构成像技术因为具有较高的散射电子利用效率,所以在低电子剂量领域展现出极大的应用潜力,因此本文还对4D-STEM技术在低电子剂量领域的应用进行了探讨与展望。总而言之,随着电子探测器以及4D-STEM数据后处理分析软件的快速发展,相信新颖的4D-STEM技术最终将彻底取代传统的扫描透射电子显微镜。展开更多
Objective To test a quality assurance(QA)DVS solution-DVS based on a linac electronic field imaging device(EPID)and evaluate its accuracy and ease of use.Methods All of the QA items that do not require the dedicated Q...Objective To test a quality assurance(QA)DVS solution-DVS based on a linac electronic field imaging device(EPID)and evaluate its accuracy and ease of use.Methods All of the QA items that do not require the dedicated QA phantom in the DVS solution were tested.Test methods were chosen based on the test items:for the collimator rotation center,the coincidence of the radiation and mechanical,mechanical flatness/symmetry and MLC transmission were compared with the existing QA solution;for the leaf position accuracy and repeatability,the original preset beam fields and fields adjusted by 1 mm were compared.Results The collimator rotation center by the DVS solution is similar to the existing solution.For coincidence of radiation and mechanical,the DVS solution provides more data,including 3D distance.For the flatness/symmetry property,the DVS solution can display more graphics,but the overall data is less than the ion-chamber matrix solution.The DVS solution can directly obtain the MLC transmission value and quickly and intuitively measure the position accuracy of the MLC.However,the repeatability is slightly worse.Conclusion The DVS solution can improve the QA work efficiency and reduce workload,and there are more opportunities for improvement.展开更多
基金supported by the National Natural Science Foundation of China(6110118561302145)
文摘Digital image stabilization technique plays important roles in video surveillance and object acquisition.Many useful electronic image stabilization algorithms have been studied.A real-time algorithm is proposed based on field image gray projection which enables the regional odd and even field image to be projected into x and y directions and thus to get the regional gray projection curves in x and y directions,respectively.For the odd field image channel,motion parameters can be estimated via iterative minimum absolute difference based on two successive field image regional gray projection curves.Then motion compensations can be obtained after using the Kalman filter method.Finally,the odd field image is adjusted according to the compensations.In the mean time,motion compensation is applied to the even field image channel with the odd field image gray projection curves of the current frame.By minimizing absolute difference between odd and even field image gray projection curves of the current frame,the inter-field motion parameters can be estimated.Therefore,the even field image can be adjusted by combining the inter-field motion parameters and the odd field compensations.Finally,the stabilized image sequence can be obtained by synthesizing the adjusted odd and even field images.Experimental results show that the proposed algorithm can run in real-time and have a good stabilization performance.In addition,image blurring can be improved.
文摘Introduction: Radiotherapy (RT) is a vital cancer treatment modality for both curative and palliative purposes. Nepal is a developing country with a population of around 30 million people. Cancer affects 100 - 120 people out of every 100,000, and the figure is increasing. The number of radiation facility machines in the country is still countable in fingers. Purbanchal Cancer Hospital, Nepal is the first comprehensive cancer facility capable of performing stereotactic radiosurgery (SRS). Our facility has cutting-edge Varian Truebeam Linear Accelerators with millennium MLC, which makes SRS and SRT’S for intracranial lesions such as small benign and malignant tumors much easier. In addition to SRS, we are the pioneers of SBRT for lung using 4DCT, interstitial & intraluminal brachytherapy, RPM Gated & DIBH modalities in Nepal. Methods & Materials: The purpose of this study is to share our experience in establishing an SRS facility in the country, which includes training the RT team on the importance of process accuracy, patient selection, patient assessment, mould preparation, and describing image data acquisition, target, and organ at risk delineation on CT and MRI images, treatment planning process, and quality assurance. Results & Discussion: The plans for all SRS and SRT cases are based on target coverage, OAR sparing, hotspot inside the target, conformity index, heterogeneity index, and dose fall off. To select the final plan, we used strict passing criteria such as a conformity index Paddick (CIPaddick) more than 0.85, a falloff between 100% and 50% of less than 5.5 mm (maximum 6 mm in irregular targets), and a hotspot inside the target between 115 to 140 percent, as per clinical standards. In addition, we determined the CILomax and CIRTOG for each case. Passing criteria for verification plans are set as minimum of 95% for a 2% percentage dose difference (% DD) and a 2-mm distance to an agreement (DTA). We also gathered demographic data from patients treated in the first year, such as diagnosis, lesion size, dose fraction, heterogeneity index (HI), conformity index (CI) and gamma index. SRS/SRT treatment was successfully implemented, and over 40 patients were treated with positive clinical outcomes. Conclusion: SRS now has a wider range of alternatives, thanks to technology advancements in recent years. SRS’s dosimetric advantages have steadily been extended to extracranial locations. Purbanchal Cancer Hospital, Birtamode, Nepal established a comprehensive cancer facility with qualified workforce with the goal of providing high-quality treatment to the people of Nepal.
基金This work was supported by the National Natural Science Foundation of China （No.20933003） and the National Basic Research Program of China （No.2010CB732306）.
文摘The photoelectron imagings of LaO-, CeO-, PRO-, and NdO- at 1064 nm are reported. The well resolved photoelectron spectra allow the electron affinities to be determined as 0.99（1） eV for LaO, 1.00（1） eV for CeO, 1.00（1） eV for PrO, and 1.01（1） eV for NdO, respectively. Density functional calculations and natural atomic orbital analyses show that the 4f electrons tend to be localized and suffer little from the charge states of the molecules. The photodetached electron mainly originates from the 6s orbital of the metals. The ligand field theory with the δ=2 assumption is still an effective method to analyze the ground states of the neutral and anionic lanthanide monoxides.
文摘电子轰击型有源像素传感器(electron bombarded active pixel sensor,EBAPS)具有高增益、快响应、低功耗和低成本等优点,研究EBAPS已成为微光夜视成像技术的一个重要发展方向。国内相关机构在电路设计时,对于EBAPS成像电路中所涉及到的芯片主要还是依赖于进口,为加快EBAPS器件成像电路的国产化进程,研制了一套基于EBAPS的全国产成像电路评估板。该电路以国产复旦微FMK50t系列的FPGA芯片为主控芯片,通过设计CMOS(complementary metal oxide semiconductor)驱动模块、数据处理模块、Cameralink显示模块等,分别完成对EBAPS器件的驱动、数字图像处理和实时显示等功能。实验结果表明:在轰击高压为负1 500 V的情况下,该国产EBAPS相机的最低探测照度可达到10-3lx量级。
文摘扫描透射电子显微镜(Scanning transmission electron microscopy,STEM)目前已经达到了原子级分辨率,并且由于其具有灵活的多通道成像能力以及强大的与谱学分析相结合的特点,因此在材料科学、生命科学等领域展现出强大的微尺度表征能力。但传统STEM的探测器受单像素积分式探测机制的限制,使其只能收集特定角度的散射电子,这导致不仅丢失了散射电子的角分辨信息,还降低了入射电子的剂量效率,因此迫切需要发展全新成像技术来实现高通量、高电子剂量效率成像。近年来,电子探测技术和分区或像素化探测器的研发联合计算机运算、存储能力的大幅提高,推动了四维扫描透射电子显微镜技术(Four-dimensional scanning transmission electron microscopy,4D-STEM)的蓬勃发展,并为最大化、最高效挖掘散射电子信息带来希望。在采集4D-STEM数据时,会聚电子束在样品平面上进行二维扫描,与此同时使用一块具有高帧速、高动态范围以及高信噪比的像素化阵列式探测器在远场收集二维的衍射数据。因为这些衍射数据是角度解析的,所以既可以用来进行常规的STEM成像,也可以用来实现前沿的相位衬度成像。例如利用电子叠层重构(Ptychography)技术通过在不同空间位置测量的一系列衍射花样来重建样品物函数。此外,4D-STEM技术还可以被进一步挖掘从而获得更多关于材料内部结构的信息,这为材料的多尺度表征带来机会。本文从4D-STEM技术原理介绍开始,总结了4D-STEM技术从材料微观结构到物性分析方面的一系列应用。具体而言,内容包含了虚拟探测器成像、微区电磁场测量、微区晶体取向测量、微区应变分布测量以及材料局域厚度测量等材料微尺度表征方面的原理和应用。除此之外,利用4D-STEM数据实现的电子叠层重构成像技术因为具有较高的散射电子利用效率,所以在低电子剂量领域展现出极大的应用潜力,因此本文还对4D-STEM技术在低电子剂量领域的应用进行了探讨与展望。总而言之,随着电子探测器以及4D-STEM数据后处理分析软件的快速发展,相信新颖的4D-STEM技术最终将彻底取代传统的扫描透射电子显微镜。
文摘Objective To test a quality assurance(QA)DVS solution-DVS based on a linac electronic field imaging device(EPID)and evaluate its accuracy and ease of use.Methods All of the QA items that do not require the dedicated QA phantom in the DVS solution were tested.Test methods were chosen based on the test items:for the collimator rotation center,the coincidence of the radiation and mechanical,mechanical flatness/symmetry and MLC transmission were compared with the existing QA solution;for the leaf position accuracy and repeatability,the original preset beam fields and fields adjusted by 1 mm were compared.Results The collimator rotation center by the DVS solution is similar to the existing solution.For coincidence of radiation and mechanical,the DVS solution provides more data,including 3D distance.For the flatness/symmetry property,the DVS solution can display more graphics,but the overall data is less than the ion-chamber matrix solution.The DVS solution can directly obtain the MLC transmission value and quickly and intuitively measure the position accuracy of the MLC.However,the repeatability is slightly worse.Conclusion The DVS solution can improve the QA work efficiency and reduce workload,and there are more opportunities for improvement.
