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A high-resolution small animal SPECT system developed at Tsinghua

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Nuclear Science and Techniques 2011年第6期22卷 344-348页

作者： DAI Tiantian MATianyu liu Hui CUI Junjian WEI Qingyang liu yaqiang WANG Shi Key Laboratory of Particle&Radiation Imaging Ministry of EducationDepartment of Engineering PhysicsTsinghua UniversityBeijing 10084China

An SPECT system dedicated to small animal imaging shall be of a millimeter spatial resolution or even *** study was aimed at achieving 0.5-mm spatial resolution for a small animal SPECT system at low *** was developed from a single-head clinical SPECT scanner,with a seven-pinhole collimator and a four-degree-offreedom motion control *** key techniques were developed,including high-resolution image reconstruction algorithm,high accuracy geometrical calibration method,and optimized system matrix derivation *** system matrix was derived from Monte-Carlo simulation and de-noised by fitting each point spread function to a two dimensional Gaussian *** of point source and ultra micro hot rod phantom were *** a spatial resolution of 0.5-0.6 mm,this system provides a practical way for low-cost high-resolution animal imaging on a clinic SPECT system.

关键词：高分辨率图像重建 ECT系统小动物 SP 清华大学开发空间分辨率高斯函数拟合

PET image reconstruction with rotationally symmetric polygonal pixel grid based highly compressible system matrix

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Nuclear Science and Techniques 2013年第3期24卷 6-17页

作者： YU Yunhan XIA Yan CHEN Jing HONG Baoyu liu yaqiang WANG Shi MA Tianyu Key Laboratory of Particle & Radiation Imaging (Tsinghua University) Ministry of Education Department of Engineering PhysicsTsinghua University National Institute of Metrology

To achieve a maximum compression of system matrix in positron emission tomography (PET) image reconstruction, we proposed a polygonal image pixel division strategy in accordance with rotationally symmetric PET geometry. Geometrical definition and indexing rule for polygonal pixels were established. Image conversion from polygonal pixel structure to conventional rectangular pixel structure was implemented using a conversion matrix. A set of test images were analytically defined in polygonal pixel structure, converted to conventional rectangular pixel based images, and correctly displayed which verified the correctness of the image definition, conversion description and conversion of polygonal pixel structure. A compressed system matrix for PET image recon was generated by tap model and tested by forward-projecting three different distributions of radioactive sources to the sinogram domain and comparing them with theoretical predictions. On a practical small animal PET scanner, a compress ratio of 12.6:1 of the system matrix size was achieved with the polygonal pixel structure, comparing with the conventional rectangular pixel based tap-mode one. OS-EM iterative image reconstruction algorithms with the polygonal and conventional Cartesian pixel grid were developed. A hot rod phantom was detected and reconstructed based on these two grids with reasonable time cost. Image resolution of reconstructed images was both 1.35 mm. We conclude that it is feasible to reconstruct and display images in a polygonal image pixel structure based on a compressed system matrix in PET image reconstruction.

关键词：图像重建图像像素转换矩阵压缩系统多边形旋转对称 PET 可压缩

Imaging performance evaluation in depth-of-interaction PET with a new method of sinogram generation:A Monte Carlo simulation study

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Nuclear Science and Techniques 2011年第3期22卷 144-150页

作者： XIA Yan MA Tianyu liu yaqiang SUN Xishan WANG Shi SHAO Yiping Departmento lEngineeringPhysics.KeyLaboratoryofParticle&RadiationImagingrTsinghuaUniversityMinistryoJEducationBeo'ing100084China OepartmentofImagingPhysics.UniversityofTexasMD.AndersonCancerCente~Houston.Texas77030.USA

In conventional PET systems,the parallax error degrades image resolution and causes image *** remedy this,a PET ring diameter has to be much larger than the required size of field of view(FOV),and therefore the cost goes *** of depth-of-interaction(DOI)information is effective to reduce the parallax error and improve the image *** study is aimed at developing a practical method to incorporate DOI information in PET sinogram generation and image reconstruction processes and evaluate its efficacy through Monte Carlo *** animal PET system with 30-mm long LSO crystals and 2-mm DOI measurement accuracy was simulated and list-mode PET data were collected.A sinogram generation method was proposed to bin each coincidence event to the correct LOR location according to both incident crystal indices and DOI positions of the two annihilation *** sinograms were reconstructed with an iterative OSMAPEM(ordered subset maximum a posteriori expectation maximization)*** phantoms(a rod source phantom and a Derenzo phantom)were simulated,and the benefits of DOI were investigated in terms of reconstructed source diameter(FWHM)and source positioning *** results demonstrate that the proposed method works well to incorporate DOI information in data processing,which not only overcomes the image distortion problem but also significantly improves image resolution and resolution uniformity and results in satisfactory image quality.

关键词：蒙特卡罗模拟 PET 性能评价图像分辨率 LSO晶体成像图像失真图像质量

Hydrothermal synthesis of vanadium oxide nanotubes by a facile route

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Rare Metals 2006年第z1期25卷 88-93页

作者： HUANG Chunming liu Xueqin KONG Lingbin ZHOU Haijia liu yaqiang QIU Jiawen WANG Yinyue Department of Physics Lanzhou University Lanzhou 730000 China Department of Physics Lanzhou University Lanzhou 730000 China Lanzhou Institute of Physics Lanzhou 730000 China State Key Laboratory of Gansu Advanced Non-Ferrous Metal Materials Lanzhou University of Technology Lanzhou 730050 China Department of Physics Lanzhou University Lanzhou 730000 China Department of Physics Lanzhou University Lanzhou 730000 China Lanzhou Institute of Physics Lanzhou 730000 China Department of Physics Lanzhou University Lanzhou 730000 China

Vanadium oxide nanotubes were synthesized by hydrothermal treatment from V2O5·nH2O sols as precursor and dodecylamine as structure-directing template. The morphology and structure of the nanotubes were characterized by SEM, TEM, XRD, TG-DTA and FTIR. The experimental results reveal that the duration of the hydrothermal treatment is of importance for obtaining VOx-NTs which have a layered structure. TG-DTA study indicates that V5+ cations in nanotubes are partially reduced to V4+ cations. The results from FTIR spectra indicate the difference in V-O vibrations between before and after hydrothermal treatment. From the results, it suggests that during hydrothermal treatment, the rearrangement of the vanadium oxide structure leads to the formation of VOx nanotubes from lamellar structure because of the presence of V4+ species.

关键词： vanadium oxide nanotubes hydrothermal synthesis V2O5 sols

Influence factors of two dimensional position map on photomultiplier detector block designed by quadrant sharing technique

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Nuclear Science and Techniques 2011年第4期22卷 224-229页

作者： WEI Qingyang WANG Shi Ma Tianyu MA Fei DAI Tiantian XU Tianpeng WU Zhaoxia JIN Yongjie liu yaqiang Key Laboratory of Particle & Radiation Imaging (Tsinghua University) Ministry of Education Department of Engineering Physics Tsinghua University Beijing 100084 China

The position decoding accuracy and the spatial resolution of positron emission tomography detectors are greatly influenced by the performance of the two-dimensional position map,including the gain uniformity of photomultiplier tube (PMT),the baseline offset of the PMT signals and the accuracy of analogue to digital converter (ADC).In this work,a PMT-quadrant sharing detector was *** data acquisition platforms are employed to conduct the influence factors on the two-dimensional position map performances,one was that the waveforms of the PMT signals were scanned by the sequence acquisition mode based on the oscilloscope of LeCroy waveRunner 204MXi-A,and another was a self-developed high speed ADC data acquisition *** show that the event decoding positions were concentrated on the PMT with higher gain,the position map was distorted at the baseline offset of signal,and the cross-line artifacts were caused by the insufficient ADC sampling bit for a larger size position *** the parameters need be adjusted properly to stabilize a real system,and the flexible oscilloscope platform can be used to design the detector block and the other platform with high ADC ***,the electrical circuit with a proper ADC accuracy adjusts the PMT gains and baseline offsets.

关键词：光电倍增管三维位置影响因素共享技术地图设计正电子发射断层扫描象限

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纳米V_2O_5薄膜的制备与特性

稀有金属材料与工程 2009年第4期38卷 691-695页

作者：刘亚强刘雪芹商丘师范学院河南商丘476000 兰州大学甘肃兰州730000

采用溶胶-凝胶法在Si和普通玻璃基底上制备V2O5纳米薄膜。在空气中对样品进行不同温度的退火处理。利用X射线衍射、扫描电子显微镜和分光光度计对制备的V2O5薄膜的结构、形貌和光学特性进行研究。XRD和SEM研究结果表明:可以通过升高退... 详细信息

采用溶胶-凝胶法在Si和普通玻璃基底上制备V2O5纳米薄膜。在空气中对样品进行不同温度的退火处理。利用X射线衍射、扫描电子显微镜和分光光度计对制备的V2O5薄膜的结构、形貌和光学特性进行研究。XRD和SEM研究结果表明:可以通过升高退火温度来提高薄膜的结晶程度、颗粒尺寸及其均匀程度,并增强V2O5的择优取向性。透射谱和吸收谱的研究结果表明:随着退火温度的升高,V2O5薄膜的吸收边缘发生红移,光学带隙逐渐变窄。

关键词： V2O5薄膜溶胶-凝胶法微结构光学特性

碘-131 SPECT平片成像伪影校正算法

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清华大学学报（自然科学版） 2023年第5期63卷 802-810页

作者：程李刘帆高丽蕾刘辉刘亚强清华大学工程物理系北京100084 北京永新医疗设备有限公司北京102206

碘-131单光子发射计算机断层扫描(single photon emission computed tomography,SPECT)平片成像已广泛应用于甲状腺癌的临床诊断和治疗评估中。由于碘-131发射的Gamma光子能量较高,穿透SPECT准直器隔壁的概率较大,易导致最终图像上出现... 详细信息

碘-131单光子发射计算机断层扫描(single photon emission computed tomography,SPECT)平片成像已广泛应用于甲状腺癌的临床诊断和治疗评估中。由于碘-131发射的Gamma光子能量较高,穿透SPECT准直器隔壁的概率较大,易导致最终图像上出现放射状伪影。为解决该问题,该文提出了一种点扩展函数解卷积结合先验正则化的方法,并基于Monte Carlo模拟和临床数据对该方法进行了验证。模拟数据表明该算法具有很好的单调收敛性。当采用127×127的点扩展函数(像素大小2.2 mm×2.2mm),设置正则化参数为0.01时,模拟数据、临床点源数据和人体数据的放射状伪影区域计数值可分别降低至原始值的4%、35%和28%,同时还可以维持背景区域较低的噪声水平。研究结果表明:该文算法可以有效解决碘-131 SPECT平片成像中的放射状伪影问题,从而提高临床诊断精度。

关键词：碘-131 单光子发射计算机断层扫描放射状伪影解卷积先验正则化

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H_2FCS单分子分解反应的直接动力学研究

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化学学报 2009年第22期67卷 2541-2548页

作者：刘艳任宏江刘亚强王渭娜渭南师范学院化学化工系渭南714000 西安文理学院化学系西安710065 陕西师范大学化学与材料科学学院西安710062

采用量子化学QCISD(T)/6-311++G(d,p)//B3LYP/6-311+G(d,p)方法研究了H2FCS单分子分解反应的微观动力学性质,构建了反应势能剖面.利用经典过渡态理论(TST)与变分过渡态理论(CVT)并结合小曲率隧道效应模型(SCT),分别计算了在200～3000K... 详细信息

采用量子化学QCISD(T)/6-311++G(d,p)//B3LYP/6-311+G(d,p)方法研究了H2FCS单分子分解反应的微观动力学性质,构建了反应势能剖面.利用经典过渡态理论(TST)与变分过渡态理论(CVT)并结合小曲率隧道效应模型(SCT),分别计算了在200～3000K温度范围内的速率常数kTST,kCVT和kCVT/SCT.计算结果表明,H2FCS可经过不同的反应通道生成10种小分子产物,脱H反应和HF消去反应为标题反应的主反应通道,其中HF消去反应产物HCS可由两条反应通道生成.在200～3000K温度区间内得到三条反应通道的表观反应速率常数三参数表达式分别为kPath(1)CVT/SCT=3.6×10-41T12.8exp(11597.7/T)cm3·molecule-1·s-1,kPCaVthT(3/S)CT=3.6×10-15T5.52exp(19769.4/T)cm3?molecule-1·s-1和Path(4)CVT/SCT=1.5×10-3T2.03exp(21821.6/T)cm3·molecule-1·s-1.速率常数计算结果显示,量子力学隧道效应在低温区间对反应速率常数的影响显著,而变分效应在计算温度范围内可以忽略.

关键词： H2FCS 密度泛函理论反应机理速率常数

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国产SPECT/CT系统的定量性能研究

清华大学学报（自然科学版） 2024年第8期64卷 1509-1515页

作者：江年铭刘帆程李高丽蕾刘辉刘亚强清华大学工程物理系北京100084 北京永新医疗设备有限公司北京102206

通过与国际先进的单光子发射计算机断层扫描/电子计算机断层扫描(single-photon emission computed tomography/computed tomography, SPECT/CT)成像系统GE Discovery NM/CT 670对比,评估了国产SPECT/CT成像系统Insight NM/CT Pro定量精度,以实现定量成像。该国产成像系统由北京永新医疗设备有限公司研制。该文通过精确定量标定Insight NM/CT Pro,结合中国医药行业推荐标准YY/T 1546—2017《用于SPECT成像CT衰减校正的试验方法》和美国电气制造商协会(National Electrical Manufactures Association, NEMA)标准NEMA NU 1—2018《Gamma相机的性能测量》的相关要求,采用低能高分(low energy high resolution, LEHR)准直器评估放射性核素锝-99 m(99mTc)成像的主要性能指标,并与GE Discovery NM/CT 670进行对比。首先,使用衰减精度模型测试空气、水和骨3种不同插件的衰减误差;其次,使用NEMA NU 1—2018体模测试2个成像系统的定量精度。结果表明:Insight NM/CT Pro获得的重建图像中空气、水和骨的衰减误差依次为7.84%、 8.38%和4.66%;直径为13、 17、 22和28 mm的“热区”小球的定量恢复系数分别为38.22%、 50.98%、 66.55%和71.32%,背景浓度偏差为7.95%。国产Insight NM/CT Pro成像系统获得的重建图像质量和定量精度与GE Discovery NM/CT 670成像系统效果相当,证实了该系统定量可靠。

关键词： SPECT/CT 衰减校正模体评估定量精度