Si（Li）电子谱仪的研制

研制了“无窗”的Ｓｉ（Ｌｉ）电子谱仪，测量了＾２０７Ｂｉ的内转换电子能谱，对能量９７５．６２ｋｅＶ的电子取得了２．０７ｋｅＶ的能量分辨率。     

SPECT脑血流灌注显像应用于脑血管疾病

７０例脑血管疾病患者（脑梗塞、ＴＩＡ、ＶＢＩ）行＾９９ｍＴｃ－ＥＣＤ ＳＰＥＣＴ脑血流灌注显像，并与ＣＴ、ＭＲＩ对照，结果ＳＥＰＣＴ诊断脑血管病的阳性率为９０％。ＣＴ为８８．２％（４５／５１），ＭＲＩ为９０％（２７／３１）。脑梗塞５５例中５１例ｒＣＢＦ图像上出现血流灌注减低区，４例发现交叉性小脑神经机能失联络证。诊断ＴＩＡ、ＶＢＩ的阳性率为７５％。ＳＰＥＣＴｒＣＢＦ显像发现病灶较ＣＴ、ＭＲＩ多；可     

大面积Si（Li）探测器

测量了不同温度条件下面积为４９ｍｍ×４９ｍｍ、厚３．５ｍｍ的Ｓｉ（Ｌｉ）探测器的Ｉ－Ｖ特性。Ｓｉ（Ｌｉ）－Ｅ－１和Ｅ－２探测器对＾２３８Ｐｕ５．４９９ＭｅＶ α粒子的能量分辨率例如为５４．４ｋｅＶ和５７．０９ｋｅＶ。     

C、Co及C+Co双注入对高速钢机械性能影响的研究

采用ＭＥＶＶＡ源离子注入机对高速工具钢进行了Ｃ,Ｃｏ及Ｃ＋Ｃｏ注入,并做了硬度,摩擦系数测量和磨损实验,Ｃ离子注入剂量３×１０＾１７ｃｍ＾－２能量６０ｋｅＶ,Ｃｏ离子注入剂量为２×１０＾１７,４×１０＾１７,６×１０＾１７ｃｎ＾－２能量１０２ｋｅＶ。结果表明,不同元素,不同剂量的离子注入均能有效地改善ＨＳＳ的硬度和摩擦磨损特性,从而极大延长ＨＳＳ的工作寿命,且随着注入剂量的增加,改善的效果有所增强     

45例^134I—MIBG肾上腺髓质显像临床应用

用＾１３１Ｉ－ＭＩＢＧ ＳＰＥＣＴ对４５例病人肾上腺髓质图像，结果原发性高血压组７５％患者４８ｈ呈稀疏显像。肾上腺髓质增生组患者腺体均增大，２４ｈ即成较清晰至清晰显像；嗜铬细胞瘤组２４ｈ即成显著显像，ＥＣＴ显像结果与病理／手术一致。表明该技术对嗜铬细胞瘤定位与定性诊断的敏感性，特异性及准确性都高于Ｂ超，ＣＴ与尿ＶＭＡ测定。     

脑外伤患者的SPECT显像与CT对比观察

对４８例脑外伤２进行了＾９９ｍＴｃ－ＥＣＤ ＳＰＥＣＴ脑血流灌注显像。其中４１例在ＳＰＥＣＴ检查的前后两周同时行脑ＣＴ检查，结果ＳＰＥＣＴ对轻、中、重型外伤的检出率分别为６０％、９０％和１００％；而ＣＴ分别为１０％、６０％和１００％，同一病人中ＳＰＥＣＴ比ＣＴ发现的病灶早、数目多，范围大。对脑外伤综合征及后遗症ＳＰＥＣＴ检出率分别为８０％和９０％，ＣＴ分别为２５％和７１．４２％。显然ＳＰＥＣＴ探测     

双能γ射线穿透法测量土壤密度和水含量

本文描述用＾２４１Ａｍ和＾１３７Ｃｓ两个放射源从同一铅屏蔽容器和准直器射出两种能量的γ射线窄束，穿透土壤样品后用ＮａＩ（ＴＩ）多道γ谱仪测量６０和６６２ｋｅＶγ射线的峰感性区计数率，依据土壤的和水对６０ｋｅＶγ射线的质量衰减系数有较大差异而对６６２ｋｅＶγ射线的质量衰减系数基本相同的特点，测定了土壤样品的密度和水含量。用某种土壤制作一系列已知土壤密度和水含量的标准样品，用这种双能量γ射线穿透法分别     

高能离子注入对聚酰亚胺薄膜硬度的影响

报道了聚酰亚胺薄膜在高能（６５０ｋｅＶ－２ＭｅＶ）Ｂ＾＋、Ｃ＾＋和Ｃｕ＾＋离子注入后硬度的变化。对注入样品进行了显微硬度测量和ＸＰＳ及ＲＢＳ分析，观察了硬度与离子种类、能量及注入剂量的依赖关系。结果表明，离子注入之后薄膜样品的显微硬度值明显提高，注入离子在样品中的电子能量损失对聚合物材料改性起着关键作用。ＸＰＳ和ＲＢＳ分析显示，离子注入之后聚酰亚胺薄膜中Ｃ的含量增加，形成了以苯环结构为主的新的交联     

^99mTc—MIBI SPECT与^18F—FDG PET诊断胶质瘤复发及恶变对比分析

对２８例经过治疗的胶质瘤患者进行Ｇｄ－ＤＴＰＡＭＲＩ和＾１８Ｆ－ＦＤＧＰＥＴ显像，其中１４例同时进行＾９９ｍＴｃ－ＭＩＢＩＳＰＥＣＴ显像，并与治疗前解剖影像对比，ＰＥＴ结果发现１４例高代谢，１０例低代谢，４例瘤灶中心坏死，周边ＦＤＧ环状摄取，８例首次手术病理Ｉ－Ⅱ级星形细胞瘤患者中５例为高代谢，＾１８Ｆ－ＦＤＧＰＥＴ和＾９９ｍＴＣ－ＭＩＢＩＳＰＥＣＴ诊断胶质瘤复发及恶变的灵敏度依次为９３．３％，９     

肝脏肿瘤显像剂^99mTc（V）—DMSA的应用

对比了不同标记条件下得到的标记化合物在移植不同肿瘤小鼠体内的分布。选择最佳条件可使瘤／肝比值提高到２．５－３．０左右。动物实验及临床显像均证明＾９９ｍＴｃ（Ｖ）－ＤＭＳＡ不仅适用于原发性肝癌显像，也适用于肝内转移癌的显像。证明了ｐＨ在８．２８－８．４５标记率最高。经应用于５５例肝脏占位性病变病人的ＳＰＥＣＴ显像，肝癌阳性显像阳性率达８９．５％。     

Implementation and preliminary investigation of analytical methodsfor correction of distance-dependent resolution variation and uniformattenuation in 3D brain SPECT

Spatial resolution variation as a function of distance from collimator surface in single photon emission computed tomography (SPECT) is a major obstacle for quantitative imaging. This work investigated two analytical inversion methods for correcting the distance-dependent resolution variation, as well as uniform attenuation in brain SPECT studies. The first one utilizes an accurately measured resolution variation kernel, but derives an approximated inversion formula. The second one derives an accurate inversion formula, but approximates the resolution variation kernel. Reconstructed images using the first method showed a better resolution recovery at the periphery of field-of-view (FOV), consistent with the theory that the inversion formula is approximated for far-field regions. The second method restored resolution better at the central area of FOV, consistent with the approach that the resolution kernel is approximated for near-field regions. The second method is more sensitive to the approximation. The first one is more robust to the approximation and, therefore, can be a better choice for quantitative SPECT imaging     

High-resolution SPECT for small-animal imaging

1Introduction The rapid advance in molecular biology and the increasing use of transgenic mice as models of human biology and diseases have led to significant interests in the development of noninvasive,high-resolution,in vivo imaging techniques for small animals[1-4].Medi-cal imaging techniques including ultrasound(US),computed tomography(CT),magnetic resonance im-aging(MRI),positron emission tomography(PET),and single-photon emission computed tomography(SPECT),are contributing to this …     

高分辨micro-SPECT成像系统针孔准直器的优化设计

为了最大限度地减少γ射线在针孔准直器上的透射和散射效应,采用蒙特卡罗方法对单光子发射计算机断层(SPECT)成像系统使用的针孔准直器进行优化.模拟计算结果与实验测试得到的系统灵敏度和空间分辨率曲线相符,达到了高分辨小动物成像的要求.     

基于LaBr3(Ce)晶体耦合SiPM阵列的可变角分辨率伽玛相机的设计与研制

编码孔径成像技术由于探测效率高、信噪比高、角分辨率好、成像质量稳定可靠等优点而广泛应用于核安全、核设施的去污及退役的测量、核医学等领域。建立通过改变编码准直器和探测器之间距离进而实现可变角分辨的伽玛成像系统。整个成像系统主要由编码准直器、位置灵敏探测(position sensitive detector, PSD)、数据采集卡以及图像重建系统组成。该成像系统的编码准直器采用修正均匀冗余阵列(modified uniformly redundant array, MURA)编码方式,为了保障对较高能量射线的探测能力,编码准直器的材料采用含钨量90%的钨铜合金,PSD通过LaBr₃(Ce)晶体耦合SiPM阵列组成,重建算法采用的是直接互卷积算法,快速高效。测试结果显示,整个位置灵敏探测器的平均能量分辨率为4.96%(662 keV);该辐射成像系统可以准确地对Am-241、Cs-137、Co-60进行清晰成像,并通过改变编码准直器和探测器之间的距离成功分辨出两个Cs-137点源的位置。     

断层屏蔽SPECT的性能和蒙特卡罗模拟

断层屏蔽具有灵敏度高、采集时间短的特点,在临床应用中有很好的前景.通过物理模型和蒙特卡罗模拟计算,探讨了断层屏蔽SPECT的灵敏度、空间分辨率和信噪比,并提出不同半径的数据分组可以有效和直观的进行图像判别,便于图像重建.     

A high-resolution small animal SPECT system developed at Tsinghua

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

断层屏蔽SPECT成像法探讨

本文以空间积分原理为基础,以逐渐逼近法为图像重建的核心,探讨了可实现断层屏蔽的SPECT成像的途径.与传统的SPECT成像方法比较,它具有高的灵敏度和数据获取速度快的特点.由于无须用机械装置将γ照相机旋转,消除了运动带来的误差,提高了成像的质量.本文用线性方程组的松弛解法对无散射和无噪音的二维空间的模拟数据进行了验算,证明逐渐逼近法能逐渐逼近到放射性分布区域,并能基本给出分布形式.     

X射线源针孔成像系统优化设计研究

为提高X射线源针孔成像系统的性能,对成像能区为10~100 keV的X射线源针孔成像系统进行了优化设计研究。综合应用了理论分析和蒙特卡罗模拟的方法,首先根据X射线波长、准直器角响应和X射线穿透效应对针孔成像的不同影响结果设计了可有效控制成像分辨率和成像面积变化的船底型准直器,随后用蒙特卡罗方法对使用该准直器的针孔成像系统进行了模拟验证。结果表明,对于100 keV以下的X射线,经船底型准直器后,成像的空间分辨率和亮斑亮度较稳定,能得到相对准确的X射线源定位、定量信息。     

Optimization of the extraction facilities of an electron accelerator – bremsstrahlung source for the pulsed photonuclear method

The objective of the present work is to select the material and thickness of an electron-beam converter and filter and a bremsstrahlung collimator for designing the extraction facilities of an accelerator in an experimental setup for studying the photonuclear method. Numerical modeling of the conversion of electrons into bremsstrahlung in the electron-beam converter and filter and passage of the bremsstrahlung in the collimator is performed. The following main criteria are optimized: the neutron yield from the fissile material under bremsstrahlung, the radiation loads on the content of the irradiated container, and the radiation background. The data obtained are used to design and build the target block at the exit of the electron accelerator, including the beam converter and filter, and the bremsstrahlung collimator for an experimental model of a fissile-material detection facility based on the U-28 accelerator. Translated from Atomnaya énergiya, Vol. 106, No. 3, pp. 162–167, March, 2009.