SPECT心肌重建图像的左心室长轴自动定位方法

设计并实现了一种单光子发射断层成像(SPECT)心肌重建图像的左心室长轴自动定位算法。首先通过迭代阈值方法实现原始图像的分割去噪;然后基于连续区块理论,通过先验知识与约束条件自动提取三维感兴趣区(ROI),排除其他器官与噪声的干扰;下一步对数据进行重采样操作,改善数据质量,并应用形态学中的骨架化算法得到足够的、能够描述心肌轮廓的采样点;在确定合适的、能够在XY方向完整描述心肌形状的平面(α平面)后,通过二次曲线拟合得到XY方向偏角(α角);随后通过插值方法沿α角与Z轴方向获取新的截面(β平面),并在β平面内二次曲线拟合得到仰角β角,α角与β角便给出了左心室长轴的定位。最后,本算法在原始模体数据、重建数据以及含噪声重建数据各49组测试中,全部定位成功,且平均绝对误差小于5°,并对真实临床SPECT心肌图像数据实现了成功自动定位。     

微波辐射对家兔血清心肌酶活性及心脏血流动力学的影响

采用平均功率密度为100 mW/cm²和200 mW/cm²的微波照射新西兰家兔20 min,探讨微波辐射对家兔心肌酶活性及心脏血流动力学影响及其意义。结果表明,微波照射5 min后,家兔呼吸(R)、心率(HR)加快。100 mW/cm²照射10～15 min后,家兔血压(BP)和左心室收缩压(LVSP)升高,左心室内压最大上升速率(+dp/dtm)和左心室内压最大下降速率(-dp/dtm)增加,左心室舒张压(LVDP)和左心室终末舒张压(LVEDP)下降,等容舒张时间室内压下降的时间常数(T)值减小;心电图(ECG)R波、QR波异常,偶发全身抽搐。200 mW/cm²照射5 min后,ECG异常以R波、QR波畸形较多,有锯齿形波,出现多次全身抽搐;照射15～20 min时,LVDP明显下降,T值减小,+dp/dtm和-dp/dtm明显增加。照射停止后,各组家兔R、HR立刻减慢,BP下降。停止照射6 h时,R、HR继续减慢,BP不断下降,LVSP逐渐降低,+dp/dtm和-dp/dtm减少,LVDP和LVEDP逐渐升高,T值增大。照射后各组家兔血清心肌酶活性明显升高。实验证明高功率微波辐射对家兔心脏结构和舒缩功能有明显影响,且损伤作用与照射强度密切相关。     

系统性硬皮病心肌损害在冷诱导心肌断层显像和超声心动图的表现

应用＾９９ｍＴｃ－ＭＩＢＩ对２３例系统性硬皮病（ＳＳＣ）病人进行了心肌断层显像冷诱导试验,并同期应用于维超声心动图检测左心室功能和室壁运动。结果表明,１４例病人（６０．９％）有心肌放射性分布异常,其中３例可逆性缺陷６个节段,５例固定性缺损９个节段,６例两种缺损共存１４个节段;心脂显像异常率在雷诺现象（ＲＰ）组和无ＲＰ组之间显著性差异（０．５〉Ｐ〉０．２５）;心肌显像异常组病人的左室射血分数、每搏输     

FT-3103型核心脏功能仪在冠心病中的应用

近年来,国外已先后应用γ照相机和核听诊器来测定左心室喷血分数以反映左心室的泵功能。国内北京阜外医院首先报告应用核听诊器测定左心室喷血分数的临床意义。1980年上海市第六人民医院与上海电子仪器厂协作研制成FT-3103型核心脏功能仪并应用于临床,现将结果报道如下。     

静息门控心肌显像室壁增厚率判断心肌梗死存活心肌的价值

探讨99mTc-甲氧基异丁基异腈(MIBI)门控心肌灌注显像所获得的室壁增厚信息在判断冠心病心肌梗死患者中存活心肌的价值.26例确诊的冠心病心肌梗死的男性患者,均在2周内完成12导联心电图(EKG)、99mTc-MIBI静息门控心肌灌注显像、18F-脱氧葡萄糖(FDG)心肌代谢显像,所有病人均接受冠状动脉造影(CAG).在双核素心肌显像结果提示为缺血存活心肌的心肌节段中,MIBI分布缺损但室壁增厚(WT)正常的心肌节段占双核素显像结果提示为缺血存活心肌节段的68.2%;在双核素心肌显像结果提示为梗死心肌的心肌节段中,MIBI分布缺损且WT异常的心肌节段占双核素显像结果提示为梗死心肌节段的96.8%.静息门控心肌灌注显像所获得的血流灌注和室壁增厚信息与99mTc-MIBI/18F-FDG双核素心肌显像结果具有较高的符合率,故在单纯的心肌血流灌注图像的基础上,结合室壁增厚信息与传统的心肌灌注显像相比有助于检出更多的存活心肌.     

多晶γ照相机与单晶γ照相机计算精度的比较

在用多品闪烁γ照相机做心脏动态的研究中,一个非常重要的有生理意义的参数是左心室射血分数,而限制左心室射血分数计算精度的重要参数之一是统计误差。     

心肌灌注显像剂~(99m)Tc-TBI药盒的初步研究

~(99m)Tc-TBI的动物分布和动力学研究表明,它在心肌有较高的浓集,具有足够长的心肌保留和比较快的血清除,狗的心肌显像及临床试验都取得了良好的结果,说明它是一个有价值的心肌灌注显像剂。     

99mTc标记新型硼酸结构快速心肌灌注显像药物的制备及初步显像评价

^99mTc-TEBO为临床批准的快速心肌灌注显像药物,该药物初始摄取高,但心肌滞留不稳定,为此,本研究通过优化其硼酸结构,分别制备标记物^99mTc-2SP、^99mTc-4LPA及^99mTc-2MDM,制备时间均为30 min,均为无色澄明液体,放化纯度均>95%,分别在健康小型猪体内进行SPECT动态显像,并与99mTc TEBO进行对比。结果表明：^99mTc-TEBO注射后0~5 min,左室心肌快速摄取,但随后心肌放射性迅速洗脱,在10 min时心肌约洗脱至峰值的75%,与心血池放射性浓度比值为1.63。^99mTc-2SP引入2-甲磺酰基吡啶-5-硼酸基后心肌初始摄取高,心肌滞留时间明显延长,心肌洗脱较缓慢,左室心肌均清晰显影,在第10 min时心肌摄取仍可保持峰值的95%,与心血池放射性浓度比值为3.75,明显高于^99mTc-TEBO。而另外两种显像剂^99mTc-4LPA和^99mTc-2MDM在注射后15 min内显像不理想。因此,^99mTc-2SP是有潜力的心肌灌注显像药物。     

某些中药中黄酮化合物强心作用机制的研究

本文实验表明:黄酮的强心作用性质与ISO有所不同,并证实其作用与心肌β受体关系不大,所试十种黄酮对心肌PDE都有抑制作用,但它们对cAMP-PDE抑制作用比cGMP-PDE要强,也证明檞皮素能提高心肌细胞内cAMP水平,而对cGMP含量无影响。因此黄酮强心作用可能是通过抑制心肌细胞内cAMP-PDE活性的结果。     

原发性高血压病患者99Tcm-MIBI心肌显像及其左室心肌质量测定

对33例临床确诊的原发性高血压病患者和18例正常对照者进行常规^99Tc^m—MIBI心肌显像后重建HSA、HVA和LVA，并对图像进行分析和打印，利用体视学原理测定左室心肌质量，以探讨原发性高血压病患者左室心肌质量的改变情况。结果表明，心肌显像结合体视学方法测定左室心肌质量可行且有效，用该方法可测定原发性高血压病患者左室心肌质量，还可同时观察心肌的血供和结构改变情况。     

多能法在炸药和毒品检测中的应用研究

建立了以主坐标分析法为核心的数据处理方法,并用此法对多种材料的数据进行了处理,以此为基础分析了两种炸药和两种毒品,从而证明了多能法在炸药和毒品识别中是一种可行而有效的方法。     

噪声法测量临界装置温度系数实验研究

为了用噪声法测量核电站反应堆的负慢化剂反应性温度系数(MTC),本文在铀溶液临界装置上研究噪声法实验测量反应性温度系数αT,并与周期法测量的αT进行比较。结果表明,两种方法测量的αT趋势基本一致。由于铀溶液临界装置中溶液的反应性温度效应与核电站反应堆的慢化剂温度效应的机理相似,因此本文利用噪声法测量铀溶液临界装置的αT对于核电站反应堆利用噪声法测量MTC有一定的参考价值。     

核辐射脉冲幅度分析的基线卡尔曼滤波估计

本工作从核辐射脉冲信号波形的物理特性分析出发，讨论了卡尔曼滤波方法在实测脉冲信号序列基线估计中的应用效果。实验结果表明了该方法的有效性，这为数字化核辐射多参数测量与分析系统谱分析提供了很好的数据预处理手段。     

Measurement of large negative reactivity of an accelerator-driven system in the Kyoto University Critical Assembly

Large negative reactivity of a subcritical system driven by a pulsed 14 MeV neutron source has been measured in the Kyoto University Critical Assembly. The subcriticality of the accelerator-driven system (ADS) ranged in effective multiplication factor roughly from 0.98 to 0.92, which corresponded to an operational range of an actual ADS proposed by Japan Atomic Energy Agency. As the measurement technique, pulsed neutron method, power spectral analysis for pulsed neutron source, accelerator-beam trip method were employed. From neutron count decay data obtained by the pulsed neutron experiment, not only the prompt-neutron decay constant of fundamental mode but also a higher spatial mode could be derived. The subcriticality was also determined from the fundamental decay constant. The measured cross-power spectral density consisted of a familiar correlated reactor-noise component and many uncorrelated delta-function-like peaks at the integral multiple of pulse repetition frequency. The fundamental prompt-neutron decay constant, i.e., the subcriticality determined from the latter uncorrelated peaks was consistent with that obtained by the above pulsed neutron experiment. However, the magnitude of the former correlated component was reduced with an increase in the subcriticality and eventually this component became almost white at deeply subcritical state ranging in the multiplication factor under 0.95. Consequently, the determination of the decay constant from the correlated component was impossible under such a subcritical state. As data analysis method for the beam trip experiment, both the conventional integral count method and the least-squares inverse kinetics method (LSIKM) were employed. The LSIKM analysis led to the consistent subcriticality with that obtained by the pulsed neutron experiment, while the integral count method significantly underestimated the subcriticality. This underestimation originated from a residual background count, which was maintained after the beam trip. The LSIKM was mostly not influenced by such a slight count rate.     

大米中矿质元素含量测定及分析

采用粉末压片制样,用波长色散X射线荧光光谱法对湖北、四川和黑龙江产地大米中Mn、Fe、Cu、Zn、Mg、P、S、K、Ca 9种元素含量进行测定,并用主成分和聚类分析对结果进行分析。讨论了各目标元素测量条件,运用经验系数法和散射射线作内标对基体效应进行校正,通过测量国家生物标准物质建立了工作曲线。分析结果表明,该方法检出限较低、精密度较好、准确度较高,不同产地大米样品中目标元素含量差异显著。前4个主成分的累计方差贡献率为89.3%,30份大米样品分布在三个区域,分别来自三个产地。聚类分析在阈值为9时,将大米样品分成三类,与主成分分析结果一致。因此矿质元素可作为大米产地溯源的指标。     

Comparison of modal combination methods

A new method of combining modal responses in the response spectrum method of analysis was recently presented by Gupta and Cordero, which is designated here as Gupta's method. It is shown that the response spectrum method in conjunction with Gupta's method of modal combination gives results which are very close to those obtained from the time-history analysis. Further, Gupta's method gives results which are more accurate than other methods of modal combination discussed here, viz., SRSS, Kennedy's and Hadjian's.In Gupta's method response in any mode is split into two parts, the damped periodic part and the rigid part, which are mutually uncorrelated. This is done using a rigid response factor. A simple expression for the rigid response coefficient is presented. The key frequencies in the expression can be evaluated from the motion response spectrum. There is good agreement between the proposed expression and the numerically obtained rigid response coefficient.     

Small-sample modeling method for nonstationary reactor noise analysis

A method of time-series analysis, applicable to nonstationary data, was developed to be used as a tool for surveillance and diagnosis of nuclear power plants. In this method, the nonstationary data are divided into a set of consecutive blocks and a parametric model, called the autoregressive (AR) model, is estimated for each of the blocks. The model parameters are determined by a least-squares algorithm based on the Householder transformation, which ensures a high numerical stability even when the number of samples used for model determination is small. Time-dependent variations of the statistical properties of the measured noise data are characterized by the blockwise evolution of the noise signatures derived from the AR models. As an empirical evaluation, the method was applied to data generated by simulation, and to data obtained from a BWR also. The advantages of the present method over the conventional AR method in numerical stability, spectral resolution and detectability of anomalies have been demonstrated through the analysis of these sample problems.     

基于模糊概率齐次Semi-Markov过程的核动力系统可靠性分析

研究了将模糊集合理论与齐次Semi-Markov过程相结合的方法对清晰事件 模糊概率系统进行可靠性分析。给出三角形模糊数算法和将核动力系统设备可靠性数据源通用数据进行三角形模糊化处理的方法,推导系统状态概率计算的模糊概率齐次Semi-Markov过程算法模型,并给出模糊核矩阵的计算方法。实例研究表明,该方法能够基于已有的通用数据进行系统失效概率的不确定性分析,从而弥补仅采用点估计值所得分析结果的不完备性。     

低水平环境水样中~(90)Sr含量的测定

为了加强对低于国标规定的探测下限(10 mBq/L)的低水平环境水样中90Sr含量的监测,对国标GB6766—1986《水中90Sr放射化学分析方法二-(2-乙基己基)磷酸萃取色层法》中90Sr含量测定条件进行了优化和细化。以P204树脂为分离柱分离90Sr和90Y,观察了水样取样体积,水样、探测效率和电镀源校正测量时在低本底α、β测量仪上测量时间的选择,水样前处理时加入饱和草酸溶液和调溶液pH先后顺序对形成沉淀的影响。测量条件优化后,探测下限可达到0.36 mBq/L,低于国标规定的测量下限10 mBq/L;对低水平环境水样中90Sr含量测量的加标回收率为89.8%～124.0%。以上结果说明,测量条件优化后,方法的准确度良好,可达到对低水平环境水样中90Sr含量(含低水平水样)准确测量的目的。     

Simulation Experiment about the Effects of Core Heterogeneity on the Transient Pressure Behavior in the High-Energy Excursion of Fast Reactor

Gamma-ray dose distribution was measured in an actual ship to study applicability of point kernel method popularly applied to the calculation of γ-ray dose distribution in ships which have usually compartmentalized structures. Measured distribution was used to verify applicability of Monte Carlo method to the analysis of γ-ray dose distribution in the ship. Monte Carlo method was proved to be effective for analysis of r-ray dose distribution in the ship.

Monte Carlo analysis revealed that γ-rays scattered back from steel plates constructing ship hull increase their contribution to measured dose value as the distance between the dose measuring point and γ-rays sources increases. This contribution has not been taken into account in dose distribution calculations for ships by the point kernel method with the usual buildup factor.

Present study also disclosed that feasibility of applying Monte Carlo method to the analysis of γ-rays dose distribution in ships will be enhanced remarkably by utilizing the function adopted in the subroutine RELCOL in the Monte Carlo code MORSE-CG and by applying the source direction biasing technique to save machine time and to improve statistics of the calculated results.