In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative...In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative time-reversal electro- magnetic waves, which contain information about the periodic stratified medium, is computed in pulse-echo mode. Using the relationship between the focal peak value and the relative permittivity of the periodic stratified medium, the relative permittivity can be obtained by measuring the focal peak value. Numerical simulations are conducted, and the results demonstrate the feasibility of the proposed approach to the measurement of the relative permittivity of a periodic stratified medium.展开更多
目的利用小剂量监测技术探讨对比剂到达主肺动脉的达峰时间和峰值与个体因素之间的关系。方法 174例患者以4 m L/s注射对比剂15 m L,注射对比剂后延迟0 s,用Test Bolus技术在气管分叉水平下2 cm同层动态扫描主肺动脉,用灌注软件分析主...目的利用小剂量监测技术探讨对比剂到达主肺动脉的达峰时间和峰值与个体因素之间的关系。方法 174例患者以4 m L/s注射对比剂15 m L,注射对比剂后延迟0 s,用Test Bolus技术在气管分叉水平下2 cm同层动态扫描主肺动脉,用灌注软件分析主肺动脉的时间—密度曲线,获得其达峰时间和峰值。采用直线回归分析和多因素逐步回归法分析患者的性别、年龄、身高、体重、心率、收缩压、舒张压、平均动脉压,是否有心脏病、糖尿病或化疗史等因素与对比剂到达主肺动脉的达峰时间和峰值的关系。结果根据患者个体相关因素得出回归方程:达峰时间(s)=6.61+0.04×体重(kg);峰值(Hu)=699.18-1.4×体重(kg)-1.49×身高(cm)-11.22×达峰时间(s)。结论评估患者的个体因素后根据达峰时间和峰值的回归方程可计算出患者行肺动脉CT血管造影时注射对比剂后的延迟时间和峰值。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61071031,61107018,and 61201089)the Research Fund for the Doctoral Program of Higher Education of China(Grant Nos.20100185110021 and 20120185130001)+2 种基金the Program for Changjiang Scholars and Innovation Team in University,China(Grant No.IRT1113)the Natural Science Foundation of the Higher Education Institutions of Anhui Province(Grant No.KJ2013Z287)Fundamental Research Fund for the Central Universities(Grant No.ZYGX2011YB018)
文摘In this paper, we present a new method to determine the relative permittivity of periodic stratified media using the iterative time-reversal method. Based on transmission line theory, the focal peak value of iterative time-reversal electro- magnetic waves, which contain information about the periodic stratified medium, is computed in pulse-echo mode. Using the relationship between the focal peak value and the relative permittivity of the periodic stratified medium, the relative permittivity can be obtained by measuring the focal peak value. Numerical simulations are conducted, and the results demonstrate the feasibility of the proposed approach to the measurement of the relative permittivity of a periodic stratified medium.
文摘目的利用小剂量监测技术探讨对比剂到达主肺动脉的达峰时间和峰值与个体因素之间的关系。方法 174例患者以4 m L/s注射对比剂15 m L,注射对比剂后延迟0 s,用Test Bolus技术在气管分叉水平下2 cm同层动态扫描主肺动脉,用灌注软件分析主肺动脉的时间—密度曲线,获得其达峰时间和峰值。采用直线回归分析和多因素逐步回归法分析患者的性别、年龄、身高、体重、心率、收缩压、舒张压、平均动脉压,是否有心脏病、糖尿病或化疗史等因素与对比剂到达主肺动脉的达峰时间和峰值的关系。结果根据患者个体相关因素得出回归方程:达峰时间(s)=6.61+0.04×体重(kg);峰值(Hu)=699.18-1.4×体重(kg)-1.49×身高(cm)-11.22×达峰时间(s)。结论评估患者的个体因素后根据达峰时间和峰值的回归方程可计算出患者行肺动脉CT血管造影时注射对比剂后的延迟时间和峰值。