目的:研究64排螺旋X射线计算机体层扫描(CT)机低管电压联合高管电流技术用于肾癌术前诊断的价值。方法:选取医院收治的156例肾癌患者,采用随机数表法将其分为观察组和对照组,每组78例,两组均行全腹部多期增强CT扫描,观察组扫描参数中管...目的:研究64排螺旋X射线计算机体层扫描(CT)机低管电压联合高管电流技术用于肾癌术前诊断的价值。方法:选取医院收治的156例肾癌患者,采用随机数表法将其分为观察组和对照组,每组78例,两组均行全腹部多期增强CT扫描,观察组扫描参数中管电压为90 k V,管电流为550 m A;对照组管电压为120 k V,自动选择管电流。两组对比剂均为碘普罗胺,注射速度均为3.0 ml/s,对比剂剂量分别为1.0 ml/kg、1.5 ml/kg。采集两组皮髓质期(CMP)图像和实质期(NP)图像,记录并计算CMP图像的肿瘤感兴趣区域(ROI)、肾实质ROI、对比度噪声比(CNR)和信噪比(SNR)以及NP图像的肿瘤ROI、肾实质ROI、肾静脉ROI和SNR。采用4分法对两组采集的CMP、NP图像进行评分;对比两组CMP、NP的剂量长度乘积(DLP)和有效剂量(ED)的辐射剂量和总辐射剂量。结果:两组CMP和NP图像质量及主观评分差异均无统计学意义(P>0.05)。观察组CMP、NP的DLP和ED的辐射剂量以及总辐射剂量均低于对照组,其差异有统计学意义(t_(CMP)=5.086,t=9.833;t_(NP)=6.483,t=10.802;t_(总辐射剂量)=10.984;P<0.05)。结论:64排螺旋CT机低管电压联合高管电流技术进行肾癌诊断可清晰显示肾癌患者病灶,同时可降低对比剂使用剂量和辐射剂量,有利于减轻辐射对肾功能的损害。展开更多
在总结相关专利的基础上,本文发明了一种便携式高频X射线机的锂离子电池的供电方法和控制电路。阐述了锂离子电池给X射线管的高压供电和灯丝加热。设计了半桥逆变的主电路方案,以及X射线机的管电压和管电流的反馈检测电路装置。样机总质...在总结相关专利的基础上,本文发明了一种便携式高频X射线机的锂离子电池的供电方法和控制电路。阐述了锂离子电池给X射线管的高压供电和灯丝加热。设计了半桥逆变的主电路方案,以及X射线机的管电压和管电流的反馈检测电路装置。样机总质量1.5 kg,总体积不大于15 cm×15 cm×15 cm。电池组容量可曝光300次,输出电压范围在19~25 V之间,管电压60 k V,波动5%,管电流2 m A,波动8%。样机轻便,体积小,便于携带,且能拍摄出清晰图片,能满足拍片要求。基于半桥逆变的供电方案,其管电流、管电压的波动比全桥逆变供电时要大,即精度会有所降低,但其结构简单,成本降低,体积减少,适合制作小容量的便携式X射线机。展开更多
Traveling Wave Tubes(TWTs) are widely used in the radar and communications system as RF power amplifiers. A highly sophisticated power supply is required by TWT. In order to meet the severe requirements of Traveling W...Traveling Wave Tubes(TWTs) are widely used in the radar and communications system as RF power amplifiers. A highly sophisticated power supply is required by TWT. In order to meet the severe requirements of Traveling Wave Tube Amplifier(TWTA), a novel two-stage topology high voltage converter for TWTA is proposed.The converter is based on Zero-Voltage Switching and Zero-Current Switching(ZVS/ZCS) resonant techniques. The high voltage converter operation principles are investigated and major features of the converter are discussed. The power switching mode of ZVS/ZCS is obtained. The experimental results show that the converter has good soft switching characteristics. Compared to the conventional hard switched Pulse Width Modulation(PWM) techniques, the high efficiency and low ripple of the converter for TWTA are realized. The efficiency of High Voltage Electronic Power Conditioners(HV-EPC) over 93.5% under the condition of 38~46 V input voltage and 260~300 W input power. The switching frequency of first-stage(preregulator) of HV-EPC is 89 k Hz and the switching frequency of second-stage(postregulator) is 44.5 k Hz. The highest output voltage of the HV-EPC is helix voltage which is about –6.8 kV. It is especially suitable for TWTA utilized in space satellite applications due to its high switching frequency and high power density.展开更多
文摘目的:研究64排螺旋X射线计算机体层扫描(CT)机低管电压联合高管电流技术用于肾癌术前诊断的价值。方法:选取医院收治的156例肾癌患者,采用随机数表法将其分为观察组和对照组,每组78例,两组均行全腹部多期增强CT扫描,观察组扫描参数中管电压为90 k V,管电流为550 m A;对照组管电压为120 k V,自动选择管电流。两组对比剂均为碘普罗胺,注射速度均为3.0 ml/s,对比剂剂量分别为1.0 ml/kg、1.5 ml/kg。采集两组皮髓质期(CMP)图像和实质期(NP)图像,记录并计算CMP图像的肿瘤感兴趣区域(ROI)、肾实质ROI、对比度噪声比(CNR)和信噪比(SNR)以及NP图像的肿瘤ROI、肾实质ROI、肾静脉ROI和SNR。采用4分法对两组采集的CMP、NP图像进行评分;对比两组CMP、NP的剂量长度乘积(DLP)和有效剂量(ED)的辐射剂量和总辐射剂量。结果:两组CMP和NP图像质量及主观评分差异均无统计学意义(P>0.05)。观察组CMP、NP的DLP和ED的辐射剂量以及总辐射剂量均低于对照组,其差异有统计学意义(t_(CMP)=5.086,t=9.833;t_(NP)=6.483,t=10.802;t_(总辐射剂量)=10.984;P<0.05)。结论:64排螺旋CT机低管电压联合高管电流技术进行肾癌诊断可清晰显示肾癌患者病灶,同时可降低对比剂使用剂量和辐射剂量,有利于减轻辐射对肾功能的损害。
文摘在总结相关专利的基础上,本文发明了一种便携式高频X射线机的锂离子电池的供电方法和控制电路。阐述了锂离子电池给X射线管的高压供电和灯丝加热。设计了半桥逆变的主电路方案,以及X射线机的管电压和管电流的反馈检测电路装置。样机总质量1.5 kg,总体积不大于15 cm×15 cm×15 cm。电池组容量可曝光300次,输出电压范围在19~25 V之间,管电压60 k V,波动5%,管电流2 m A,波动8%。样机轻便,体积小,便于携带,且能拍摄出清晰图片,能满足拍片要求。基于半桥逆变的供电方案,其管电流、管电压的波动比全桥逆变供电时要大,即精度会有所降低,但其结构简单,成本降低,体积减少,适合制作小容量的便携式X射线机。
文摘Traveling Wave Tubes(TWTs) are widely used in the radar and communications system as RF power amplifiers. A highly sophisticated power supply is required by TWT. In order to meet the severe requirements of Traveling Wave Tube Amplifier(TWTA), a novel two-stage topology high voltage converter for TWTA is proposed.The converter is based on Zero-Voltage Switching and Zero-Current Switching(ZVS/ZCS) resonant techniques. The high voltage converter operation principles are investigated and major features of the converter are discussed. The power switching mode of ZVS/ZCS is obtained. The experimental results show that the converter has good soft switching characteristics. Compared to the conventional hard switched Pulse Width Modulation(PWM) techniques, the high efficiency and low ripple of the converter for TWTA are realized. The efficiency of High Voltage Electronic Power Conditioners(HV-EPC) over 93.5% under the condition of 38~46 V input voltage and 260~300 W input power. The switching frequency of first-stage(preregulator) of HV-EPC is 89 k Hz and the switching frequency of second-stage(postregulator) is 44.5 k Hz. The highest output voltage of the HV-EPC is helix voltage which is about –6.8 kV. It is especially suitable for TWTA utilized in space satellite applications due to its high switching frequency and high power density.
