The Leicester Doppler Phantom—A Digital Electronic Phantom for Ultrasound Pulsed Doppler System Testing

Doppler flow and string phantoms have been used to assess the performance of ultrasound Doppler systems in terms of parameters such as sensitivity, velocity accuracy and sample volume registration. However, because of the nature of their construction, they cannot challenge the accuracy and repeatability of modern digital ultrasound systems or give objective measures of system performance. Electronic Doppler phantoms are able to make use of electronically generated test signals, which may be controlled precisely in terms of frequency, amplitude and timing. The Leicester Electronic Doppler Phantom uses modern digital signal processing methods and field programmable gate array technology to overcome some of the limitations of previously described electronic phantoms. In its present form, it is able to give quantitative graphical assessments of frequency response and range gate characteristics, as well as measures of dynamic range and velocity measurement accuracy. The use of direct acoustic coupling eliminates uncertainties caused by Doppler beam effects, such as intrinsic spectral broadening, but prevents their evaluation. (E-mail: john.gittins@uhl-tr.nhs.uk)     

不同偶联模式的兴奋性氨基酸受体所介导非洲爪蟾卵母细胞跨膜电流的相互影响

目的 研究不同偶联模式的兴奋性氨基酸受体所介导非洲爪蟾卵母细胞跨膜电流的相互影响.方法 用异硫氰酸胍-酚-氯仿法从成年大鼠脑中提取总RNA,以寡聚脱氧胸苷酸纤维素亲和层析法分离出mRNA并注射入非洲爪蟾卵母细胞使表达,通过全细胞双电极电压钳位法,分别以M-胆碱受体Carb,谷氨酸离子型受体激动剂kainate(KA),代谢Ⅰ型受体激动剂quisqualate(QA)及代谢Ⅲ型受体激动剂L-phosphoserine(L-SOP)两两同时灌流有受体表达的非洲爪蟾卵母细胞.结果 3种偶联模式的受体激动后产生的膜电流具有交叉脱敏现象.结论 在多种受体共存的细胞中,受体之间可能存在着广泛的相互作用.     

基层医院放射科CR系统QA、QC浅谈

CR(computed radiography,计算机X线成像)系统的广泛应用,明显提高了放射科X线图像质量,减少了胶片浪费,提高了经济效益和工作效率.     

Automated analysis of images acquired with electronic portal imaging device during delivery of quality assurance plans for inversely optimized arc therapy

This work presents an automated method for comprehensively analyzing EPID images acquired for quality assurance of RapidArc® treatment delivery. In-house-developed software has been used for the analysis and long-term results from measurements on three linacs are presented.     

CT影像质量的保证和控制

本文阐述了主观和客观因素的控制对成像质量的影响，CT扫描的影像质量保证的方法和CT扫描质量控制的内容。     

Improving the ICU: part 2

ICUs are a vital but troubled component of modern health-care systems. Improving ICU performance requires that we shift from a paradigm that concentrates on individual performance, to a systems-oriented approach that emphasizes the need to assess and improve the ICU systems and processes that hinder the ability of individuals to perform their jobs well. This second part of a two-part treatise establishes a practical framework for performance improvement and examines specific strategies to improve ICU performance, including the use of information systems.     

医院内呼吸机整体质量控制/质量保证方案的探讨与实践

提出医院内呼吸机全面质量控制的方案,并结合工作实际对院内在用呼吸机进行了普查和分析。     

兴奋性氨基酸受体所介导细胞钙电流特征及其中L-SOP的作用途径

目的:研究兴奋性氨基酸受体各亚型所介导非洲爪蟾卵母细胞跨膜电流的特征及其中Ⅲ型受体激动剂L-SOP的作用途径.方法:用异硫氰酸胍-酚-氯仿法从成年大鼠脑中提取总RNA,以寡聚脱氧胸苷酸纤维素亲和层析法分离出mRNA并注射入非洲爪蟾卵母细胞使表达,以全细胞双电极电压钳位法灌流此卵母细胞.结果:100 μM KA(kainate)(离子型)产生一主峰电流后缓慢下行,成为一稳定电流平台,最终脱敏,脱敏时间平均为37.57 min.2 μM QA(quisqualate)(代谢Ⅰ型)产生一峰值电流后转为一持续性钙振荡或直接出现钙振荡,振荡维持时间为(6.72±1.33)min,脱敏时间均随激动剂浓度的增加而缩短.0.8 mM L-SOP(L-phosphoserine)(代谢Ⅲ型)灌流产生规律性电流振荡,振荡时间为(20.17±8.47)min.此振荡电流可被代谢Ⅰ型受体拮抗剂L-AP3所拮抗.结论:离子型、代谢Ⅰ型及代谢Ⅲ型受体均产生各自特征电流模型;L-SOP不仅是Ⅲ型受体的激动剂,而且是Ⅰ型受体的弱的激动剂,即细胞振荡电流是L-SOP通过Ⅰ型受体的作用途径而产生.