新型4通道单电源低功耗程控接口脑电放大器的研制

本脑电放大器针对现有同类电路缺点进行改进，采用了最新一代高性能模拟与混合信号集成电路芯片，优化了电路结构并通过精细的电路工艺措施实现了噪声电压1．9μVp-p、共模抑制比100dB、输入阻抗80MΩ、基线漂移小、单电源5V供电和工作电流小于10mA等电路指标，并实现了增益控制和滤波控制的数字化接口。1年的应用表明该放大器安全省电、体积小、结构简单、性能稳定，非常适合作为便携式智能型脑电图仪器的前端。     

麻醉气体吸附器在异氟醚吸入全麻中的应用

目的　评估使用麻气体吸附对异氟醚吸入全麻的病人苏醒和对手术室污染状况的影响。方法　 30例病人 ,ASAⅠ -Ⅱ拟行异氟醚吸入麻醉。麻醉气体的吸附器安装在回路中 ,在苏醒阶段将活瓣打开 ,同时记录苏醒时间、血流动力学和血气分析各项指标。以上病人例在麻醉进行当中 ,废气排气口接废气吸收器 ,同时记录吸附器前后麻醉气体的浓度 ,计算麻醉气体的吸附率。结果　病人在清醒期苏醒时间明显缩短 ,与没有用麻醉吸附器相比 ,麻醉吸附器可以明显降低排入手术室麻醉气体的浓度。使用过程中 ,各项血流动力学指标和血气分析指标均正常。结论　麻醉气体吸附器的使用可以明显提高手术室的空气质量 ,同时在麻醉恢复期。病人的苏醒时间明显缩短而且安全可靠。     

信号提取技术在脑机接口系统中的应用

目的以SSVEP为实例探讨脑机接口系统中输出信号的提取方法。方法分别利用功率谱密度估计、独立分量分析和数字滤波器等技术提取脑电信号中的稳态视觉诱发电位，并对上述各种技术提取该信号的独到之处进行讨论。结果本文利用图示方式直观展示了三种信号处理技术在SSVEP提取中的特点。结论将三种信号处理技术用于脑机接口研制与开发的不同阶段，给特征信号的确认、分析和提取带来很大方便。     

Kalman滤波器在医用超声诊断设备声功率计量中的应用

介绍一种医用超声诊断设备声功率计量数据的处理方法。对同一台医用超声诊断设备的同一个换能器多次测量声功率，将测量的数据建立恰当的数学模型，应用Kalman滤波器算法对其进行处理，去除超声诊断设备及换能器本身的声功率输出波动和超声声功率计的测量不稳定误差，最后得到一个相对稳定、真实的超声声功率。经过Kalman滤波嚣处理的超声功率测量数据大大改善了超声功率的测量结果的离散性，与常用的均值处理方法相比，它的结果更能反映超声功率的真实情况，值得推广应用到其它计量数据的处理中。     

下腔静脉滤器预防肺栓塞的评价研究

目的探讨置入下腔静脉滤器预防因下肢静脉血栓脱落引起肺栓塞的效果和安全性。方法15例经造影证实为下肢静脉血栓患者置入下腕静脉滤器，滤器位于双肾静脉水平以下的腔静脉内。3～36个月摄取腹部平片随访复查，观察滤器的形态、位置。结果全部滤器均经股静脉穿刺置入，其中经右股静脉置入11例，左股静脉置入4例，无严重并发症发生。随访发现15只滤器均展开良好，无移位，无1例发生腔静脉阻塞或肺栓塞。结论置入下腕静脉滤器预防肺栓塞是安全、有效的方法。     

白细胞滤器降低临床输血感染的质量评价

目的探讨白细胞滤器性能的质量评价方法,降低输血反应发生率,确保临床患者安全输血. 方法应用全自动血细胞计数仪和Nageotte计数法测定过滤前后血液中白细胞浓度、血小板浓度及胆固醇和甘油三酯浓度. 结果滤过前后悬浮红细胞中的白细胞浓度分别为(7.18±1.84)×109/L和(2.14±2.82)×106/L;白细胞滤除率99.97%;过滤前后血小板计数分别为(166.86±54.23)×109/L和(38.19±11.82)×109/L,血小板去除率77.11%;过滤前后红细胞分别为(5.22±0.65)×1011/L和(4.67±0.612)×1011/L,红细胞回收率89.46%;滤过后胆固醇及甘油三酯浓度明显降低. 结论该白细胞滤器能够滤除绝大多数白细胞,减少输血患者感染机会;高效白细胞滤器的应用达到了确保临床输血安全,减少医院输血后感染和并发症,是临床输血工作中具有科学性和实用性的技术.     

The effect of notch filtering on the waveform of the newborn auditory brainstem response

Abstract

Objective: To identify whether the use of a notch filter significantly affects the morphology or characteristics of the newborn auditory brainstem response (ABR) waveform and so inform future guidance for clinical practice. Design: Waveforms with and without the application of a notch filter were recorded from babies undergoing routine ABR tests at 4000, 1000 and 500 Hz. Any change in response morphology was judged subjectively. Response latency, amplitude, and measurements of response quality and residual noise were noted. An ABR simulator was also used to assess the effect of notch filtering in conditions of low and high mains interference. Results: The use of a notch filter changed waveform morphology for 500 Hz stimuli only in 15% of tests in newborns. Residual noise was lower when 4000 Hz stimuli were used. Response latency, amplitude, and quality were unaffected regardless of stimulus frequency. Tests with the ABR stimulator suggest that these findings can be extended to conditions of high level mains interference. Conclusions: A notch filter should be avoided when testing at 500 Hz, but at higher frequencies appears to carry no penalty.     

A Compact Band-Pass Filter with High Selectivity and Second Harmonic Suppression

The design of a novel band-pass filter with narrow-band features based on an electromagnetic resonator at 6.4 GHz is presented. A prototype is manufactured and characterized in terms of transmission and reflection coefficient. The selective passband and suppression of the second harmonic make the filter suitable to be used in a C band frequency range for radar systems and satellite/terrestrial applications. To avoid substantial interference for this kind of applications, passive components with narrow band features and small dimensions are required. Between 3.6 GHz and 4.2 GHz the band-pass filter with harmonic suppression should have an attenuation of at least 35 dB, whereas for a passband, less than 10% is sufficient.     

Effect of exposure factors on image quality in screening mammography

IntroductionThe aim of this research was to study the effect of exposure factors on image quality for digital screening mammography units in Kuwait which use Tungsten (W) targets with Rhodium (Rh) and Silver (Ag) as filters.MethodsMammography Accreditation Phantom Model 015 was imaged using a Hologic Selenia Digital mammography unit with W targets and Rh and Ag filters. Four images, each at 26, 28, 30, and 32 kVp, were obtained using each target-filter combination (W/Rh and W/Ag). The images were evaluated by five senior technologists for the number of specks, fibers and masses visible on each image. Statistical analysis was carried out using non-parametric tests at p = 0.05 level.ResultsThere were significant changes in the visibility of fibers and specks between different kVp values with W/Rh (p < 0.001). However, with W/Ag combination, significant differences were observed in the fibers only (p < 0.001). Among the kVp values used, 28 kV emerged as the optimal value. Comparison of images obtained with the two filter materials, led to significant differences in the visibility of fibers and specks (p < 0.008). At 32 kVp, there were significant differences in the visibility of specks only (p < 0.008).ConclusionA W/Rh target-filter combination provides better image quality than that provided by W/Ag. In particular, 30 and 32 kVp X-ray beams produce higher quality images than the lower kV values.     

Conversion factors for determining organ doses received by paediatric patients in high-resolution single slice computed tomography with narrow collimation

Estimations of organ doses D_T received during computed tomographic examinations are usually performed by applying conversion factors to basic dose indicators like the computed tomography dose index (CTDI) or the dose-length-product (DLP). In addition to the existing conversion factors for beam apertures of 5 mm or 10 mm, we present new DLP-D_T conversion factors adapted to high-resolution CT (HRCT) examinations of infants and young children with beam apertures of the order of 1 mm and under consideration of bow tie filtration. Calculations are performed on mathematical MIRD phantoms for an age range from 0, 1, 5, 10, 15 up to (for comparison) 30 years by adapting PCXMC, a Monte Carlo algorithm originally developed by STUK (Helsinki, Finland) for dose reconstructions in projection radiography. For this purpose, each single slice CT examination is approximated by a series of corresponding virtual planar radiographies comprising all focus positions. The transformation of CT exposure parameters into exposure parameters of the series of corresponding planar radiographies is performed by a specially developed algorithm called XCT. The DLP values are evaluated using the EGSRay code. The new method is verified at a beam aperture of 10 mm by comparison with formerly published conversion factors. We show that the higher spatial resolution leads to an enhanced DLP-D_T conversion factor if a small organ (e. g. thyroid gland, mammae, uterus, ovaries, testes) is exactly met by the chosen CT slice, while the conversion factor is drastically reduced if the chosen CT slice is positioned above or below the organ. This effect is utilized for dose-saving examinations with only a few single slices instead a full scan, which technique is applied in about 10% of all paediatric chest CT examinations.