SPECT探头系统的校正与调试

本文阐明了对SPECT探头校正与调试的重要性,特别是对探头校正与调试的具体方法与步骤作了详细介绍。     

Hologic FD原理浅析及维护

本文浅析了FD(平板探测器)的成像原理,探讨空间分辨率的计算方法,并对DR的使用环境,日常维护、维修作了介绍。     

基于平板探测器的DR系统原理及使用维护

针对采用平板探测器技术做为数字化方案实现的直接数字化X线摄影系统，本文重点探讨了平板探测器特点，介绍了系统的工作原理和成像技术，以及系统日常在设备运行过程中的维护技术。     

基才网络环境的远程数字人体中医脉诊智能诊断系统

本文主要阐述了中医学脉诊原理,分析了脉诊数字化的可行性,描述了数字脉诊诊断系统的设计方案及进行家庭远程诊断的设想,并对该系统的应用前景作了展望。     

冰片对大鼠下丘脑单胺类神经递质的影响

目的观察天然冰片对大鼠下丘脑单胺类神经递质 NE、E、5-HT、'DA含量的影响,同时进行其时效和量效关系的观察,初步探讨冰片的作用靶点和作用机理.方法将1 68只Wistar大鼠随机分组,分别灌服生理盐水、1%CMC-NA,以及高、中、低剂量的冰片,每天灌胃2次,在0、45min、24h、72h、120h不同时相,用高效液相-电化学法检测大鼠下丘脑单胺类神经递质NE、E、5-HT、DA含量.结果灌服冰片45min后,冰片中、高剂量组对下丘脑NE含量有显著降低作用(P＜0.05);对下丘脑E的含量,中、高剂量组和CMC-NA组相比有明显的降低作用(P＜0.05);连续灌胃后,不同时相冰片各组下丘脑NE、E含量和CMC-NA组相比,继续呈现不同程度的下降作用,但对下丘脑5-HT无显著影响;在连续灌胃5d后,对 DA含量有显著降低作用(P＜0.05).对大脑皮层乙酰胆碱含量无显著影响,对单胺氧化酶含量有升高的趋势,但除在24h时相,冰片中、高剂量组差异有显著性意义外(P＜0.05),其余时相无显著差异.结论冰片在各个时相均有降低下丘脑NE、E含量的作用,而且随着剂量的递增,对下丘脑中的NE、E含量有逐渐降低的趋势,表现出一定的量效关系.推测芳香开窍中药冰片的药理作用方式可能通过调节中枢神经组织中单胺类神经递质含量达到稳态平衡有关.     

Effects of Air Pollution on Adults with Chronic Obstructive Pulmonary Disease

Few studies have been conducted on the effects of air pollution on patients with chronic obstructive pulmonary disease (COPD). During a 14-mo period, 39 Parisian adults with severe COPD were monitored by their physicians. Daily levels of 4 air pollutants were provided by an urban air-quality network. Exacerbation of COPD was associated only with ozone (O₃) (odds ratio [OR] = 1.44 for a 10-μg/m³ increase in O₃; 95% confidence interval [Cl] = 1.14, 1.82), with a lag of 2-3 days. The effect of O₃ was greater in patients whose carbon dioxide pressure (PaCO₂) was higher than 43 mm Hg (OR = 1.83; 95% Cl = 1.36, 2.47) vs. those with a lower PaCO₂ (OR = 1.26; 95% Cl = 0.90, 1.77). The effect of O₃ was unchanged, regardless of the maintenance medications used. The only air pollutant to which patients with severe COPD were particularly sensitive was O₃.     

An unusual origin of the celiac trunk and the superior mesenteric artery in the thorax

The authors report a case of a 44‐year‐old male found to have unusual origins of the celiac trunk (CT) and superior mesernteric artrery (SMA) as revealed by routine multidetector computed tomograph (MDCT) angiography. The CT and SMA originate from the thoracic aorta (TA) 21 mm and 9 mm above the aortic hiatus, respectively. The median arcuate ligament (MAL) is located at the level of the L1–L2 intervertebral disc. The course of the CT descends in the thoracic cavity making a 14° acute downward angle in front of the TA; below the level of the MAL, the CT descends, making an angle of 47°. The course of the SMA descends at both the thoracic and abdominal level making an angle of 17°, and having an aortomesenteric distance of 9 mm at the level of the third part of the duodenum. In the present case, the supradiaphragmatic origin of the CT and the SMA was determined by their incomplete caudal descent, associated with a pronounced apparent descent of the diaphragm. A thoracic origin of the CT and SMA and the acute downward aortomesenteric angle (17°) associated with a reduced aortomesenteric distance at the level of the third part of the duodenum (9 mm), although no clinical signs are present, may predispose the patient to develop simultaneously a triple syndrome: the compression of CT by MAL (celiac axis compression syndrome), the compression of SMA by MAL (superior mesenteric artery compression syndrome), and the compression of the duodenum by the SMA (superior mesenteric artery syndrome). Clin. Anat. 26:975–979, 2013. © 2013 Wiley Periodicals, Inc.     

Quantification of coronary arterial stenoses in CTA using fuzzy distance transform

Quantification of coronary arterial stenoses is useful for the diagnosis of several coronary heart diseases. Being noninvasive, economical and informative, computed tomographic angiography (CTA) has become a common modality for monitoring disease status and treatment effects. Here, we present a new method for detecting and quantifying coronary arterial stenosis in CTA using fuzzy distance transform (FDT) approach and a new coherence analysis of observed data for computing expected local diameter. FDT allows computing local depth at each image point in the presence of partial voluming and thus, eliminates the need for binarization, commonly, associated with inclusion of additional errors. In the current method, coronary arterial stenoses are detected and their severities are quantified by analyzing FDT values along the medial axis of an arterial tree obtained by its skeletonization. A new skeletal pruning algorithm has been developed toward improving the quality of medial axes and thereby, enhancing the accuracy of stenosis detection and quantification. Further, we have developed a new method to estimate “expected diameter” along a given arterial branch using a new coherence analysis of observed diameter values along the branch. The overall method is completed in the following steps - (1) fuzzy segmentation of coronary artery in CTA, (2) FDT computation of coronary arteries, (3) medial axis computation, (4) estimation of observed and expected diameters along arteries and (5) detection of stenoses and quantification of arterial blockage. The performance of this method has been quantitatively evaluated on a realistic coronary artery phantom dataset with randomly simulated stenoses and the results have been compared with a binary distance transform based and a conventional binary algorithm. The method has also been applied on a clinical CTA dataset from thirteen heart patients and the results have been compared with an expert's quantitative assessment of stenoses. Results of the phantom experiment indicate that the new method (error: 0.53%) is significantly more accurate as compared to both binary distance transform based (error 2.11%) and conventional binary (error 3.71%) methods. Also, the results of the clinical study indicate that the new FDT-based method (kappa coefficient = 87.9%) is highly in agreement with the expert's assessments and, in this respect, outperforms the other two methods (kappa coefficients = 75.2% and 69.5%).     

Shale gas development impacts on surface water quality in Pennsylvania

Concern has been raised in the scientific literature about the environmental implications of extracting natural gas from deep shale formations, and published studies suggest that shale gas development may affect local groundwater quality. The potential for surface water quality degradation has been discussed in prior work, although no empirical analysis of this issue has been published. The potential for large-scale surface water quality degradation has affected regulatory approaches to shale gas development in some US states, despite the dearth of evidence. This paper conducts a large-scale examination of the extent to which shale gas development activities affect surface water quality. Focusing on the Marcellus Shale in Pennsylvania, we estimate the effect of shale gas wells and the release of treated shale gas waste by permitted treatment facilities on observed downstream concentrations of chloride (Cl⁻) and total suspended solids (TSS), controlling for other factors. Results suggest that (i) the treatment of shale gas waste by treatment plants in a watershed raises downstream Cl⁻ concentrations but not TSS concentrations, and (ii) the presence of shale gas wells in a watershed raises downstream TSS concentrations but not Cl⁻ concentrations. These results can inform future voluntary measures taken by shale gas operators and policy approaches taken by regulators to protect surface water quality as the scale of this economically important activity increases.