图像测量中的亚像素定位方法对比

特征定位主要应用于医疗器械的制造及检测等领域。为了提高定位精度．针对不同的特征应采用不同的定位方法。采用基于矩的方法和曲线插值法在理论及实验上均达到了亚像素精度级，获得了不同算法对特征定位影响。实验结果展示了上述方法的不同效果，并得出在圆心定位与半径测量方面不同方法的精度情况。结论为：曲线插值方法宜用于圆心定位，矩方法宜用于半径测量。     

CT图像中金属伪影的快速校正

CT系统由于检测对象含有金属夹杂而使得重建图像中出现金属伪影,影响图像的质量。针对金属伪影,提出一种快速而稳定的校正方法。首先判断金属投影区域,然后对金属投影进行插值,然后重建图像。最后,在重建的图像中插入金属部分,得到完整的重建图像。数值模拟和实际CT系统的实验表明,该方法能有效的消除金属伪影,并能保留金属信息,恢复图像的完整。该算法计算复杂度很小,计算快速,具有较高的实用价值。     

药物动力学的灰色系统建模方法

本文以给狗一次快速静脉注射常咯啉20mg/kg后所得c-t数据为依据,利用灰色系统(Grey Systems)理论建立不依赖于室分析的药物动力学模型,该模型的计算是用FORTRAN标准语言在IBM计算机上实现的。结果表明,用该模型计算的数据与实测数据之间的平均绝对误差为0.0267;而依据同样数据建立的室模型的平均绝对误差则为0.036。     

Neurobehavioral evaluation for a community with chronic exposure to hydrogen sulfide gas

In May 2000, the Agency for Toxic Substances and Disease Registry of the US government conducted a health investigation in response to community concerns regarding ambient and indoor hydrogen sulfide (H(2)S), odor, and health symptoms in Dakota City, Nebraska. The objective was to determine whether adult residents in an area with repeated exposure to H(2)S showed poorer performance on neurobehavioral tests than unexposed residents. Study participants were required to meet age (#10878;16 years of age) and length of residency (2 years) eligibility requirements. A battery of computer-assisted standardized neurobehavioral tests was administered in English or Spanish. A questionnaire was used to collect information about participants, demographic and health status. Three hundred forty-five people agreed to participate. After the exclusion of 10 persons, analyses were conducted on 335 participants; 171 residents in the target area and 164 residents in the comparison area. The two groups were comparable in demographic characteristics and various health conditions. Overall, neurobehavioral test results for the target and comparison groups were similar. Residence in the H(2)S-exposed area was associated with marginally poorer performance on a test of memory, namely, match to sample score, and a test of grip strength. However, these differences were not significant. Deficits in overall neurobehavioral performance were not associated with exposure to H(2)S in this study.     

GE LightSpeed VCT的最新技术

本文从探测器、球管、分辨率、全息心脏解决方案和剂量优化技术五个方面对GE公司生产的LightSpeed VCT进行介绍,希望读者通过此文能对LightSpeed VCT有一定的了解。     

Physiological alterations of maximal voluntary quadriceps activation by changes of knee joint angle

The purpose of this study was to investigate the influence of different angles of the knee joint on voluntary activation of the quadriceps muscle, estimating the ability of a subject to activate a muscle maximally by means of voluntary contraction. Isometric torque measurement was performed on 6 healthy subjects in 5 degrees intervals between 30 degrees and 90 degrees of knee joint flexion. Superimposed twitches at maximal voluntary contraction (MVC) and at a level of 60% and 40% of the MVC were applied and the voluntary activation estimated. At between 30 degrees and 75 degrees of knee flexion, the maximal extension torque increased at an average rate of 2.67 +/- 0.6 Nm/degree, followed by a decline with further flexion. However, throughout the joint-angle range tested, voluntary activation increased on average by 0.37%/degree with a maximum at 90 degrees of flexion. Due to the influence of joint position it is not possible to generalize results obtained at the knee joint angle of 90 degrees of flexion, which is usually used for the quadriceps twitch-interpolation technique. Consequently, it is useful to investigate voluntary activation deficits in knee joint disorders at a range of knee joint angles that includes, in particular, the more extended joint angles used frequently during daily activity.     

改良盲插法放置鼻肠管技术在危重症患者治疗中的应用

〔摘 要〕 目的：对改良盲插法放置鼻肠管技术在危重症患者治疗中的应用及效果进行研究。方法：选取河南科技大学 第一附属医院 2018 年 1 月至 2020 年 1 月收治的 200 例危重症患者作为研究对象,将其随机分成对照组和观察组,各 100 例。 其中,观察组临床采用改良盲插法放置鼻肠管技术,对照组患者采用常规盲插法放置鼻肠管技术,对两组患者的应用效果 进行比较。结果：观察组患者一次插管成功率为 87.0 %,高于对照组的 59.0 %,且观察组患者插管期间的各种不良反应发 生率明显低于对照组,差异均具有统计学意义（P ＜ 0.05）;两组患者的平均置管时间比较,差异无统计学意义（P ＞ 0.05）。 结论：改良盲插法放置鼻肠管技术在危重症患者治疗中应用具有较好的效果。     

投影插值联合物理校正的自适应CT金属伪影消除算法

目的 为去除CT图像中的金属伪影,提升CT图像质量,本文提出一种结合投影插值和物理校正的自适应加权CT金属伪影消除算法。方法 采用归一化金属投影插值算法得到初始校正投影数据,在此基础上引入金属物理校正模型得到物理校正投影数据,通过自适应权重加权融合两者投影得到最终的校正投影,最后经过滤波反投影重建获得最终校正图像。为验证本文算法的有效性,采用仿真数据和临床数据进行实验。对于仿真数据本文采用PSNR和SSIM定量指标进行评估,而临床数据采用影像专家对结果图像评分方式来比较不同方法的伪影消除性能。结果 在仿真数据实验中,与对比方法结果相比,本文方法结果的PSNR定量指标至少提升了0.2 dB且获得最高SSIM定量指标。影像专家评分结果显示本文方法在临床数据中获得最高的评分结果3.616±0.338（5分制）,与对比方法之间的伪影消除性能差异具有统计学意义（P<0.001）。结论 本文提出的金属伪影消除算法,可有效去除金属伪影,同时保持更多的组织结构信息,减少新伪影的产生。     

The twitch interpolation technique for the estimation of true quadricepsmuscle strength

The aim of this study was to examine the reliability of the twitchinterpolation technique when used to estimate the true isometric knee extensor muscle strength.This included an examination of whether submaximal activation causes any bias in the estimationof the true muscle strength and an examination of the precision of the method. Twenty healthysubjects completed three contraction series, in which the sub-jects were told to perform as if theirvoluntary strength was 60%, 80% or 100% of that determined by a maximalvoluntary contraction (MVC). Electrical muscle stimulations were given at each of five differentcontraction levels in each series. At torque levels above 25% of MVC the relationshipbetween torque and twitch size could be approximated to be linear. The true muscle strength(TMS) could therefore be estimated using linear regression of the twitch–torquerelationship to the torque point of no twitch in each of the three series, termed TMS₆₀, TMS₈₀ and TMS₁₀₀. The TMS₈₀ was slightly lower (P<0·01), median 94% (IQ range 87–101%) of the TMS₁₀₀. The TMS₆₀ was median 99% (IQ range 83–125%)(NS) of TMS₁₀₀, but a few severe outliers were ob-served. In conclusion, we foundthe reliability of the method acceptable for many research purposes, if series with estimated centralactivation of below 40–50% were excluded. The only moderate precision and theslightly lower estimations in subjects applying submaximal does, however, limit its usefulness.     

The accuracy of human population maps for public health application

OBJECTIVES: Human population totals are used for generating burden of disease estimates at global, continental and national scales to help guide priority setting in international health financing. These exercises should be aware of the accuracy of the demographic information used. METHODS: The analysis presented in this paper tests the accuracy of five large-area, public-domain human population distribution data maps against high spatial resolution population census data enumerated in Kenya in 1999. We illustrate the epidemiological significance, by assessing the impact of using these different human population surfaces in determining populations at risk of various levels of climate suitability for malaria transmission. We also describe how areal weighting, pycnophylactic interpolation and accessibility potential interpolation techniques can be used to generate novel human population distribution surfaces from local census information and evaluate to what accuracy this can be achieved. RESULTS: We demonstrate which human population distribution surface performed best and which population interpolation techniques generated the most accurate bespoke distributions. Despite various levels of modelling complexity, the accuracy achieved by the different surfaces was primarily determined by the spatial resolution of the input population data. The simplest technique of areal weighting performed best. CONCLUSIONS: Differences in estimates of populations at risk of malaria in Kenya of over 1 million persons can be generated by the choice of surface, highlighting the importance of these considerations in deriving per capita health metrics in public health. Despite focussing on Kenya the results of these analyses have general application and are discussed in this wider context.