Maintenance of Millimeter-level Geodetic Reference Framework

The high-precision terrestrial reference frame,as the spatial benchmark for geodesy,is an important national infrastructure.However,due to the influence of nonlinear factors related to geophysical phenomena,the overall maintenance accuracy of the ITRF framework is still at the centimeter level.Therefore,accurately characterizing the true trajectories of linear motion,nonlinear motion,and geocentric motion of the reference station is the key to achieve the construction and maintenance technology of a millimeter level terrestrial reference framework.Based on long-term global and regional GNSS observation data,more Chinese geodesy scientists devoted much efforts to the maintenance of millimeter-level geodetic reference framework.The main contributions of this work included the followings:①Dynamic maintenance of millimeter-level terrestrial reference frame;②Research progress on the method of maintenance of regional reference frame based on GNSS;③The progress of CGCS2000 frame maintenance in millimeter level accuracy;④Reprocessing and reanalysis of two-decade GNSS observation in continental China;⑤Research on current GNSS velocity field model and deformation in Chinese mainland;⑥The preliminary realization and evaluation of CTRF2020.

Radiation Dose Survey of Pediatric Chest Computed Tomography Examinations: A Local Diagnostic Reference Levels Approach to Patient Safety

Objectives: The aim of this work was to initially establish both age and weight driven pediatric diagnostic reference levels (DRLs) for chest computed tomography (CT) examinations performed at tertiary care medical institution. Another aim was to compare the presented data with internationally published ones. This initial data shall serve as basis for establishing a national DRLs values for pediatric diagnostic CT examinations. Methods: Dosimetric indexes were collected for the chest examination for 93 patients during the past 2 years in a tertiary care medical city. Results: The results are within and below the international reported levels for chest CT in several countries. Conclusion: Continuous monitoring of the radiation doses received by the patients in computed tomography is continuous and ongoing process in order to ensure compliance and to optimize clinical imaging protocols. More extensive data acquisition and analysis are required to allow better understanding of the contributing factors leading to less patient radiation dose while preserving the clinical image quality. .

Analysis of Local Diagnostic Reference Levels for Pediatric Patients Undergoing 18F-FDG PET/CT Imaging for Oncology

Background: The PET/CT imaging studies have two doses components the dose from the PET radiopharmaceutical and the other from the low dose CT used for PET images attenuation correction. We have one PET/CT scanner at our institution a Philips Time of Flight scanner. Our local patient’s radiation protection rules requires continuous assessment of radiation doses delivered to our patients. Purposes: The objectives of this study are to develop a weight- based facility DRLs for paediatric F-18-FDG PET-CT imaging for oncology in a large tertiary hospital and to determine whether the calculated DRLs compares with internationally published DRLs. Materials & Methods: Radiation dose data and patient demographics of two-hundreds and sixteen paediatric PET-CT oncology patients imaging procedures from one large tertiary hospital were selected and analysed in order to establish a facility paediatric DRLs. Statistical analysis was performed. Results: The PET dose reference levels ranged between [62 - 525] MBq of injected activity for a range of pediatric age groups. The CTDIvol values were between 3.5 and 16.5 mGy for all age groups. Comparison with current EANM and SNMMI recommendations of patient’s dose are discussed. Conclusion: Our pediatric PET/CT reference levels are higher than the ones reported internationally with notable variations. .

Diagnostic Reference Level in Frontal Chest X-Ray in Western Côte d’Ivoire

Our study aims to determine diagnostic reference levels (DRL) for chest front examination in postero anterior (PA) for optimizing patient entrance surface dose (ESD) and dose-area product (DAP) of patients in west of Côte d’Ivoire. 90 patients from three hospitals undergoing conventional radiology were considered. The ESD and DAP for each patient were obtained during chest radiography (PA) examination. The measurements were performed with the device call Dose-Area Product-meter (DAP-meter) with brand Diamentor M4-KDK, type 11017. The DRL were obtained in applying the 75th percentile statistical method to the obtained ESD and DAP. The obtained DRL in ESD for chest radiography for all rooms is 0.40 mGy and in DAP is 54.85 cGy·cm2. Our DRL for ESD is higher than those obtained in Abidjan District and in other countries like UK and Cameroon. Our DRL for DAP is higher than those from Abidjan and all other countries for which a similar study was made. The comparison of these values to those from Abidjan and other countries, shows us that radiology technicians can make efforts to choose radiological parameters to reduce ESD. They must use convenable the X-rays tube to reduce DAP by reducing the patient exposure surface.

Diagnostic Reference Levels of Adults CT-Scan Imaging in Cameroon: A Pilot Study of Four Commonest CT-Protocols in Five Radiology Departments

CT-scan is the most irradiating tool in diagnostic radiology. For 5% - 10% of diagnostic X-ray procedures, it is responsible for 34% of irradiation according to UNSCEAR. Patients radiation protection must therefore be increased during CT-scan procedures. This requires the rigorous application of optimization principle which imposes to have “diagnostic reference levels”. Objective: The aim of this study was to determine the diagnostic reference levels (DRLs) of the four most frequent CT-scans examinations of adults in Cameroon. Material and Method: It was a cross-sectional pilot study carried out from April to September 2015 in five health facilities using CT-scan in Cameroon. The studied variables were: patients age and sex, type of CT-scan examination (cerebral, chest, abdomino-pelvic, lumbar spine), Used of IV contrast (IV﹣/ IV+), acquisition length, time of tube rotation, voltage (kV), mAs, pitch, thickness of slices, CTDIvol and DLP. For each type of examination, at least 30 patients were included per center, consecutively on the randomly predetermined days. The DRL for each type of examination was defined as the 75th percentile of its PDL and CTDIvol. Results: Of the 696 examinations, 41.2% were cerebral, 26.9% abdomino-pelvic, 17.7% lumbar spine and 14.2% chest. The mean age of patients was 52 ± 15 years [20 - 90 years], 58.9% were 50 years and older. The sex-ratio was 1.26 (55.9% males). The CT machines were 4, 8 and 16 multidetectors. The 75th percentile of DLP or DRLs [standard deviation] was: [1150 ± 278 mGy·cm], [770 ± 477 mGy·cm], [720 ± 170 mGy·cm] and [715 ± 187 mGy·cm] respectively for cerebral, lumbar spine, abdominopelvic and chest CT-scans. Taking in consideration the number of detectors, the 75th percentile of the Dose-Length product decreased with the increase number of detectors for cerebral examinations but was the highest with 16 MDCT for the abdominopelvic, lumbar spine and chest CT-scans. For the chest and lumbar spine examinations, there was a significant increase in patient-dose with the increase in the number of detectors. Conclusion: Our DRLs values lie between the norms of some European countries and those of some African countries. There is remarquable variation in dose for the commonest CT-scans examinations in Cameroon, requiring then an optimization process from these determined DRLs and establishment of national DRLs. Special attention to optimization should be paid when using 16 MDCT.

Establishment of Dose Reference Levels for Nuclear Medicine in Sudan

In this study, a national survey for establishment of Nuclear Medicine (NM) Dose Reference Levels (DRLs) for adult patients was carried out. The Administrated Activity (AAs) (MBq) was collected from six nuclear medicine departments. Factors influencing the image quality were also observed. The established Sudan National DRLs represent the AA value corresponding to 75th percentile of the AA frequency distribution. Generally, Sudan National DRLs and average AAs are comparable with the papers published in the international literature. All Sudanese DRLs values were found within the international range. While it is noted that the Sudanese DRLs is higher than the values of ARSA except for the MIBI pharmaceuticals that used in both parathyroid and myocardial perfusion scan and for 99mTcDTPA that used for Dynamic Renal scan study the DRLs values were decreased. In compared with UNSCEAR 2008 data, the average dose (MBq) for Sudanese we note that the bone scan falls within the average values while it’s lower in all other scans except for parathyroid scan in which the AAAs increase more than twice. When compared to BSS 1996, it showed variation in increased and decreased AAAs. There may be potential for reducing the higher values of AAs, in co-operation with Nuclear Medicine staff.

STUDY ON A PRECISE ON-SPOT CALIBRATION METHOD FOR DISTRIBUTED STEREO REFERENCE POSITION-SETTING

A high precision method used for on-spot calibration of distributed stereoreference position setting is presented. The high measuring accuracy in stereo reference calibrationis derived from using a high precision water level instrument and an accurate height verniercaliper. It settles the problem of reference calibration effectively and accurately, without usinglarge coordinate measuring machines (CMM). It is more adaptable and precise than traditionalcalibration methods applying theodolites or autocollimators. The error sources of this method areanalyzed in detail and several methods are developed to eliminate the calibration error.Anoptimizing swallowtail-like anchor target is developed. Experiments show that the calibrationaccuracy can be limited within 0.06 mm in the range of 3～5 m and 0.03 mm with optimizing anchortarget. This method can be widely used in on-spot calibration.

基于动态基准的低复杂度特种车辆行驶调平控制方法

针对特种车辆行驶调平问题,提出基于动态基准的低复杂度控制方法。整车被分解为由作动器驱动的带有相互耦合特性的悬架节点。建立悬架节点动力学模型,将基于整车行驶动力学模型的位姿混合控制问题,转换为基于全驱型悬架节点动力学模型的单纯位移控制问题。提出并构建动态基准和基准误差,解决现有方法对车身铅垂高依赖和限制的技术瓶颈,同时提高车辆的通过性能。建立基于基准误差的扩张状态观测器,实现动态解耦,并提出一种低复杂度行驶调平控制方法。借助汽车系统仿真软件Carsim验证该方法的有效性。结果表明:与经典基于常值基准的整车型控制方法对比,在所提出方法作用下,车辆的行驶调平精度提高了一个数量级;特别是在路面激励幅度超过作动器行程的工况下,车辆的舒适性和安全性尤为改善。

Radiation Dose from CT-Scan of Childhood’s Head: Results of the First Ivorian Survey in a Single Study Site

Objectives: This study aims to evaluate the level of X-ray doses used in childhood’s head as Local Diagnostic Reference Levels (LDRLs) in computed tomography (CT) at a university hospital in Côte d’Ivoire. The Diagnostic Reference Level (DRL) have been set up and used to prevent unusually high radiation doses used in radiology departments and is therefore an optimization tool for practices and procedures in medical X-ray imaging for the radiation protection of patients. Methods: A prospective study of volume CT dose index (CTDIvol) and dose length product (DLP) was performed on images of childhood’s head obtained from a CT-scanner of 64 bars equipped with the tube current modulation capability and manufactured by Hitachi Medical System. 122 CT-scan data from 55 childhood’s head were analyzed. The scan data were stratified in four age groups: Results: The 75th percentile of CTDIvol and DLP (set as LDRL) obtained with respect to the stratified age groups are: 22.5 mGy and 452.5 mGy∙cm, 27.7 mGy and 690.6 mGy∙cm, 28 mGy and 722.4 mGy∙cm, 33.6 mGy and 736.8 mGy∙cm respectively. These outcome values increase with respect to the age of pediatric patients and are comparable to DRLs values obtained internationally. Conclusions: Obtaining good image quality while using low dose in children’s head computed tomography for radiation protection require to setup more surveys in Côte d’Ivoire for regional and national DRL. We proposed through this survey LDRLs in terms of CTDIvol and DLP, comparable to international DRLs values. This survey will be strengthened by additional surveys in order to obtain national DRLs for the radiation protection of the child patient in Côte d’Ivoire.

任务多标准优先级排序方法综述

任务的多标准优先级排序(multi-criteria priority ranking)涉及在可能存在冲突的多个标准下为大量任务计算优先级,以便决策者能够高效地分配资源,优先处理更为关键的任务,进而提高整体工作效率。经过近二十年的持续修改与扩展,目前优先级排序领域已展现众多成熟的经典方法;且随着大数据时代的到来,采用新兴技术的排序方法也开始涌现。为了帮助决策者根据不同情境下的优先级排序需求来评估和选择最适合特定应用场景的多标准优先级排序方法,文章阐释了不同多标准优先级排序方法在标准间的可替代性、优缺点、数据输入/输出要求、适用场景等方面的差异,将当前多标准任务优先级排序方法分为:全聚合法、劣势排序法、参考水平法以及基于数据处理技术的优先级排序方法4大类,详细讨论了各类别下代表性方法的基本原理、最新研究结果和优缺点;并总结了当前优先级排序方法研究的热点,包括层次分析法、模糊理论及人工智能辅助排序技术,提出其未来研究方向,涵盖了AI辅助的大数据排序优化、增强排序稳定性以及智能偏好识别。

儿童头颅CT检查不同辐射剂量衡量指标差异性比较及相关性分析

目的:比较容积CT剂量指数(volume CT dose index,CTDI_(VOL))及基于水当量直径的体型特异性剂量估计值(size-specific dose estimate based on water equivalent diameter,SSDE_(WED))在衡量儿童头颅CT辐射剂量中的差异性,并分析CTDI_(VOL)、SSDE_(WED)与曝光量、水当量直径(water equivalent diameter,WED)的相关性,以为临床检查中儿童头颅CT辐射剂量衡量提供参考。方法:回顾性分析2021年1—12月于某院进行头颅CT检查的1297例患儿的临床资料,根据年龄将患儿分为≤1个月组、>1个月~4岁组、>4~10岁组、>10~15岁组。记录患儿的曝光量、年龄、CTDI_(VOL)、剂量长度乘积,并计算WED、转换因子及SSDE_(WED)。比较CTDI_(VOL)与SSDE_(WED)的差异;建立CTDI_(VOL)、SSDE_(WED)与曝光量、WED的回归模型,并采用Pearson分析CTDI_(VOL)、SSDE_(WED)与曝光量、WED之间的相关性;对比国内诊断参考水平(diagnostic reference level,DRL)、欧盟DRL及本医疗机构诊断参考水平(local diagnostic reference level,LDRL)的差异。采用SPSS 25.0统计学软件进行分析。结果:患儿头颅CT的CTDI_(VOL)为(9.22±1.63)mGy,SSDE_(WED)为(8.14±0.84)mGy,CTDI_(VOL)较SSDE_(WED)高13.27%,差异有统计学意义(t=47.66,P<0.001)。CTDI_(VOL)、SSDE_(WED)与曝光量、WED均呈正相关关系(P<0.001);CTDI_(VOL)、SSDE_(WED)与曝光量、WED回归模型拟合性较强(R^(2)为0.58~0.99)。与国内DRL及欧盟DRL比较,LDRL均处于较低水平。结论:在儿童头颅CT辐射剂量衡量中,相较于CTDI_(VOL),SSDE_(WED)对辐射剂量的衡量更准确。同时定期对医疗机构的DRL值进行统计更新并优化检查参数,是减少辐射剂量的重要方式。

中高污染风险水平大米无机成分分析标准物质研制

研制了中高污染风险水平大米无机成分分析系列标准物质。按照JJF 1342—2022《标准物质研制(生产)机构通用要求》、JJF 1343—2022《标准物质的定值及均匀性、稳定性评估》等进行样品采集、加工制备、均匀性检验、稳定性检验,由11家不同行业的权威实验室进行联合定值,并对不确定度进行合成与评定。结果表明,样品粒度分布满足样品加工和检测的要求,具有良好的均匀性和稳定性。该系列大米无机成分分析标准物质共定值Pb、Cd、Cr、As、Cu、Zn、Ni、Mo、Fe、Mn、K、Ca、Mg、Na、Hg、Se 16种元素,定值数据为正态分布或近似正态分布,全部参数F实测值均小于F临界值[F0.05(24,50)=1.74],不同元素均匀性检验引入不确定度为0.20%~2.58%、稳定性检验引入不确定度为0.58%~4.79%、定值测试引入不确定度为0.67%~2.76%、扩展不确定度为6.45%~17.1%,量值准确可靠,不确定度范围评估合理,获批国家二级标准物质证书。研制的3种大米无机成分分析标准物质定值的元素含量梯度范围合理,解决了部分一级标准物质中Pb、Cr、Na、Hg、Se等缺少定值、难以进行计量溯源的问题,扩展了国内中高污染风险水平大米无机成分分析标准物质的范围。

新疆某三甲医院妊娠期甲状腺激素水平参考范围的验证及差异性分析

目的建立本单位检测系统妊娠期甲状腺激素水平参考范围,比较不同年龄阶段孕早、中、晚期女性甲状腺激素水平,为妊娠期健康监护提供理论依据。方法回顾性分析2019年6月-2021年6月本院正常妊娠期女性的甲状腺激素水平,比较不同孕期、不同年龄阶段女性甲状腺激素水平。结果孕早、中、晚期的FT3参考范围为4.45(3.38-5.67)pmol/L、4.08(3.26-5.308)pmol/L、3.94(3.242-5.012)pmol/L;孕早、中、晚期的FT4参考范围为15.46(12.494-20.815)pmol/L、13.66(12.071-18.842)pmol/L、13.27(12.062-16.541)pmol/L;孕早、中、晚期的TSH参考范围为2.14(0.485-3.971)mIU/L、2.11(0.523-3.941)mIU/L和2.12(0.611-3.961)mIU/L;全阶段孕期TPOAb参考范围为2.46(5.562-30.182)IU/Ml。结论不同孕期女性的FT3、FT4、TSH水平具有显著性差异(P<0.05),TPO水平无显著性差异(P>0.05),不同孕期女性的FT4水平分别在四组年龄分组中(≤25岁、>25岁-30岁、>30岁-35岁、>35岁)均具有显著性差异(P<0.05)。

新昌县现代测绘基准服务能力测试与评估

为客观评估新昌县现代测绘基准服务支撑保障能力,对新昌县及周边卫星导航定位基准站、全球卫星导航系统(GNSS)D级网、三等水准网,以及县域的高精度似大地水准面模型相关的基础数据进行统计、分析与处理,结果表明新昌县卫星导航定位基准站网覆盖全面、站网观测质量良好、实时差分定位(RTK)服务水平精度优于±1.0 cm,大地高精度优于±2.5 cm,似大地水准面模型精度优于2.0 cm,能够支撑新昌县经济社会发展,长远来看仍需做好新昌县测绘基准的维持与更新工作。

高压交流断路器标准的主要差异分析

本文主要对GB/T 1984—2014与IEC 62271-100:2021的差异进行分析,主要针对文本差异和基本技术参量差异两个方面,其中文本差异主要分析了适用范围和规范性引用文件、使用条件以及术语和定义;基本技术参量差异主要分析了额定绝缘水平、温升限值、TRV参数以及试验参量的容差。通过以上几个方面的分析,加深对标准理解和规范检测认证。

Effective Dose Levels from Computed Tomography of the Head during Contrast Studies in Nigeria

Background: Diagnostic reference levels for a number of common diagnostic radiological examinations against which individual centres could compare their performance have been recommended by relevant international agencies. Due to variations in different populations globally, local and national diagnostic reference levels are more reliable. To the best of our knowledge, no centre-specific study has been carried out and national surveys are not available. Objective: To establish a preliminary local and national diagnostic reference level in Nigeria. Methods: A pro-spective and cross-sectional study involving 30 conscious paediatrics and adult patients referred for head computed tomography scan. They were positioned supine and scanned according to the standard protocol for head computed tomography with manual mA selection. The total dose-length products were recorded at the end of the pre-contrast and post-contrast sequences respectively. The pre-contrast dose was taken into cognizance in the determination of the post-contrast value. The effective dose was established by multiplying the dose-length product by 0.0023 mSv.mGy-1.cm-1, a conversion coefficient for brain tissue adopted from the European Commission. Statistical Package for Social Sciences version 17.0 was used to analyze the data. Results: 30 paediatrics and adult patients of mixed gender participated in the study. Their ages ranged from 1 to 74 years with a mean age of 41.47 ± 23.30 years. The pre-contrast effective dose ranged from 1.93 mSv to 3.32 mSv with mean of 2.56 ± 0.51 mSv and 75th percentile of 3.11 mSv while the post-contrast effective dose ranged from 4.06 mSv to 6.97 mSv with mean of 5.27 ± 0.97 mSv and 75th percentile of 6.13 mSv. The mean effective dose from this work and two other isolated studies was 3.0 mSv. Conclusion: Although our quantified doses are below threshold limits for occupational exposures they are higher than the recommended level for the public. A further optimization of scanning protocols by the radiographers could lower the effective dose for patients undergoing contrast head computed tomography in our centre and in the country.

国内外物流低碳发展经验借鉴与启示

我国物流行业长期以来呈粗放式发展,能源消耗量、碳排放量一直居高不下。本文以我国“双碳”战略目标的提出为背景,从货运结构、新能源及高新技术应用、包装回收系统、标准化水平等方面剖析了导致我国物流行业碳排放量偏高的关键因素。针对我国物流行业低碳发展存在的突出问题,通过系统梳理和对比分析国内外政府机构及典型物流企业的减碳政策与实践措施,提出物流行业减碳措施。优化物流网络货运结构,形成以铁路和水路为主多式联运并行的发展格局,构建低碳高效的物流运输网络;推动低碳物流设施建设与新技术的应用,强化政府、企业与科研单位合作交流,提升行业整体的低碳化水平;建立政府监管下的碳交易机制,强化物流减碳政策引导,激励物流企业低碳发展,促进全面减排。

农业激光平地机的研究与发展

农业激光平地机的广泛应用,可以显著改善我国农田微地形条件,显著提高农田表面的灌溉效率和水分分布均匀度,同时获得显著的节水、增产、节约劳动力和提高土地利用率等多重效益。综述了国内外农业激光平地机的发展情况,分析了我国农业激光平地机的整体研究现状及关键部件的研究进展,并对近年来国内农业激光平地机及其关键部件的主要研究工作及应用成果进行了论述,探讨了我国农业激光平地机的未来发展趋势和研究方向,以期为后续相关产品的研究提供参考。

基于胸围的固定管电流检查在儿童胸部增强CT中的应用价值

目的:探讨基于胸围的固定管电流检查在幼儿胸部增强CT中的应用价值。方法:回顾性分析171例胸部增强参考病例的病例资料,建立DW与胸围(CC)的回归方程。依据胸围分为CC≤45 cm、45 cm<CC≤55 cm、55 cm<CC≤65 cm及65 cm<CC≤75 cm四个亚组,统计参考病例各亚组容积CT剂量指数(CTDIvol)上四分位数。前瞻性搜集行胸部增强CT检查的患儿96例,按照随机数字表法将患儿分为对照组和实验组。对照组患儿44例,依照CTDIvol设定管电流;实验组患儿52例,依照体型特异性剂量评估值(SSDE)设定管电流。两组参考辐射剂量均为参考病例CTDIvol上四分位数,对比分析两组患儿的图像质量及辐射剂量。结果:参考病例DW与胸围呈较强正相关(R 2=0.911,P<0.001),其回归方程为DW=2.45+0.25×CC。CTDIvol上四分位数分别为2.22 mGy、2.80 mGy、3.80 mGy、6.33 mGy。对照组及实验组患儿的CTDIvol分别为(4.52±0.94)mGy、(2.91±0.50)mGy,差异有统计学意义(Z=-7.65,P<0.001);对照组及实验组患儿的SSDE DW分别为(6.12±0.88)mGy、(3.87±0.52)mGy,差异有统计学意义(Z=-8.13,P<0.001)。实验组的CTDIvol、SSDE DW较对照组分别降低35.62%(1.61/4.52)、36.76%(2.25/6.12)。图像质量客观评价两组间差异有统计学意义(t=4.12、-3.85、4.71,P<0.001);主观评价及信心评分两组间差异无统计学意义(Z=-1.23、t=0.02,P>0.05)。结论:根据患儿胸围计算SSDE DW并以此设置固定管电流检查在临床实践中具有可行性,在满足图像诊断要求的前提下可降低患儿的辐射剂量。