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This work describes a measurement method for assessing dose-related image-quality of CT scans based on the difference detail curve (DDC) method, and showcases its use in a low contrast setting. The method is based on a phantom consisting of elliptical slices of different sizes into which contrast object modules can be inserted. These modules contain contrast objects based on (synthetic) resin mixtures with sucrose (native) or sodium iodine (contrast medium). Mixing ratios are provided to achieve a range of clinically relevant CT-numbers with these materials. The phantom is characterized in terms of contrast accuracy, energy dependency and long-term drift with satisfying results. Contrast accuracy and energy dependency are similar to that of water or soft tissue. Image quality of 655 scans of the phantom acquired at 30 different clinical institutions and with 16 different CT scanner models from 4 manufacturers was assessed by calculating a difference detail curve (DDC) from evaluation of up to 5 human observers using a custom-made software (RadiVates) described in this work. Based on these measurements, inter-observer variability was quantified using a bootstrap method and was shown to be a large contributor to the overall variability. This work demonstrates that assessment of CT image quality is feasible with the aforementioned phantom and DDC method.  相似文献   
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BR55是以血管内皮生长因子受体2为靶点的靶向超声造影剂,可用于检测肿瘤新生血管形成提高诊断准确率。国外已有学者应用BR55进行人体超声分子成像,并显示出良好的安全性和耐受性。本文从BR55组成及特性、动物实验及临床应用等方面对BR55在评估肿瘤新生血管的研究进展进行综述。  相似文献   
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AimTo understand the impact of nurse-related information, through social media usage on undergraduate nursing students’ professional identity.BackgroundPrevious research has addressed professional knowledge and practice that affect the development of undergraduate nursing students’ professional identities. As an increasingly crucial factor in the internet age, social media needs to be explored in-depth for its influence on the professional identity in nursing.DesignSequential explanatory mixed method was used in this study.MethodsIn this quantitative study, participants (N = 698) completed an e-questionnaire survey between June and July of 2020. The relationship between main variables was analyzed by linear regression using SPSS 20.0. Then, face-to-face semi-structured and audio-recorded interviews were carried out among participants (N = 16) between January and March of 2021.ResultsThe quantitative findings indicated that the mean score of professional identity was 93.07 ± 11.96 in participants. The results of the linear regression showed that the year in school, whether nursing was the first choice, online time per day, frequency of reading official accounts related nursing on WeChat and appraisal of the online nurse-related information and so on explained 49.0 % of the variance in professional identity. Four major themes emerged from the qualitative study: 1) increased concern; 2) few and non-professional information; 3) encouraged by positive information; 4) limited impact of negative information.ConclusionsNurse-related information on social media has the potential to have an impact on undergraduate nursing students’ professional identity. Nursing educators should guide undergraduate nursing students to use social media appropriately and assist them in developing their professional identity with it.  相似文献   
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诊断抑郁症的传统方法是通过面对面的评估和交谈。但是,许多患有抑郁症的患者不愿意在早期阶段就医,从而使病情恶化。为了在早期判断抑郁症患者的情况,提出一种利用社交媒体文本信息的时间序列特征和多示例学习的检测模型,考虑到抑郁症状不会立即出现,所以时序样本的使用显得非常重要,因此使用无监督LSTM提取时间序列特征,训练分类器实现二值分类,并使用多示例学习模型来解决不平衡样本问题。首先采用朴素贝叶斯分类器、随机森林、多元社会网络学习和多式抑郁词典学习作为基准,随后利用具有无监督LSTM时间序列功能的多示例学习来更准确地检测抑郁症。在MDDL数据集的基础上,整理出200个调查对象合计7 946条推文信息,并按照训练测试比为8:2的实验得到结果如下:在准确率、精度,召回率和F1得分上分别达到75.0%、76.0%、73.0%、74.5%。结果表明,通过社交媒体中的文本数据,采用机器学习进行早期抑郁症检测是可行的。此外,通过大量的消融实验也证实,采用时间序列特征的方法要比传统的基准模型方法能够获得更好的性能。  相似文献   
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If arteries penetrate bones through foramina, regional artery blood flow rates can be estimated from the foramen sizes. Femoral bone blood flow rates estimated from nutrient foramen sizes were previously not absolute, but only a relative blood flow index (Qi), because the size relationship between the foramen and the occupying artery was unknown. The current study used vascular contrast and micro-computerized tomographic scanning to investigate femoral nutrient foramen and nutrient artery sizes in three groups of sub-adult chickens (non-laying hens, laying hens, and roosters) of similar ages. The results indicate that the cross-sectional area of the nutrient artery lumen occupies approximately 20.2 ± 4.1% of the foramen for femora with only one foramen. Artery lumen size is significantly correlated with foramen size. Vascular contrast imaging is capable of estimating blood flow rates through nutrient arteries, as blood flow rates estimated from artery lumen casts are similar to blood flow rates measured by infusion of fluorescent-labeled microspheres. Laying hens tend to have higher nutrient artery perfusion rates than non-laying hens, probably due to extra oxygen and calcium requirements for eggshell production, although the calculated blood flow difference was not statistically significant. Histological embedding and sectioning along with vascular contrast imaging reveal variable nutrient foramen morphology and nutrient artery location among femora with more than one nutrient foramen.  相似文献   
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目的鼻内镜等离子辅助下鼻前庭囊肿切除与传统齿龈切口切除鼻前庭囊肿临床效果分析。方法回顾性的分析2015年03月-2019年01月在本院就诊90例鼻前庭囊肿患者,其中45例患者行鼻内镜低温等离子辅助下鼻前庭囊肿切除术(等离子组),45例患者行传统齿龈切口切除鼻前庭囊肿(齿龈组),(两种手术均经同一医生在相同条件下行手术治疗),对比两组的手术时间,术中出血,术后疼痛(采用疼痛VAS评分),术后感染复发等情况。结果等离子组较齿龈组手术时间短、出血量少,术后疼痛轻,恢复快。结论鼻内镜下低温等离子辅助治疗鼻前庭囊肿是治疗鼻前庭囊肿的有效术式,且优于传统术式。  相似文献   
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陈丹丹  万业达  何辉  刘妍 《天津医药》2022,50(9):980-983
目的 探讨超声造影判定甲状旁腺切除术加自体甲状旁腺异位移植术后移植物是否成活的价值。方法 收集因肾功能衰竭并发继发性甲状旁腺功能亢进而行甲状旁腺自体异位移植术的患者17例。每例患者于未行动静脉造瘘术的前臂皮下与脂肪之间移植4枚甲状旁腺组织,共68枚。在移植术后15~21 d进行超声造影检查,观察移植物的血供强化情况,估测移植后的甲状旁腺是否成活并具有分泌功能。按照移植物是否全部出现强化表现分为部分移植成功组与全部移植成功组,并以术后30 d双侧头静脉甲状旁腺激素水平对比判定移植物是否成活。结果 17例患者中,全部移植成功组8例,部分移植成功组9例,移植侧头静脉甲状旁腺激素水平高于非移植侧,全部移植成功组头静脉甲状旁腺激素水平高于部分移植成功组,差异有统计学意义(P<0.05)。结论 超声造影可以更准确、更有针对性及更早期地评价甲状旁腺自体异位移植的成活率。  相似文献   
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