基于CPNet的相对图像质量评估

对于两幅不同质量的图像,人眼视觉系统(Human Visual System,HVS)能够比较容易地区分两幅图像间的质量差异,因此通过模拟HVS来判断两幅图像的相对质量比给出图像的绝对质量分数更加准确。文中提出了一种用于评估图像间相对质量的CPNet(Compare-net)模型,该模型是一种分数无关类型的算法,利用图像组合的形式解决数据量的限制,相比绝对质量分数标签,提出的相对质量标签以及相对质量顺序标签具有更广阔的应用场景,并且获取方式更加方便、准确。首先,通过分析卷积神经网络结构相关参数对网络性能的影响,来构建合理的网络基础结构;其次,以双通道输入网络和设计特征求差的方式得到两幅图像的质量差异特征,并结合图像对相对质量标签来完成分类学习;最后,通过在公共数据库上的实验证明了该算法的精度优于其他算法。所提算法在相同参考图像类型实验中分别取得了0.971和0.947的最优精度;在不同参考图像类型实验上也取得了很有竞争力的精度,分别为0.926和0.860。另外,设计了三通道网络并进行实验来探究将所提算法扩展到多通道的可能性。

128-slice Dual-source Computed Tomography Coronary Angiography in Patients with Atrial Fibrillation: Image Quality and Radiation Dose of Prospectively Electrocardiogram-triggered Sequential Scan Compared with Retrospectively Electrocardiogram-gated Spiral

Objective To evaluate the image quality （IQ） and radiation dose of 128-slice dual-source computed tomography （DSCT） coronary angiography using prospectively electrocardiogram （ECG）-triggered sequen- tial scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrilla- tion referred for a second-generation 128-slice DSCT coronary angiography were included in the prospec- tive study. Of them, 17 patients （sequential group） were randomly selected to use a prospectively ECG.~triggered sequential scan, while the other 15 patients （spiral group） used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel- lent （grade 1） to non-assessable （grade 4）, based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each natient were comDared between the two groups. Results The mean heart rate （HR） of the sequential group was 96±27 beats per minute （bpm） with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean FIR （t= 1.91, P=0.243） and HR variation range （t=0.950, P=0.350） had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent （grade 1） in 190/244 （78%） vs. 177/217 （82%） by readerl and 197/245 （80%） vs. 174/214 （81%） by reader2, as non-assessable （grade 4） in 4/244 （2%） vs. 2/217 （1%） by readerl and 6/245 （2%） vs. 4/214 （2%） by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good （1.27＋0.19 vs. 1.25＋0.22, Z=-0.834, P=0.404）. The effective radiation dose of the sequential group reduced significantly compared with the spiral group （4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000）. Conclusion Compared with retrospectively ECG-gated spiral scan, prospectively ECG-triggered sequential DSCT coronary angiography provides similarly diagnostically valuable images in patients with atrial fibrillation and significantly reduces radiation dose.

打开通往新物理世界的大门--“江门中微子实验”先导科技专项及进展

中微子物理是粒子物理最重要的前沿之一,存在众多未解之谜,可能成为超出标准模型的新物理突破口,也是粒子物理、天体物理和宇宙学研究的交叉前沿。大亚湾中微子实验2012年出人意料地发现大的新中微子振荡模式,使近期测量中微子质量顺序和CP相角成为可能。江门中微子实验(原名大亚湾二期实验)2013年得到中科院战略性先导科技专项支持,2015年启动建设,预计2020年投入运行。它以测量中微子质量顺序为核心科学目标,同时精确测量中微子6个振荡参数中的3个,达到好于1%的国际最好水平,使检验中微子混合矩阵的幺正性、发现新物理成为可能。它也可以研究超新星中微子、地球中微子、太阳中微子、大气中微子,寻找暗物质、质子衰变等,在多个领域达到国际先进水平,不仅能对理解微观的粒子物理规律做出重大贡献,也将对宇宙学、天体物理乃至地球物理做出重大贡献。