螺距

多层CT螺距与辐射剂量的关系探讨

Relationship of radiation dose and spiral pitch for multi-slice CT system

不同螺距对螺旋CT图像噪声影响的实验研究

Study of different pitch action on image noise in spiral CT

16层螺旋CT螺距对图像质量的影响

Effects of 16-slice Spiral CT Pitch on Image Quality

结果表明，螺旋CT图像噪声与螺距大小有关。

The result shows that spiral CT image noise is related to the pitch .

本文通过改变螺距大小对螺旋CT图像的噪声进行了分析研究。

Image noise was studied with various pitches .

结果多层面CT机的质量与插值方法、螺距等因素有关。

Results Linear interpolation method and pitch affect the image quality of multi slice CT .

目的探讨多层螺旋CT的扫描参数螺距的变化对辐射剂量的影响。

Objective To study the relations of radiation dose and spiral pitch for multi-slice CT system .

螺旋CT运用螺距的策略

Application Tactics of Spiral CT Pitch

浓度越高，螺距P越大，意味着胆甾相的扭转力随浓度增加而减弱。

The higher the concentration was , the larger the pitch was , implying the twisting power decreased with the increase of concentration .

利用VISUALBASIC的串口通讯来实现滚珠丝杠螺距误差的实时测量、补偿和控制，是一种新的思路和方法。

This is a new method on the real-time measurement , compensation and control of Ball Scroll by using of Visual Basic serial communication .

运用此误差补偿方法对一台配备华中HNC-21系统数控机床螺距补偿后，获得了理想的加工精度。

Using this compensation theory , the NC machine equipped the system of HuaZhong HNC-21 gets the expectant precision .

为了获得良好的CT图像，应该利用螺距来控制和减小螺旋CT图像的噪声。

In order to obtain superb image quality , efforts should be made to control and reduce CT noise by using pitch .

单纯增加螺距或使用360度线性内插（Wide）重建模式，都会引起CT图像实际层厚的增加，引起更大的容积效应影响。

Large helical pitch and wide reconstruction mode are subject to partial volume effect , resulting from the increase of scan slice thickness .

基于UG的变螺距螺旋面的研究与开发

Developing of helicoids with variable pitch based on UG platform

SBS改性沥青螺旋上料机的变径变螺距设计

Design of SBS modified asphalt helix transfer units with variable diameter and pitch

结论：对单层螺旋CT而言，CT模拟对肿瘤靶区的扫描应尽量使用薄层和小螺距（1.0~1.5）的成像参数。

Conclusion : While scanning the gross Target by Spiral CT , one should use thin slice and small pitch ( 1 ~ 1.5 ) .

采用约束优化方法&内点惩罚函数法，基于Matlab平台，对螺纹螺距进行了优化设计。

The optimal design of thread pitch is discussed based on subjected optimal method & internal penalty function method and Matlab platform .

AutoCAD扩充绘制变螺距螺旋面展开图命令

Command of the Development of the Variable Pitch Helical Blade for AutoCAD by Using Secondary Expansion of AutoCAD

本文使用CFD技术定量地预测了螺旋涡带的螺距和偏心率，探讨了由于螺旋涡带的形态变化对于脉动产生的影响。

The helical pitch and the eccentricity of the vortex rope can be quantitatively predicted by the CFD .

结论螺旋CT实际层厚与扫描层厚、螺距有密切关系，选择合适的扫描层厚及螺距对提高CT图像质量、减少扫描时间、减少病人接受的放射剂量均大有益处。

Conclusion CT scan with suitable scan slice and pitch can provide better quality of CT image , and decrease the examining time and the roentgen patient taken .

基于CFD技术，采用Fluent软件对变螺距诱导轮几何建模、选定边界条件等，进行其内部流场数值模拟计算。

Based on CFD technical and Fluent program , the fluid field about variable pitch inducer are numerical simulated .

目的评价双螺旋CT血管造影（SCTA）不同扫描层厚和螺距对门静脉成像质量的影响。

Objective To optimize parameters with double spiral computed tomographic angiography ( SCTA ) for visualization of portal veins .

采用小的螺距，和较大的螺距值来扫描可以提高CT图像质量并减少病人所接受的辐射剂量。

By adopting small pich and bigger pich value , the quality of CT images could be improved and the dose of radiation that patients take in would be reduced .

用圆偏光二向色性谱（CD）研究了这一聚合物的螺旋行为，主要包括螺距和螺旋方向。

The helicoidal behavior ( including mainly helix pitch and twist sense ) of this polymer was studied by means of circular dichroism ( CD ) .

本文介绍初始螺距比的敞水试验结果，文中除给出敞水性征曲线外，还给出了常用的Bp~（1/2）-δ设计图谱及简易设计图谱。

This paper presents the open water results at initial pitch setting . The conven-tional B_P ~ ( 1 / 2 ) - δ charts and the simplified design charts are also given .

由STM图象中我们能清晰地观察到螺旋结构的螺距与螺径。

From the STMimages , we could see clearly the helix pitch and helix diameter of helix structure .

本文分析了螺旋CT的噪声和纵向分辨率两个主要性能参数的性质：1.噪声与插值算法存在确定的函数关系，与螺距无关；

This article analyzes the two primary performance parameters ( noise , longitudinal resolution ) of spiral CT . The noise , independent of pitch , is a dependent function on applied interpolation algorithm .

结果表明CT低对比分辨力随着mA、kV、层厚、扫描时间、重建视野的增大而增大，随着扫描物体厚度、重建矩阵、螺距增大而减小；

The CT low-contrast resolution increased with mA , kV , slice thickness , scan time and FOV , and decreased with matrix , pitch and thickness of the scanned objective .

随着重建间隔改变，相应噪声水平的差异无显著性意义（P>0.05）。结论：与常规扫描相比，螺旋CT内插方式对噪声有一定影响，而螺距与重建间隔对噪声水平影响不明显。

Conclusion : In spiral CT , there is certain influence on image noise level with different linear interpolation techniques used , but there is no significant effect when pitches and reconstruction intervals are changed .

滚珠丝杠螺距误差前馈补偿法提高X-Y工作台定位精度的研究

Research on the Method of Lead - Screw Error Compensation for Improving X-Y Table Position Accuracy