珠线式模板在Freehand超声图像快速标定中的应用  

Application of String-beads Phantom on Rapid 3-D Calibration Method for Freehand Ultrasound Image

作　　者：么娆[1] 陆文华[1] 胡盛斌[1] 贾慈力[1] 

机构地区：[1]上海工程技术大学航空运输学院,上海201620

出　　处：《机械工程学报》2016年第22期24-30,共7页Journal of Mechanical Engineering

基　　金：国家自然科学基金资助项目(61303098)

摘　　要：为了精确标定freehand超声图像坐标系与固定于超声探头上的跟踪设备坐标系间坐标转换关系,提出一种"Z"形珠线模板,由双层"Z"形棉线与精确定位的圆珠构成。定位珠能够引导用户将探头准确定位,即将定位珠全部收入图像视野中。计算定位珠在超声图像中成像点间距的比例关系,根据其相应的模板空间间距比例制定优化算法,校准用户拾取的图像坐标。应用同源点匹配算法得到超声图像平面坐标系与磁跟踪设备坐标系间的空间转换关系,从而实现2-D超声图像向3-D空间坐标系的定位转换。标定结果显示此方法与以往的标定方法相比:加快了标定速度,且标定精度与重建精度有所提高。试验采用磁定位方式进行探头的跟踪定位,此方法同样适用于其他定位方式。Purpose of Z-string-beads phantom design is to high precision calibration define the spatial relationship between the ultrasound（US） image plane and an external tracking device attached to the US probe.The phantom consists of accurately located beads and two layers of Z-string planar arrays.The beads can rapidly guide the user to accurate probe orientation for imaging when the US image plane is coincident with the beads plane.Then calculate all scales of every two distances between two neighboring imaging points of all beads in the scan plane,and select the special method to correct the manual coordinates of the imaging points according to the scales of distances between two beads in the phantom coordinate system.The calibration parameters are calculated by matching of homologous points in the image and the magnetic tracking device.Thus the 2-D US image can be converted into 3-D US coordinates.The results show that this method can improve the calibration efficiency the calibration procedure faster than other more complex methods and the calibration precision and reconstruction accuracy of the 3-D US system are similar to those.The material and the construction of the phantom are simplified and can reduce the interactions during the phantom imaging,so an efficient and rapid 3-D calibration method for freehand 2-D US is obtained.The calibration experiments are demonstrated with a magnetic locator,but the method could be suitable for other tracking devices.

关 键 词：超声图像标定 引导模板 自由式扫描 磁定位跟踪 三维定位 

分 类 号：TP399[自动化与计算机技术—计算机应用技术]