高分辨率快速数字化光声CT乳腺肿瘤成像  

High resolution fast digital photoacoustic CT for breast cancer diagnosis

作　　者：向良忠[1] 邢达[1] 郭华[1] 杨思华[1] 

机构地区：[1]华南师范大学激光生命科学研究所暨激光生命科学教育部重点实验室,广州510631

出　　处：《物理学报》2009年第7期4610-4617,共8页Acta Physica Sinica

基　　金：教育部长江学者与创新团队发展计划(批准号:IRT0829);国家自然科学基金面上项目(批准号:30627003;30870676);广东省自然科学基金(批准号:7117865)资助的课题~~

摘　　要：提出了一种基于聚焦线性阵列探测器的快速光声计算机断层成像技术(光声CT).在光声二维图像重建中,根据阵列探测器机械扫描和电子扫描相结合的组合扫描模式,提出了改进的有限场滤波反投影重建算法.一方面该算法适合多元探测器旋转扫描模式,另一方面探测器的指向性函数作为反投影的权重因子提高了系统的横向分辨率.同时,该成像系统还利用柱面声透镜实现Z轴方向上的聚焦扫描以实现三维层析成像.实验中,这套成像系统空间分辨率达到0.2 mm,Z轴方向分辨率为1.5 mm,扫描一幅二维图像仅需150 s,得到了高分辨率的微血管网络光声二维图像和乳腺肿瘤的三维层析图像.实验证明,该成像系统可提供快速、高分辨率的光声图像,从而为光声技术在肿瘤的早期诊断和治疗监控提供了坚实的技术基础.Photoacoustic imaging combines advantages of both ultrasound imaging and optical imaging to provide high ultrasonic resolution and high optical contrast in noninvasive medical images. A photoacoustic computer tomography （PCT） system with a focused digital phased array transducer is proposed. In particular each element of the transducer array has a thin cylindrical ultrasonic lens to select 2D image plane and suppress the out - of- plane signals to realize photoaconstic computed tomography. A fast full - view photoacoustic imaging system for visualizing tissue structures using a linear transducer array with combined scan, whies; detects photoacoustic signals by combined electronic and mechanical scanning. An improved limited - field filtered back projection algorithm with directivity factors was applied to reconstruct the optical absorption distribution and further improve the lateral resolution. In the experiment, the spatial resolution of this imaging system is determined as 0.2 mm, and the slice resolution of Z axis is 1.5 mm. Mechanical step scanning was performed, leading to a measurement time of 6.4 seconds per position, and a total scan duration of 150 seconds to obtain the two-dimensional photoacoustic image. High spatial resolution of 2D photoacoustic vascular image and quasi-3D photoacoustic CT for breast cancer imaging are achicned. The experimental results demonstrate that this method and imaging system can realize the high resolution photoacoustic tomography wtich can be applied to noninvasive detection of early breast cancer.

关 键 词：光声CT 有限场滤波反投影算法 声透镜聚焦 乳腺肿瘤检测 

分 类 号：TH774[机械工程—仪器科学与技术] TP391.41[机械工程—精密仪器及机械]