Nuster Robert, Paltauf Günther
Department of Physics, University of Graz, 8010 Graz, Austria.
J Imaging. 2019 Jan 11;5(1):15. doi: 10.3390/jimaging5010015.
Ultrasound sensor arrays for photoacoustic tomography (PAT) are investigated that create line projections of the pressure generated in an object by pulsed light illumination. Projections over a range of viewing angles enable the reconstruction of a three-dimensional image. Two line-integrating arrays are compared in this study for the in vivo imaging of vasculature, a piezoelectric array, and a camera-based setup that captures snapshots of the acoustic field emanating from the sample. An array consisting of 64 line-shaped sensors made of piezoelectric polymer film, which was arranged on a half-cylindrical area, was used to acquire spatiotemporal data from a human finger. The optical setup used phase contrast to visualize the acoustic field generated in the leg of a mouse after a selected delay time. Time-domain back projection and frequency-domain back propagation were used for image reconstruction from the piezoelectric and optical data, respectively. The comparison yielded an about threefold higher resolution for the optical setup and an about 13-fold higher sensitivity of the piezoelectric array. Due to the high density of data in the camera images, the optical technique gave images without streak artifacts, which were visible in the piezo array images due to the discrete detector positions. Overall, both detection concepts are suited for almost real-time projection imaging and three-dimensional imaging with a data acquisition time of less than a minute without averaging, which was limited by the repetition rate of the laser.
对用于光声断层扫描（PAT）的超声传感器阵列进行了研究，该阵列可生成由脉冲光照射在物体中产生的压力的线投影。在一系列视角上的投影能够重建三维图像。在本研究中，比较了两种用于血管系统体内成像的线积分阵列，一种是压电阵列，另一种是基于相机的装置，用于捕捉样品发出的声场的快照。使用由压电聚合物薄膜制成的64个线形传感器组成的阵列，该阵列布置在半圆柱形区域上，用于从人体手指获取时空数据。光学装置使用相衬法在选定的延迟时间后可视化在小鼠腿部产生的声场。分别使用时域反投影和频域反向传播从压电数据和光学数据进行图像重建。比较结果表明，光学装置的分辨率高出约三倍，压电阵列的灵敏度高出约13倍。由于相机图像中的数据密度高，光学技术生成的图像没有条纹伪影，而在压电阵列图像中由于探测器位置离散而可见条纹伪影。总体而言，两种检测概念都适用于几乎实时的投影成像和三维成像，数据采集时间不到一分钟且无需平均，这受到激光重复率的限制。
