用于光声层析成像的虚拟阵列探测及逆拉东变换(英文)

Virtual array detector and inverse Radon transform used for photoacoustic imaging

提出用固定孔径的换能器虚拟阵列探测器进行数据采集,该换能器只需对样品进行180°扫描。实验中,使用调QNd:YAG激光器作为光源,激光器输出激光波长为532nm,重复频率为10Hz,脉宽为7ns;使用非聚焦换能器进行光声信号探测,其接收面直径为6mm,中心频率为2.25MHz,接收到光声信号用逆拉东变换进行图像重建。以小白鼠的离体爪子作为成像对象,换能器由旋转电机控制并以2°作为旋转步长进行180°旋转扫描获取实验数据,运用逆拉东变换进行了图像重建。所重建的图像比较清晰地反映了爪子内部的骨骼分布。由此表明,逆拉东变换可以用于光声成像,并且实现了有限角度的光声成像。

A transducer with a fixed aperture is proposed as a virtual array detector to collect data. The transducer only needs to rotationally scan the sample 180 degrees. In the experiment, a Q switched Nd： YAG laser operating at 532 nm was used as the light source, with a pulse width of 7 ns and a repetition frequency of 10 Hz. An unfocused transducer with a central frequency of 2.25 MHz and a diameter of 6 mm was applied to detecting photoacoustic signals. And the image was reconstructed by processing the received photoacoustic sig nals with thc inverse Radon transform. An in vitro claw of a rat was used as the imaging object in the experi- ment and the data were obtained by rotating the transducer 180 degrees with a step of 2 degrees. The recon structed image from the inverse Radon transform clearly displays the bones within the claw. The results indicate that the inverse Radon transform can be used for photoacoustic reconstruction and limited view photoacoustic imaging is achieved with this method.