基于声学散射透镜的低成本光声断层成像方法

Low-cost photoacoustic tomography based on acoustic scattering lenses

光声断层成像需要使用换能器阵列及多通道系统,硬件成本较高,制约了其广泛应用.为降低成本,设计了一种基于声学散射透镜的光声断层成像方法,利用声学多重散射过程中的多路径效应达到增大探测阵列等效数值孔径的作用,从而减少信号探测过程所需换能器数量.通过数值模拟实验,首先分析了散射透镜格林函数的精确测量方法,随后利用四个散射透镜共同作用实现了高质量光声断层成像,并对影响成像质量的相关因素进行了具体研究.提出的散射透镜无须复杂制作工艺或特殊材料,系统只需四个超声换能器即可实现快速成像,可降低光声断层成像系统的硬件成本.

Photoacoustic tomography(PAT)is a hybrid biomedical imaging modality based on photoacoustic(PA)effect,it combines optical excitation with acoustic detection.As a no-ionizing and non-invasive technology,it can provide both structural and chemical informations in pre-clinical and clinical applications,including tumor diagnosis,drug delivering monitoring,little animal whole-body imaging,brain funtional imaging and so on.As a result,PAT has become one of the fastest growing imaging method in the past decade.One chanllenge that has continuously attracted the attention of researchers and engineerers in biomedical imaging field is to reduce the cost without degradation of performance.PAT system usually involves transducer array and multi-channels system,which lead to a high cost and bring limitations on widely application.As we know,with the known Green's function,multi-paths effect of multi-scattering can enlarge equivalent numerical aperture of the detecting array,and PA images can be reconstructed with much less transducers by time reversal algorithm.In this paper,we propose a PAT modality based on acoustic scattering lenses,which utilizing the multi-paths effect of multi-scattering.Firstly,a method for accurate of Green's function measuring is verified,quantitative studies indicate that,the accurracy of Green's function measuring can be improved by choosing the appropriate coherent gathering zones and increasing the number of transducers participated in Green's function measuring.Then,we demostrate that high-quality PA images can be achieved with four scattering lenses,while PA image quality can be improved by controlling the signal length.Scattering lens proposed in this paper needs not precision manufacture or special material,and just four transducers can accomplish quick imaging,with which PAT system cost can be reduced.