面向大数据量的扩散光层析成像快速重建算法

Fast Reconstruction Scheme of Diffuse Optical Tomography for Dense Sampling Dataset

提高扩散光层析成像(DOT)重建质量的一个有效方法是增加光源和探测区域的采样密度。针对可提供大量测量数据的非接触式空间光DOT系统,研究了一种针对平板透射式模型的快速层析图像重建算法。该方法对源侧、探测侧两个平面以及成像平面均作了空间频率域编码,并基于组织的传递函数对参与重建的有效空间频率进行了选择,从而在不牺牲图像重建质量的情况下,极大地减少了重建时的计算量。而由空域变到空间频率域的过程,也降低了重建逆问题的病态性。数值模拟验证表明,在源-探对的数目为81×81的情况下,该算法重建一次图像的时间仅为10s左右,计算效率较常规的DOT成像算法提高了近400倍,且图像的重建量化率及噪声稳健性均明显优于常规DOT算法。

Increasing dense sampling of the illumination and detection offers an effective way of improving the image reconstruction performances of diffuse optical tomography （DOT）. We describe a fast tomographic image reconstruction scheme for a transmission measurement on a slab in the non-contact spatial light DOT providing large measurement data. The proposed method is carried out with the spatial-frequency encoding in both the measurement （source, detection） and the image spaces, and involves a strategy for selecting the useful spatial frequency based on the tissue transfer function. The method is expected to considerably reduce the calculation time for reconstruction whilst retain the quality of the reconstructed images. Additionally, the procedure of the spatial-frequency transform alleviates the ill-posedness of the inverse problem. Results from the simulated data show that it takes only 10 s to reconstruct one absorption image with the proposed method and the speed is more than 400 times faster than that with the conventional one for 81 × 81 source-detector pairs. Moreover, the proposed method shows a higher quantitativeness ratio and a superior anti-noise capability than the conventional one.