Kim Hyun Keol, Netz Uwe J, Beuthan Jürgen, Hielscher Andreas H
Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
Opt Express. 2008 Oct 27;16(22):18082-101. doi: 10.1364/oe.16.018082.
In frequency-domain optical tomography (FDOT) the quality of the reconstruction result is affected by the choice of the source-modulation frequency. In general the accuracy of the reconstructed image should improve as the source-modulation frequency increases. However, this is only true for noise-free data. Experimental data is typically corrupted by noise and the accuracy is compromised. Assuming the validity of the widely used shot noise model, one can show that the signal-to-noise ratio (SNR) of the amplitude signal decreases with increasing frequency, whereas the SNR of the phase shift reaches peak values in the range between 400 MHz and 800 MHz. As a consequence, it can be assumed that there exists an optimal frequency for which the reconstruction accuracy would be highest. To determine optimal frequencies for FDOT, we investigate here the frequency dependence of optical tomographic reconstruction results using the frequency-domain equation of radiative transfer. We present numerical and experimental studies with a focus on small tissue volumes, as encountered in small animal and human finger imaging. Best reconstruction results were achieved in the 600-800 MHz frequency range.
在频域光学断层扫描（FDOT）中，重建结果的质量受源调制频率选择的影响。一般来说，随着源调制频率的增加，重建图像的准确性应该会提高。然而，这仅适用于无噪声数据。实验数据通常会受到噪声干扰，从而影响准确性。假设广泛使用的散粒噪声模型有效，可以证明幅度信号的信噪比（SNR）会随着频率增加而降低，而相移的信噪比在400 MHz至800 MHz范围内达到峰值。因此，可以假设存在一个使重建精度最高的最佳频率。为了确定FDOT的最佳频率，我们在此使用辐射传输的频域方程研究光学断层扫描重建结果的频率依赖性。我们重点针对小动物和人体手指成像中遇到的小组织体积进行了数值和实验研究。在600 - 800 MHz频率范围内获得了最佳重建结果。
