Joint use of early and quasi-continuous wave photons in time-gated tomographic imaging.

摘要

Measurement of early-photons (EP) from a rapid pulsed laser source has been shown to improve resolution versus continuous wave (CW) systems for diffuse optical tomography (DOT) and fluorescence mediated tomography (FMT). While EP significantly improved the image resolution, the quantitative accuracy and minimum detection are relatively low compared to CW given that EP measurements require temporal rejection of around 99% of transmitted photons. In this thesis, a 'joint data set' image reconstruction approach was developed, the goal of which was to produce an image that retained the resolution and signal and noise advantages of both EP and CW data sets, respectively. In this approach, CW data was first tomographically reconstructed to produce a low resolution but relatively highly quantitatively accurate image, and then this intermediate image was refined with EP data to yield a higher resolution image. We testing the approach with simulated EP and CW measurements of fluorescent objects and investigated the resolution, quantitative accuracy and detection sensitivity of images obtained using the joint data set approach. We demonstrated that it was possible to produce reconstructed images that retained approximately 74% of the resolution of EP images and around 80% of the quantitative accuracy of CW images, respectively. However, the joint data set approach did not significantly improve the detection sensitivity limitation of EP data sets.