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New X-ray phase contrast imaging techniques without using synchrotron radiation confront a common problem from the negative effects of finite source sizes and limited spatial resolution. These negative effects swamp the fine phase contrast fringes and make them almost undetectable. In order to alleviate this problem, deconvolution procedures should be applied to the x-ray phase contrast images. In this study, four different deconvolution techniques were applied to experimental phase contrast images of a simple geometric phantom, including Weiner deconvolution method and Tikhonov regularization techniques with their Tikhonov matrix separately set as identity matrix, first order difference operator and second order difference operator. According to the free space propagation x-ray phase contrast imaging system, the source-to-sample distance (SS) of 200cm or 180cm was used with corresponding sample-to-detector distance (SD) of 20cm or 40cm. Image contrasts of 9.8%, 52.7%, 27.6% and 31.5% were separately obtained corresponding to above mentioned four techniques with SS/SD=200cm/20cm. For the second system setting (SS/SD=180cm/40cm), image contrasts of 11.9%, 112.8%, 66.3% and 76.5% were obtained separately. The Tikhonov regularization technique with Tikhonov matrix chosen as identity matrix obtains the highest contrast among all techniques. However, under this case, most noticeable artifacts and noise were introduced simultaneously. With full consideration on noise and artifacts, the Tikhonov matrix of second order difference operator will be the best choice for Tikhonov regularization method.

In vivo biomedical imaging using near-infrared light must overcome the effects of highly light scattering, which limit the spatial resolution and affect image quality. The high-resolution, sensitive and quantitative fluorescence imaging tool is an urgent need for the applications in small-animal imaging and clinical cancer research. A CT-analogous method for fluorescence molecular tomography (FMT) on small-animal-sized models is presented to improve the spatial resolution of FMT to a limit of several millimeters, depending on the size of the tissue region to be imaged. The method combines FMT physics with the filtered back-projection scheme for image reconstruction of the fan-beam computed tomography, based on the early-photon detection of time-resolved optical signals, and is suitable for two-dimensional (2D) imaging of small size biological models. By use of a normalized Born formulation for the inversion, the algorithm is validated using full time-resolved simulated data for 2D phantom that are generated from a hybrid finite-element and finite-time-difference photon diffusion modeling, and its superiority in the improvement of the spatial resolution is demonstrated by imaging different target-to-background contrast ratios.

We obtain absorption and scattering reconstructed images by incorporating a priori information of target location obtained from fluorescence diffuse optical tomography (FDOT) into the diffuse optical tomography (DOT). The main disadvantage of DOT lies in the low spatial resolution resulting from highly scattering nature of tissue in the near-infrared (NIR), but one can use it to monitor hemoglobin concentration and oxygen saturation simultaneously, as well as several other cheomphores such as water, lipids, and cytochrome-c-oxidase. Up to date, extensive effort has been made to integrate DOT with other imaging modalities such as MRI, CT, to obtain accurate optical property maps of the tissue. However, the experimental apparatus is intricate. In this study, DOT image reconstruction algorithm that incorporates a prior structural information provided by FDOT is investigated in an attempt to optimize recovery of a simulated optical property distribution. By use of a specifically designed multi-channel time-correlated single photon counting system, the proposed scheme in a transmission mode is experimentally validated to achieve simultaneous reconstruction of the fluorescent yield, lifetime, absorption and scattering coefficient. The experimental results demonstrate that the quantitative recovery of the tumor optical properties has doubled and the spatial resolution improves as well by applying the new improved method.