Three-dimensional image reconstruction with Feldkamp, Davis, and Kress (FDK) algorithm is the most time consuming part in Micro-CT. The parallel algorithm based on the computer cluster is capable of accelerating image reconstruction speed; however, the hardware is very expensive. In this paper, using the most current graphics processing units (GPU), we present a method based on common unified device architecture (CUDA) for speeding up the Micro-CT image reconstruction process. The most time consuming filtering and back-projection parts of the FDK algorithm are parallelized for the CUDA architecture. The CUDA-based reconstruction speed and image qualities are compared with CPU results for the projecting data of the Micro-CT system. The results show that the 3D image reconstruction speed based on CUDA is ten times faster than the speed with CPU. In conclusion the FDK algorithm based on CUDA for Micro-CT can reconstruct the 3D image right after the end of data acquisition.

This paper proposes a method for predicting the reduced scattering coefficients of tissuesimulating phantoms or the desired amount of scatters for producing phantoms according to Mie scattering theory without measurements with other instruments. The concentration of the scatters TiO₂ particles is determined according to Mie theory calculation and added to transparent host epoxy resin to produce phantoms with different reduced scattering coefficients. Black India Ink is added to alter the absorption coefficients of the phantoms. The reduced scattering coefficients of phantoms are measured with single integrating sphere system. The results show that the measurements are in direct proportion to the concentration of TiO₂ and have identical with Mie theory calculation at multiple wavelengths. The method proposed can accurately determine the concentration of scatters in the phantoms to ensure the phantoms are qualified with desired reduced scattering coefficients at specified wavelength. This investigation should be possible to manufacture the phantom simply in reasonably accurate for evaluation of biomedical optical imaging systems.

A fluorescence molecular tomography system for in vivo tumor imaging is developed using a 748-nm continuous wave diode laser as an excitation source. A high sensitivity cooled charge-coupled device (CCD) camera with excitation and emission filters is utilized to obtain the excitation and fluorescence images. The laser beam performs fast raster scanning using a dual-axis galvanometric scanner. The accuracy of the laser spot position at the source window is within +-200 \mum. Based on the phantom experimental results, the spatial resolution is less than 1.7 mm, and the relative quantitation error is about 10%. In vivo imaging of a tumor-bearing nude mouse tagged with near-infrared dye demonstrates the feasibility of the system.