The influence of the image reconstruction in relative quantification in SPECT/PET/CT animal

The objective of this study is to evaluate the spatial resolution of the equipment SPECT/PET/CT animal to different reconstruction methods and the influence of this parameter in the mouse dosimetry C57BL6, aimed at development of new radiopharmaceuticals for use in humans. CT and SPECT images were obtained from a simulator composed of four spheres of different diameters (d), which simulate captating lesions by the equipment FLEX ™ Triumph ™ Pre-Clinical Imaging System used for preclinical studies in the Hospital Universitario (HU/UFRJ). In order to simulate a real study, the total volume of the simulator (body) was filled with a solution of 99mTc diluted in water and the spheres were filled with concentrations four time higher than the body of the simulator. From the gross SPECT images it was used filtered backprojection method (FBP) with application of different filters: Hamming, Hann and Ramp, ranging the cutoff frequencies. The resolution of the equipment found in the study was 9.3 to 9.4 mm, very below the value provided by the manufacturer of 1.6mm. Thus, the protocol for mice can be optimized as being the FBP reconstruction method of Hamming filter, cutoff of 0.5 to yield a resolution from 9.3 to 9.4mm. This value indicates that captating regions of diameter below 9.3 mm are not properly quantified