Development of a K-edge micro CT for the study of tumor angiogenesis in small animals

A new micro scanner CT for small animals - based on a couple of parallel quasi-monochromatic X-ray beams with different energies selectable - is under development at Physics Department of the University of Bologna. The aim of the study is the in vivo imaging of the tumor neo-angiogenesis pattern in an earlier diagnostic phase and the analysis of cancer growth and metastasis development in different tumor types on mice. The early diagnosis of cancer mainly relies on detection of precancerous changes, such as neo-angiogenesis. It represents one of the mechanisms of cancer development due to production of molecules in a very initial stage, stimulating new blood vessels creation, thus nourishing the cancer cells, which can continue to grow. As previously demonstrated(1), the imaging system based on dual energy quasi-monochromatic X-ray beams provides higher sensitivity in detecting low concentrations of iodine contrast medium if compared to traditional polychromatic Xray equipment. The K-edge dual energy radiology is a realistic candidate to recognize tumor neo-angiogenesis process in a very earlier stage, in which conventional systems are very poor in sensitivity. Moreover, the capability to select the energy of quasi-monochromatic beams enables the use of the Multi-Energy Quasi-Monochromatic technique. Tuning properly the energies allows maximizing the difference between linear absorption coefficients of healthy and pathological tissues increasing the contrast of pathologies. In order to optimize the contrast with this technique, one should know the X-ray energy regions where the absorption of healthy and pathological tissues eventually differs and that for each type of tumor under study. For this reason, the systematic X-ray characterization of many types of healthy and neoplastic human and mice tissues is in progress. The goal of this work is to obtain a catalog of liner attenuation coefficients of a variety of pathological tissues for respect to the healthy ones, finding any energy windows of radiological differentiation. In this paper, the theoretical methods are presented with development works and preliminary results.