X-Ray Fluorescence Microtomography in Biological Applications

Abstract

Since tomographic techniques were developed, X-ray transmission tomography has been used in nondestructive testing for investigating the internal structure of samples, and with the advent of intense synchrotron radiation sources the resolution of the tomography was improved into μm regime. Other complementary tomographic techniques have been developed based on the detection of the scattered (Golosio et al., 2003) and fluorescent photons (Cesareo & Mascarenhas, 1989.) in other to get some properties that also depend upon the distribution of individual elements within the sample. The X-ray fluorescence associate with tomographic techniques can supply important information of the sample chemical properties and to produce high contrast in conditions where transmission tomography is not adjusted. One of the drawbacks of X-ray fluorescence tomography is the reconstruction calculation that is more complex than X-ray transmission tomography's algorithm (Hogan et al., 1991). Hogan et al. proposed adapting one of the algorithms used in X-ray transmission tomography (Brunetti & Golosio, 2001). The simplest algorithm is based on the classical back projection algorithm used In X-ray transmission tomography. An algorithm more accurate applies corrections for absorption before and after the fluorescence point. In recent years, there has been growing interest in understanding the exact role played by trace elements in several diseases. The biological function of some metal ions in combination with an investigation of element distribution patterns in malignant and in normal human tissues of cancer patients can give some indication of the effect of metal ions on carcinogenesis (Raju et al., 2006). Both excess and deficiency of trace elements have been associated with many diseases including cancer. Even though extensive work has been carried out to find an association between trace elements and cancer, and to understand the mechanisms involved in carcinogenesis, no definite conclusions are drawn so far (Rocha et al., 2007). Although trace elements Fe, Cu, and Zn are extremely common, assessment of their amounts is crucial for disease diagnostics. Both excess and deficiency of trace elements have