In vivo evaluation of Fe in the human skin and swins mice skin through the X-rays fluorescence technique

Recent technological improvements allow the method of in vivo XRF to supply useful sensibility for diagnostics or monitoring in biomedical applications. In cases of hereditary sanguine disorders as the β-Thalassaemia or a genetic disorder like Haemochromatosis, there is a high concentration of elements as Fe, Zn and Cu in the skin and internal organs, due to the treatment of those abnormalities or due to the own dysfunction caused by the disease. The levels of Fe related to the patient bearers of the β-Thalassaemia are determined, at the moment, measuring a protein in the sanguine current, called ferritin. The monitoring of the protein is ineffective in several situations, such as when the patient suffers any disturbance of health. Nowadays, the main forms of measuring the levels of those metals through hepatic storage are the biopsy of the liver, that is invasive and potentially dangerous, presenting a rate of mortality of 0,1%, and through magnetic susceptibilities that employs a quantum superconductor, which is highly expensive and there are only three main world medical centers with this equipment. This work investigates the use of a Si PIN-diode detector and a 238Pu source (13 and 17 keV; 13%; 95.2 mCi; 86y) for the measurement of Fe skin levels compatible with those associated to the disease β-Thalassaemia. XRF spectra were analyzed using a set of AXIL-WinQXAS programs elaborated and disseminated by the IAEA. The determination coefficient of the calibration model (sensitivity curve) was 0.97. Measurements on skin phantoms containing concentrations of Fe in the range from 15 to 150 parts per million (ppm), indicate that we are able to detect Fe at levels of the order of 13 ppm, using monitoring periods of 50 seconds and skin entrance dose less than 10 mSv. The literature reports skin Fe levels from 15.0 to 60.0 ppm in normal persons and from 70 to 150 ppm in thalassaemic patients. So, the employed methodology allows the in vivo measurement of the skin Fe concentration in wanted levels. (author)