This study presents a comparison of the X-ray transmission through microsized and nanosized materials. For this purpose CuO nanoparticles, with 13.4 nm average grain size, and CuO microparticles, with a mean particle size of 56 μm, were incorporated separately to beeswax in a concentration of 5%. Results show that the transmission through the above material plates with microsized and nanosized CuO was almost the same for X-ray beams generated at 60 and 102 kV tube voltages. However, for the radiation beams generated at 26 and 30 kV tube voltages the X-rays are more attenuated by the nanostructured CuO plates by a factor of at least 14%. Results suggest that the difference in the low energy range may be due to the higher number of particles/gram in the plates designed with CuO nanoparticles and due to the grain size effect on the X-ray transmission.

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In this work a silicon PIN photodiode was employed in mammographic x-ray spectroscopy under clinical and nonclinical conditions. Measurements have been performed at a constant potential tungsten anode tube, adapted in this work with molybdenum filters to produce a beam like that used in mammography, and at a clinical equipment with a molybdenum anode tube by using an additional aluminum filtration. The corrected x-ray spectra were in full agreement with those generated by theoretical models published in the literature and agree well with those measured with a CdZnTe detector for tube voltages less than 30 kV. The half value layer and the relative exposure values calculated from the corrected silicon PIN photodiode spectra were in agreement with those measured with an ionization chamber. These results indicate that a silicon PIN photodiode are very suitable for mammographic x-ray spectroscopy. As an application, the voltage (kV) applied to mammographic x-ray equipment has been measured through the evaluation of the spectra high energy cut off. Uncertainties evaluated for the voltage values calculated from the measured spectra are less than 0.13% for voltages in the range 20-35 kV. The low uncertainties associated with the obtained results in this work point out that the method employed can be accurately used for calibration of noninvasive mammographic kVp meters.