PSI - Issue 33

Niki Martini et al. / Procedia Structural Integrity 33 (2021) 295–303 Martini/ Structural Integrity Procedia 00 (2021) 000–000

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3. Results and Discussion Based on monoenergetic simulation study results, the CV mCa/mP (%) ranged from its minimum value up to +20% of the minimum, when the low energy ranged from 40 to 50 keV and combined with all the examined high energies. Unfiltered spectra at 50 and 90 kVp for the low-and high-energy, respectively, were used in the polyenergetic study. The low energy spectrum was filtered with Aluminum. Even though Aluminum resulted in lower energies that those indicated by the monoenergetic study, the number of photons of the Aluminum filtered spectra was the highest compared the other filters applied to the low energy spectrum. As for the high energy spectrum, among all the filters examined, Gallium and Copper revealed a good compromise between mean energy and adequate number of photons (Martini et al. 2021). The thicknesses of Aluminum and Copper were indicated by the nonparametric statistical analysis implemented. Based on false negative (%), false positive (%) and overlap area (%) the irradiation conditions resulted in the minimization of these values were: (i) 50 kVp spectrum filtered with 3 mm Aluminum and (ii) 90 kVp spectrum filtered with 3 mm Copper, for the low-and high-energy, respectively. The low energy spectrum had a mean energy of 34 keV and the high energy spectrum had a mean energy of 72 keV. The constructed phantoms were immersed in the water tank and irradiated with the irradiation conditions mentioned above. In image were selected 20 regions of interest and thus the critical U value was 127 (Milton 1964). The averaged measured effective �� � ⁄ and the results of the Mann-Whitney U test of the examined thicknesses are presented in Table 2. Table 2. Averaged measured effective �� � ⁄ and the Mann-Whitney U test for all phantom thicknesses and mineral types. Hydroxyapatite thickness (mm) Averaged effective �� � ⁄ Mann-Whitney U test U value Hydroxyapatite Calcium carbonate Calcium oxalate Hydroxyapatite; Calcium carbonate Hydroxyapatite; Calcium oxalate Calcium carbonate; Calcium oxalate Critical value The Mann-Whitney U test results indicated that there are statistically signifficant differences (p < 0.05) between all mineral types for thickness of 1.5 mm or higher. When hydroxyapatite was to be differentated from calcium oxalate or calcium carbonate the thickness at which differentiation was achieved decreased to 0.7 mm. The characterization of the kidney/uteric stones or atherosclerotic plaque calcifications is of great importance sinse the knowledge of their composition reveals information of their structural integrity. According to the finfings the physicians can provide a better treatment planning for each patient in order to remove the kidney/uteric stones or prevent the patients from myocardial infraction and stroke incidents (Frochot et al. 2021, Eliahou et al. 2010, Jendeberg et al. 2017, Macfarlane 2015). The different minerals of which the kidney and uteric stones are composed need different treatment, as their structrural inegrity provide analogous resistanse in the treatment for their removal (Macfarlane 2015). In the same manner, the knowledge of the minerals of atherosclerotic plaques’ calcifications may lead to different medication prescription to the patient since the calcifications composed of hydroxyapatite make unstable the atherosclerotic plaque and can lead to plaque rapture (Feuchtner et al. 2019, Sakaguchi et al. 2016, Motoyama et al. 2007). 0.70 1.00 1.50 3.00 2.12 2.13 2.13 2.29 1.70 1.73 1.73 1.73 1.59 1.62 1.62 1.64 75 38 62 23 142 131 120 115 127 127 127 127 0 0 0 0

4. Conclusions In this study a dual-energy X-ray method was developed to characterize the minerals found in kidney/uteric stones and atherosclerotic plaques’ calcifications through the effective m Ca /m P . Monoenergetic and polyenergetic simulation studies, followed by experimental verification of the method, were carried out for calcium oxalate, hydroxyapatite