Dual Energy X-ray Method for Kidney Stones and Atherosclerotic Plaques Structural Integrity Characterization

Abstract

Kidney stones and atherosclerotic plaques have an increasing rate worldwide. Although kidney stones are not life threatening, as atherosclerosis can be, they have the tense of reappearing after a period of time. Based on several studies it seems there is a correlation between these two diseases, as patients diagnosed with urolithiasis or nephrolithiasis appeared to have atherosclerotic plaques. Calcium oxalate and hydroxyapatite are the most frequently found minerals in stones. Calcium carbonate stones have also been present, but not in the same prevalence. Stones smaller than 5 mm are expected to pass on their own and thus no surgery is needed. However, each stone composition needs different treatment to be removed since they have different structural integrity among the same therapies. The very same minerals were found in spotty calcifications (<3 mm) in atherosclerotic plaques. Spotty calcifications, especially hydroxyapatite calcifications, act as an indicator of possible plaque rapture, while calcium oxalate is identified in stable plaques. Thus, the calcifications’ mineral differentiation will help the physicians to prevent myocardial infraction and stroke. To this aim, a dual-energy X-ray method was developed in this study. Simulation and experimental studies were conducted for the determination of the Calcium/Phosphorus mass ratio (mCa/mP). Monoenergetic and polyenergetic simulation studies were carried out for calcium oxalate, hydroxyapatite and calcium carbonate calcifications with thicknesses ranging from 0.5 to 3 mm, in order to find the optimized irradiation conditions. The experimental evaluation of the method was implemented with an X-ray tube combined with an energy integrating (imaging) detector. Based on the experimental results, for both kidney stones and atherosclerotic plaques, statistically significant difference was observed between the different types of minerals for thicknesses of 0.7 mm or higher.