Dual energy-based quantification method for determination of breast microcalcification types

Abstract

The purpose of this study is to distinguish and characterize breast microcalcification types (benign and malignant) non-invasively using photon-counting spectral mammography. In this study, a photon-counting spectral mammography system was simulated using Geant4 application for tomographic emission (GATE) tool. Based on the photon-counting detector, dual-energy images were obtained using two energy bins. Calcium oxalate and calcium hydroxyapatite were used for benign and malignant microcalcifications, respectively. As a quantitative characteristic evaluation for two types of microcalcification related to etiology, an analytical model was implemented for the determination of the calcium/phosphorus mass ratio (mCa/mP) based on the dual-energy method. In the chemical composition of each microcalcification, the calcium hydroxyapatite has a phosphate substance, and calcium oxalate has an oxalate substance. The thicknesses of the calcium oxalate corresponding to calcium hydroxyapatite were calculated to preserve equal photon beam attenuation. The results indicate a higher mass ratio value in the case of malignant microcalcifications when compared with that in the case of benign ones. Even when the breast thickness increased up to 5 cm, the difference in the mass ratio exhibited a constant tendency. By excluding the effect on x-ray attenuation properties, we confirmed that malignant and benign microcalcifications were quantitatively distinguished based only on the mineral properties of the chemical composition. In conclusion, this study provides quantitative and objective indicators, a non-invasive discrimination method of two types of microcalcifications associated with pathology. We also expect to reduce the frequency of biopsies by improving the accuracy of early diagnosis in mammography.