OA246] A virtual study to determine the potential of dual-energy imaging for detectability of microcalcifications in breast screening

Abstract

Purpose Nowadays, the gold technique for screening and diagnosing the breast for lesions is the two-dimensional mammography. This technique experiences some limitations which appear when screening dense breasts. This calls for demand of new methods to improve the visualization of abnormalities. The aim of this work is to show how dual energy X-ray imaging technique may improve the visualization and detectability of abnormalities in mammographic examinations by removing the background clutter. The focus of this study is on improving the visualization of small calcifications. Methods The main part of the study is carried by use of two software tools. A dedicated LUCMRGen software application is used to design a computational breast phantom, comprised of an acrylic semi-cylinder container of thickness 45 mm and a diameter of 100 mm. The phantom was filled with 4970 acrylic spheres with radii between 1 mm and 8 mm. Simulated microcalcifications were designed as spheres with radiuses ranging from 0.3 to 1 mm, placed at different locations in the phantom. The assigned properties of the calcifications were hydroxy apatite, aluminium oxide, and calcium carbonate. Thereafter, mammographic X-ray images were generated using the XRAYImagingSimulator software tool. X-ray images were simulated with low energies from 18 to 21 keV, while the high energy beams were from 40 to 60 keV. Dual energy (DE) images were calculated by weighted subtraction of pairs of low and high energy images. For all simulations, the total incident air kerma at the surface of the model was set to 4 mGy. Dual-energy images were evaluated quantitatively by means of Contrast to Noise Ratio for each of the 16 DE combinations per calcification. Results Results showed that hydroxy apatite calcifications are best visible at combination of 20–40 keV; CaCO3 are best visible at combination of 21–45 keV, while Al2O3 are best visible at combination of 21–60 keV. A physical phantom, replica of the software one is under construction. Experimental validation is planned and results will be presented at the conference. Conclusions The dual energy imaging method offers the potential of improving the visualization of calcifications in mammography when the small calcifications are obscured by overlapping tissues.