Breast phantom design for X-ray phase-contrast imaging

Abstract

Breast cancer is one of the most diffuse diseases and its incidence rate is increasing. Mammography is the gold standard exam for screening breast cancer. Nevertheless, to provide better conditions for visualization and detection of tumors, in particular to young women, techniques exploiting the X-ray phase contrast to generate images have been studied and proposed for clinical use. As every imaging modality clinically implemented, the capabilities and limitations of an X-ray phase-contrast system dedicated to breast imaging should be evaluated by a phantom. Although for mammography, there are several commercial phantoms, for tomographic X-ray phase-contrast imaging systems dedicated to breast screening, they are absent. Therefore, this study aimed to design a breast phantom for application in phase-contrast computed tomography (PC-CT) imaging. A breast phantom dedicated to X-ray phase-contrast imaging was designed. The phantom has a cylindrical shape and is composed by PMMA, to mimic the breast of a young woman, with some inserts filled with tissue substitutes to normal and pathological breast tissues, such as ethanol and glycerol. These materials were chosen due to the similarity in the attenuation and scattering properties of normal and pathological human breast tissues. A comparison between tomographic X-ray absorption imaging and tomographic X-ray phase-contrast imaging showed a significant increase in edges definition, even with materials with similar attenuation properties. The results of this work reinforce the need for dedicated phantoms to exploit the features of each imaging modality more realistic. In particular, the breast phantom–designed breast screening by PC-CT allows exploiting the features of this new imaging modality.