Purpose: Breast cancer is one of the leading causes of death for women worldwide. Early and accurate detection of malignancies is essential for improving the outcome of cancer treatments. Conventional X-ray imaging is based purely on contrasts of attenuation and, since no contrast difference between cancerous and glandular tissues is evident, the diagnosis is mainly based on the morphological characteristics of cancer. On the other hand, advanced imaging techniques allow the extraction of quantitative information. We aim to exploit a technique of spectral decomposition to quantify the difference in chemical composition between healthy and malignant dense tissues. Materials and Method: The study was carried out using a custom-made phantom, filled with water and containing inserts of plastic materials (polyethylene, nylon, polymethyl methacrylate, polyoxymethylene, polytetrafluoroethylene) that mimic the attenuation properties of breast tissues. An attempt to quantitatively describe breast mastectomy samples was also made. Imaging was performed at Elettra, the Italian synchrotron facility, using monochromatic beams of several energies in the breast CT imaging energy range (25-35 keV). 3D tomographic maps of attenuation coefficients were obtained by acquiring projections in a free space propagation phase-contrast setup and further processing them utilizing a phase retrieval filter, a procedure resulting in a significant noise reduction without loss of spatial resolution. Images were processed by a spectral decomposition algorithm, resulting in composition maps in terms of a selected pair of basis materials. Material choice matched the tissue range of interest inside the breast. Using a dedicated mathematical procedure, we managed to decouple the information about the material density and its chemical composition. Finally, a calibration allowed us to retrieve the effective atomic number associated with each reconstructed voxel. Results: The procedure allowed accurate discrimination of the chemical composition of considered inserts. The range of effective atomic numbers among the plastics matched the slight differences among tissues in the breast. Compared to previous studies, the present approach exhibits a much higher sensitivity in material discrimination, which was necessary for the quantitative characterization of breast mastectomy samples. Conclusions: The decoupling of the information about the chemical composition allows very accurate discrimination of similar tissues composing the breast. The proposed technique of spectral decomposition and decoupling allows a quantitative description of imaged sample composition, opening the possibility of significant contributions to a breast cancer diagnosis.
OL19 - A method for the quantitative discrimination of breast tissue chemical composition based on the spectral decomposition of x-ray tomographic breast images
G. Paternò;A. Taibi;
2021
Abstract
Purpose: Breast cancer is one of the leading causes of death for women worldwide. Early and accurate detection of malignancies is essential for improving the outcome of cancer treatments. Conventional X-ray imaging is based purely on contrasts of attenuation and, since no contrast difference between cancerous and glandular tissues is evident, the diagnosis is mainly based on the morphological characteristics of cancer. On the other hand, advanced imaging techniques allow the extraction of quantitative information. We aim to exploit a technique of spectral decomposition to quantify the difference in chemical composition between healthy and malignant dense tissues. Materials and Method: The study was carried out using a custom-made phantom, filled with water and containing inserts of plastic materials (polyethylene, nylon, polymethyl methacrylate, polyoxymethylene, polytetrafluoroethylene) that mimic the attenuation properties of breast tissues. An attempt to quantitatively describe breast mastectomy samples was also made. Imaging was performed at Elettra, the Italian synchrotron facility, using monochromatic beams of several energies in the breast CT imaging energy range (25-35 keV). 3D tomographic maps of attenuation coefficients were obtained by acquiring projections in a free space propagation phase-contrast setup and further processing them utilizing a phase retrieval filter, a procedure resulting in a significant noise reduction without loss of spatial resolution. Images were processed by a spectral decomposition algorithm, resulting in composition maps in terms of a selected pair of basis materials. Material choice matched the tissue range of interest inside the breast. Using a dedicated mathematical procedure, we managed to decouple the information about the material density and its chemical composition. Finally, a calibration allowed us to retrieve the effective atomic number associated with each reconstructed voxel. Results: The procedure allowed accurate discrimination of the chemical composition of considered inserts. The range of effective atomic numbers among the plastics matched the slight differences among tissues in the breast. Compared to previous studies, the present approach exhibits a much higher sensitivity in material discrimination, which was necessary for the quantitative characterization of breast mastectomy samples. Conclusions: The decoupling of the information about the chemical composition allows very accurate discrimination of similar tissues composing the breast. The proposed technique of spectral decomposition and decoupling allows a quantitative description of imaged sample composition, opening the possibility of significant contributions to a breast cancer diagnosis.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
