Effect of x-ray energy on the radiological image quality in propagation-based phase-contrast computed tomography of the breast

Purpose: Breast cancer is the most common cancer in women in developing and developed countries and is responsible for 15% of women’s cancer deaths worldwide. Conventional absorption-based breast imaging techniques lack sufficient contrast for comprehensive diagnosis. Propagation-based phase-contrast computed tomography (PB-CT) is a developing technique that exploits a more contrast-sensitive property of x-rays: x-ray refraction. X-ray absorption, refraction, and contrast-to-noise in the corresponding images depend on the x-ray energy used, for the same/fixed radiation dose. The aim of this paper is to explore the relationship between x-ray energy and radiological image quality in PB-CT imaging. Approach: Thirty-nine mastectomy samples were scanned at the imaging and medical beamline at the Australian Synchrotron. Samples were scanned at various x-ray energies of 26, 28, 30, 32, 34, and 60 keV using a Hamamatsu Flat Panel detector at the same object-to-detector distance of 6 m and mean glandular dose of 4 mGy. A total of 132 image sets were produced for analysis. Seven observers rated PB-CT images against absorption-based CT (AB-CT) images of the same samples on a five-point scale. A visual grading characteristics (VGC) study was used to determine the difference in image quality. Results: PB-CT images produced at 28, 30, 32, and 34 keV x-ray energies demonstrated statistically significant higher image quality than reference AB-CT images. The optimum x-ray energy, 30 keV, displayed the largest area under the curve ( AUCVGC ) of 0.754 (p = 0.009). This was followed by 32 keV (AUCVGC = 0.731, p ≤ 0.001), 34 keV (AUCVGC = 0.723, p ≤ 0.001), and 28 keV (AUCVGC = 0.654, p = 0.015). Conclusions: An optimum energy range (around 30 keV) in the PB-CT technique allows for higher image quality at a dose comparable to conventional mammographic techniques. This results in improved radiological image quality compared with conventional techniques, which may ultimately lead to higher diagnostic efficacy and a reduction in breast cancer mortalities.. © 2021 Society of Photo-Optical Instrumentation Engineers (SPIE).

Keywords

Contrast media, Computerized tomography, Mammary glands, Neoplasms, Diagnosis, Diagnostic techniques, Absorption, CAT scanning

Citation

Wan, S., Arhatari, B. D., Nesterets, Y. I., Mayo, S. C., Thompson, D., Fox, J., Kumar, B., Prodanovic, Z., Hausermann, D., Maksimenko, A. S., Hall, C. J., Dimmock, M. R., Pavlov, K. M., Lockie, D., Rickard, M., Gandomkar, Z., Alaleh, A., Vafa, E., Peele, A. G., Quiney, H. M., Lewis, S. J., Gureyev, T. E., Brennan, P. C., & Taba, S. T. (2021). Effect of x-ray energy on the radiological image quality in propagation-based phase-contrast computed tomography of the breast. Journal of Medical Imaging, 8(5), 052108. doi:10.1117/1.JMI.8.5.052108