Refraction beats attenuation in breast CT

TL;DR

This study demonstrates that grating interferometry-based CT provides better contrast and dose efficiency for breast imaging than traditional attenuation-based CT, even at clinical dose levels.

Contribution

It is the first to show that refraction contrast via grating interferometry improves breast CT imaging quality and dose efficiency in a clinical setting.

Findings

Refraction contrast outperforms attenuation in tissue contrast-to-noise ratio.

GI-CT achieves superior image quality at clinical dose levels.

Refraction imaging reduces radiation dose while maintaining diagnostic quality.

Abstract

For a century, clinical X-ray imaging has visualised only the attenuation properties of tissue, which fundamentally limits the contrast, particularly in soft tissues like the breast. Imaging based on refraction can overcome this limitation, but so far has been constrained to high-dose ex-vivo applications or required highly coherent X-ray sources, like synchrotrons. It has been predicted that grating interferometry (GI) could eventually allow computed tomography (CT) to be more dose-efficient. However, the benefit of refraction in clinical CT has not been demonstrated so far. Here we show that GI-CT is more dose-efficient in imaging of breast tissue than conventional CT. Our system, based on a 70kVp X-ray tube source and commercially available gratings, demonstrated superior quality, in terms of adipose-to-glandular tissue contrast-to-noise ratio (CNR), of refraction-contrast compared to the attenuation images. The fusion of the two modes of contrast outperformed conventional CT for spatial resolutions better than 263{\mu}m and an average dose to the breast of 16mGy, which is in the clinical breast CT range. Our results show that grating interferometry can significantly reduce the dose, while maintaining the image quality, in diagnostic breast CT. Unlike conventional absorption-based CT, the sensitivity of refraction-based imaging is far from being fully exploited, and further progress will lead to significant improvements of clinical X-ray CT.