Medical Physics

Medical X-ray phase-contrast and dark-field imaging

One main research focus of our X-ray grating interferometry group is the application of X-ray phase-contrast and dark-field imaging on medical questions. For that purpose, we continually optimize setup design and reconstruction algorithms, focusing on key aspects such as speed, stability, and dose application, to enhance performance and application-specific accuracy.

Several promising medical applications have been identified in recent years:

Mammography

The early detection of breast cancer by X-ray dark-field imaging is very promising: in collaboration with the University hospital Erlangen the impact of clusters of superfine microcalcifications (sizes about 5 – 10µm), as present in breast tumors, on the dark-field signal is examined. First results show great potential to improved early cancer diagnosis and better detectability of breast cancer through the additional obtained X-ray dark-field image (See comparison of attenuation and dark-field contrast in Figure 1). The X-ray dark-field image provides supplementary information regarding microcalcifications within the tumor region).

Figure 1: Attenuation (left) and dark-field (right) images of a breast mastectomy specimen containing a tumor. The dark-field provides supplementary information, that is due to scattering off clusters of superfine microcalcifications (From Ref. G. Anton et al., Grating-based darkfield imaging of human breast tissue, 2013, Zeitschrift für Med. Physik, Vol. 23, No. 3, p. 228-235. DOI: 10.1016/j.zemedi.2013.01.001 ; used under Creative Commons CC-BY 4.0 license).

Publications:

G. Anton et al., 2013, Zeitschrift f. Med. Phys., Vol. 23, No. 3, p. 228-235. DOI: 10.1016/j.zemedi.2013.01.001
T. Michel et al., 2013, Phys. Med. Biol. 58, 2713. DOI: 10.1088/0031-9155/58/8/2713
T. Rauch et al., 2020, Med. Phys., Vol. 47, No. 4, p. 1813. DOI: 10.1002/mp.14043

Foreign body detection

Since the dark-field is sensitive to fibrous and porous structures it shows great potential in the detection of foreign bodies in wounds. For example wood is hardly visible in common attenuation images, while it can be clearly seen in dark-field images (Figure 2).

Figure 2: Example for foreign body detection, from left to right: Photo of a gummy bear with a wooden toothpick, shown in the attenuation, the differential phase-contrast and the dark-field image. The wooden foreign body is best visible in the X-ray dark-field image. Credit: Andrea Zang.

Publications:

J. Rieger et al., 2017, JINST 12, P04018 DOI: 10.1088/1748-0221/12/04/p04018

Lung imaging

The lung consists of small alveoli. These small structures cause a strong scattering of the x-ray wavefront. Hence, the lung shows a high dark-field signal (Figure 3). The contrast of the lung to surrounding tissue is much higher in the dark-field image than in the attenuation image. Thus, pneumothoraxes, emphysema and further lung diseases can be earlier diagnosed with the help of X-ray dark-field imaging.

Figure 3: Images of a porcine lung. In the attenuation image (left) the heart shows a high contrast compared to the surrounding tissue whereas the lung is hardly visible. The lung is well visible in the dark-field image (right). In the middle the differential phase-contrast image can be seen. (From Ref. V. Ludwig et al., 2019, Phys. Med. Biol. 64, 065013. DOI: 10.1088/1361-6560/ab051c ; used under Creative Commons CC-BY 4.0 license)

Publications:

M. Seifert et al., 2018, Phys. Med. Biol. 63, 185010. DOI: 10.1088/1361-6560/aadafe
V. Ludwig et al., 2019, Phys. Med. Biol. 64, 065013. DOI: 10.1088/1361-6560/ab051c