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Research

Medical X-ray Phase-Contrast and Dark-Field Imaging

 

A research focus of our group is the application of Talbot-Lau x-ray phase-contrast imaging on medical questions.

Several promising applications have been examined in recent years:

Mammography

The early detection of breast cancer via dark-field imaging has been a great aim in our group: in collaboration with the University hospital Erlangen the impact of clusters of superfine microcalcifications, as present in breast tumors, on the dark-field signal is considered. First results show great potential to improved early cancer diagnosis and better detectability of breast cancer through the exploitation of the phase contrast signal in addition to attenuation signal (See comparison of attenuation and dark-field contrast in figure 1: attenuation – top; dark-field – bottom). The latter provides supplementary information regarding calcifications within the tumor region).

Figure 1: Attenuation (top) and dark-field (bottom) images of a breast mastectomy specimen containing a tumor in the upper region. The dark-field provides supplementary information in the reconstructed signal, that is due to scattering in the event of clusters of superfine microcalcifications (see T. Michel et al., 2013, Phys. Med. Biol. 58, 2713).

 

Publications:

T. Michel et al., 2013, Phys. Med. Biol. 58, 2713 (https://iopscience.iop.org/article/10.1088/0031-9155/58/8/2713/pdf)

 

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 bee clearly seen in dark-field images (Figure 2).

Figure 2: Porktrotter with wooden splint. The wood cannot be seen in the attenuation image (top) and it can only hardly be seen in the differential phase-contrast image (middle), whereas it is well visible in the dark-field image.

 

Publications:

J. Rieger et al., 2017, JINST 12, P04018 (https://iopscience.iop.org/article/10.1088/1748-0221/12/04/P04018/pdf)

 

Lung imaging

The lung consists of small aveoli. 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 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. (see V. Ludwig et al., 2019, Phys. Med. Biol. 64, 065013)

 

Publications:

M. Seifert et al., 2018, Phys. Med. Biol. 63, 185010 (https://iopscience.iop.org/article/10.1088/1361-6560/aadafe/pdf)

V. Ludwig et al., 2019, Phys. Med. Biol. 64, 065013 (https://iopscience.iop.org/article/10.1088/1361-6560/ab051c/pdf)

 

 

For these applications, the feasibility of the setups is continuously improved with regard to acquisition velocity, stability, size of the field of view, dose application, high energy applications for large objects… In this context, new reconstruction and acquisition processes are developed, simulations are performed and setups are constructed.