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  1. Article ; Online: Correction for X-ray Scatter and Detector Crosstalk in Dark-field Radiography.

    Urban, Theresa / Noichl, Wolfgang / Engel, Klaus Juergen / Koehler, Thomas / Pfeiffer, Franz

    IEEE transactions on medical imaging

    2024  Volume PP

    Abstract: Dark-field radiography, a new X-ray imaging method, has recently been applied to human chest imaging for the first time. It employs conventional X-ray devices in combination with a Talbot-Lau interferometer with a large field of view, providing both ... ...

    Abstract Dark-field radiography, a new X-ray imaging method, has recently been applied to human chest imaging for the first time. It employs conventional X-ray devices in combination with a Talbot-Lau interferometer with a large field of view, providing both attenuation and dark-field radiographs. It is well known that sample scatter creates artifacts in both modalities. Here, we demonstrate that also X-ray scatter generated by the interferometer as well as detector crosstalk create artifacts in the dark-field radiographs, in addition to the expected loss of spatial resolution. We propose deconvolution-based correction methods for the induced artifacts. The kernel for detector crosstalk is measured and fitted to a model, while the kernel for scatter from the analyzer grating is calculated by a Monte-Carlo simulation. To correct for scatter from the sample, we adapt an algorithm used for scatter correction in conventional radiography. We validate the obtained corrections with a water phantom. Finally, we show the impact of detector crosstalk, scatter from the analyzer grating and scatter from the sample and their successful correction on dark-field images of a human thorax.
    Language English
    Publishing date 2024-03-07
    Publishing country United States
    Document type Journal Article
    ZDB-ID 622531-7
    ISSN 1558-254X ; 0278-0062
    ISSN (online) 1558-254X
    ISSN 0278-0062
    DOI 10.1109/TMI.2024.3374974
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Prophylactic Trimethoprim-Sulfamethoxazole for Allogeneic Hematopoietic Stem Cell Transplant Recipients During the Pre-engraftment Period.

    Gaffney, Kelly J / Urban, Theresa A / Lucena, Mariana / Rybicki, Lisa / Majhail, Navneet S / Mossad, Sherif Beniameen

    Clinical hematology international

    2023  Volume 5, Issue 2-3, Page(s) 65–70

    Abstract: Background: Our institution has used trimethoprim-sulfamethoxazole (TMP-SMX) as the antibacterial agent of choice for infection prophylaxis during the pre-engraftment period in the allogeneic transplant (allo-HCT) population.: Methods: This ... ...

    Abstract Background: Our institution has used trimethoprim-sulfamethoxazole (TMP-SMX) as the antibacterial agent of choice for infection prophylaxis during the pre-engraftment period in the allogeneic transplant (allo-HCT) population.
    Methods: This retrospective, single center study was developed to compare the safety of that antibacterial prophylaxis to fluoroquinolones in allo-HCT. The primary endpoint was time to neutrophil engraftment.
    Results: A total of 366 patients were reviewed (TMP-SMX n = 332, fluoroquinolone n = 34). No difference in days to neutrophil engraftment was found (median 15 versus 16 days, p = 0.62). Hyperkalemia was more common in the TMP-SMX cohort (32.2% versus 14.7%, p = 0.035); this did not contribute to a higher rate of agent discontinuation or arrhythmia. There was no significant difference in the incidence of neutropenic fever; however, those in the TMP-SMX cohort were more likely to have microbiologically confirmed bacteremia (24.1% versus 8.8% respectively, p = 0.043). There was no significant difference in infections. No long-term implication of prophylactic antibacterial agent selection was observed in terms of graft-versus-host-disease, underlying disease relapse, or mortality.
    Conclusion: The use of TMP-SMX was associated with a higher likelihood of bacteremia and hyperkalemia; however, this did not result in increased hospital stay, escalation of care, or mortality. The use of TMP-SMX for prophylaxis during the pre-engraftment period for allo-HCT recipients is safe and effective.
    Language English
    Publishing date 2023-02-04
    Publishing country United States
    Document type Journal Article
    ISSN 2590-0048
    ISSN (online) 2590-0048
    DOI 10.1007/s44228-023-00029-7
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  3. Article ; Online: Dark-Field Chest Radiography of Combined Pulmonary Fibrosis and Emphysema.

    Gassert, Florian T / Urban, Theresa / Pfeiffer, Daniela / Pfeiffer, Franz

    Radiology. Cardiothoracic imaging

    2022  Volume 4, Issue 4, Page(s) e220085

    Abstract: Supplemental material is available for this article. ...

    Abstract Supplemental material is available for this article.
    Language English
    Publishing date 2022-08-18
    Publishing country United States
    Document type Journal Article
    ISSN 2638-6135
    ISSN (online) 2638-6135
    DOI 10.1148/ryct.220085
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  4. Article ; Online: X-Ray Dark-Field Signal Reduction Due to Hardening of the Visibility Spectrum.

    De Marco, Fabio / Andrejewski, Jana / Urban, Theresa / Willer, Konstantin / Gromann, Lukas / Koehler, Thomas / Maack, Hanns-Ingo / Herzen, Julia / Pfeiffer, Franz

    IEEE transactions on medical imaging

    2024  Volume 43, Issue 4, Page(s) 1422–1433

    Abstract: X-ray dark-field imaging enables a spatially-resolved visualization of ultra-small-angle X-ray scattering. Using phantom measurements, we demonstrate that a material's effective dark-field signal may be reduced by modification of the visibility spectrum ... ...

    Abstract X-ray dark-field imaging enables a spatially-resolved visualization of ultra-small-angle X-ray scattering. Using phantom measurements, we demonstrate that a material's effective dark-field signal may be reduced by modification of the visibility spectrum by other dark-field-active objects in the beam. This is the dark-field equivalent of conventional beam-hardening, and is distinct from related, known effects, where the dark-field signal is modified by attenuation or phase shifts. We present a theoretical model for this group of effects and verify it by comparison to the measurements. These findings have significant implications for the interpretation of dark-field signal strength in polychromatic measurements.
    MeSH term(s) X-Rays ; Tomography, X-Ray Computed/methods ; Radiography ; Models, Theoretical ; Phantoms, Imaging
    Language English
    Publishing date 2024-04-03
    Publishing country United States
    Document type Journal Article
    ZDB-ID 622531-7
    ISSN 1558-254X ; 0278-0062
    ISSN (online) 1558-254X
    ISSN 0278-0062
    DOI 10.1109/TMI.2023.3337994
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Book ; Online ; Thesis: Dark-field Chest Radiography – Image Artifacts and COPD Assessment

    Urban, Theresa [Verfasser] / Pfeiffer, Franz [Akademischer Betreuer] / Rückert, Daniel [Gutachter] / Pfeiffer, Franz [Gutachter]

    2023  

    Author's details Theresa Urban ; Gutachter: Daniel Rückert, Franz Pfeiffer ; Betreuer: Franz Pfeiffer
    Keywords Medizin, Gesundheit ; Medicine, Health
    Subject code sg610
    Language English
    Publisher Universitätsbibliothek der TU München
    Publishing place München
    Document type Book ; Online ; Thesis
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  6. Article ; Online: Correction for Mechanical Inaccuracies in a Scanning Talbot-Lau Interferometer.

    Noichl, Wolfgang / De Marco, Fabio / Willer, Konstantin / Urban, Theresa / Frank, Manuela / Schick, Rafael / Gleich, Bernhard / Hehn, Lorenz / Gustschin, Alex / Meyer, Pascal / Koehler, Thomas / Maack, Ingo / Engel, Klaus-Jurgen / Lundt, Bernd / Renger, Bernhard / Fingerle, Alexander / Pfeiffer, Daniela / Rummeny, Ernst / Herzen, Julia /
    Pfeiffer, Franz

    IEEE transactions on medical imaging

    2024  Volume 43, Issue 1, Page(s) 28–38

    Abstract: Grating-based X-ray phase-contrast and in particular dark-field radiography are promising new imaging modalities for medical applications. Currently, the potential advantage of dark-field imaging in early-stage diagnosis of pulmonary diseases in humans ... ...

    Abstract Grating-based X-ray phase-contrast and in particular dark-field radiography are promising new imaging modalities for medical applications. Currently, the potential advantage of dark-field imaging in early-stage diagnosis of pulmonary diseases in humans is being investigated. These studies make use of a comparatively large scanning interferometer at short acquisition times, which comes at the expense of a significantly reduced mechanical stability as compared to tabletop laboratory setups. Vibrations create random fluctuations of the grating alignment, causing artifacts in the resulting images. Here, we describe a novel maximum likelihood method for estimating this motion, thereby preventing these artifacts. It is tailored to scanning setups and does not require any sample-free areas. Unlike any previously described method, it accounts for motion in between as well as during exposures.
    Language English
    Publishing date 2024-01-02
    Publishing country United States
    Document type Journal Article
    ZDB-ID 622531-7
    ISSN 1558-254X ; 0278-0062
    ISSN (online) 1558-254X
    ISSN 0278-0062
    DOI 10.1109/TMI.2023.3288358
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  7. Book ; Online: Optimizing Convolutional Neural Networks for Chronic Obstructive Pulmonary Disease Detection in Clinical Computed Tomography Imaging

    Dorosti, Tina / Schultheiss, Manuel / Hofmann, Felix / Thalhammer, Johannes / Kirchner, Luisa / Urban, Theresa / Pfeiffer, Franz / Schaff, Florian / Lasser, Tobias / Pfeiffer, Daniela

    2023  

    Abstract: We aim to optimize the binary detection of Chronic Obstructive Pulmonary Disease (COPD) based on emphysema presence in the lung with convolutional neural networks (CNN) by exploring manually adjusted versus automated window-setting optimization (WSO) on ... ...

    Abstract We aim to optimize the binary detection of Chronic Obstructive Pulmonary Disease (COPD) based on emphysema presence in the lung with convolutional neural networks (CNN) by exploring manually adjusted versus automated window-setting optimization (WSO) on computed tomography (CT) images. 7,194 CT images (3,597 with COPD; 3,597 healthy controls) from 78 subjects (43 with COPD; 35 healthy controls) were selected retrospectively (10.2018-12.2019) and preprocessed. For each image, intensity values were manually clipped to the emphysema window setting and a baseline 'full-range' window setting. Class-balanced train, validation, and test sets contained 3,392, 1,114, and 2,688 images. The network backbone was optimized by comparing various CNN architectures. Furthermore, automated WSO was implemented by adding a customized layer to the model. The image-level area under the Receiver Operating Characteristics curve (AUC) [lower, upper limit 95% confidence] was utilized to compare model variations. Repeated inference (n=7) on the test set showed that the DenseNet was the most efficient backbone and achieved a mean AUC of 0.80 [0.76, 0.85] without WSO. Comparably, with input images manually adjusted to the emphysema window, the DenseNet model predicted COPD with a mean AUC of 0.86 [0.82, 0.89]. By adding a customized WSO layer to the DenseNet, an optimal window in the proximity of the emphysema window setting was learned automatically, and a mean AUC of 0.82 [0.78, 0.86] was achieved. Detection of COPD with DenseNet models was improved by WSO of CT data to the emphysema window setting range.
    Keywords Electrical Engineering and Systems Science - Image and Video Processing ; Computer Science - Computer Vision and Pattern Recognition ; Computer Science - Machine Learning
    Subject code 006
    Publishing date 2023-03-13
    Publishing country us
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article: Dark-field X-ray imaging for the assessment of osteoporosis in human lumbar spine specimens.

    Gassert, Florian T / Urban, Theresa / Kufner, Alexander / Frank, Manuela / Feuerriegel, Georg C / Baum, Thomas / Makowski, Marcus R / Braun, Christian / Pfeiffer, Daniela / Schwaiger, Benedikt J / Pfeiffer, Franz / Gersing, Alexandra S

    Frontiers in physiology

    2023  Volume 14, Page(s) 1217007

    Abstract: Background: ...

    Abstract Background:
    Language English
    Publishing date 2023-07-17
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2564217-0
    ISSN 1664-042X
    ISSN 1664-042X
    DOI 10.3389/fphys.2023.1217007
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  9. Article ; Online: X-ray Dark-Field Chest Imaging: Qualitative and Quantitative Results in Healthy Humans.

    Gassert, Florian T / Urban, Theresa / Frank, Manuela / Willer, Konstantin / Noichl, Wolfgang / Buchberger, Philipp / Schick, Rafael / Koehler, Thomas / von Berg, Jens / Fingerle, Alexander A / Sauter, Andreas P / Makowski, Marcus R / Pfeiffer, Daniela / Pfeiffer, Franz

    Radiology

    2023  Volume 306, Issue 2, Page(s) e229037

    Language English
    Publishing date 2023-01-23
    Publishing country United States
    Document type Published Erratum
    ZDB-ID 80324-8
    ISSN 1527-1315 ; 0033-8419
    ISSN (online) 1527-1315
    ISSN 0033-8419
    DOI 10.1148/radiol.229037
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  10. Article ; Online: X-ray dark-field chest radiography: a reader study to evaluate the diagnostic quality of attenuation chest X-rays from a dual-contrast scanning prototype.

    Kattau, Margarete / Willer, Konstantin / Noichl, Wolfgang / Urban, Theresa / Frank, Manuela / De Marco, Fabio / Schick, Rafael / Koehler, Thomas / Maack, Hanns-Ingo / Renger, Bernhard / Renz, Martin / Sauter, Andreas / Leonhardt, Yannik / Fingerle, Alexander / Makowski, Marcus / Pfeiffer, Daniela / Pfeiffer, Franz

    European radiology

    2023  Volume 33, Issue 8, Page(s) 5549–5556

    Abstract: Objectives: To compare the visibility of anatomical structures and overall quality of the attenuation images obtained with a dark-field X-ray radiography prototype with those from a commercial radiography system.: Methods: Each of the 65 patients ... ...

    Abstract Objectives: To compare the visibility of anatomical structures and overall quality of the attenuation images obtained with a dark-field X-ray radiography prototype with those from a commercial radiography system.
    Methods: Each of the 65 patients recruited for this study obtained a thorax radiograph at the prototype and a reference radiograph at the commercial system. Five radiologists independently assessed the visibility of anatomical structures, the level of motion artifacts, and the overall image quality of all attenuation images on a five-point scale, with 5 points being the highest rating. The average scores were compared between the two image types. The differences were evaluated using an area under the curve (AUC) based z-test with a significance level of p ≤ 0.05. To assess the variability among the images, the distributions of the average scores per image were compared between the systems.
    Results: The overall image quality was rated high for both devices, 4.2 for the prototype and 4.6 for the commercial system. The rating scores varied only slightly between both image types, especially for structures relevant to lung assessment, where the images from the commercial system were graded slightly higher. The differences were statistically significant for all criteria except for the bronchial structures, the cardiophrenic recess, and the carina.
    Conclusions: The attenuation images acquired with the prototype were assigned a high diagnostic quality despite a lower resolution and the presence of motion artifacts. Thus, the attenuation-based radiographs from the prototype can be used for diagnosis, eliminating the need for an additional conventional radiograph.
    Key points: • Despite a low tube voltage (70 kVp) and comparably long acquisition time, the attenuation images from the dark-field chest radiography system achieved diagnostic quality for lung assessment. • Commercial chest radiographs obtained a mean rating score regarding their diagnostic quality of 4.6 out of 5, and the grating-based images had a slightly lower mean rating score of 4.2 out of 5. • The difference in rating scores for anatomical structures relevant to lung assessment is below 5%.
    MeSH term(s) Humans ; X-Rays ; Radiography, Thoracic/methods ; Radiography ; Thorax ; Lung/diagnostic imaging
    Language English
    Publishing date 2023-02-18
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 1085366-2
    ISSN 1432-1084 ; 0938-7994 ; 1613-3749
    ISSN (online) 1432-1084
    ISSN 0938-7994 ; 1613-3749
    DOI 10.1007/s00330-023-09477-4
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