A5019247249- Medical Imaging Techniques and Applications
- Advanced X-ray and CT Imaging
- Radiation Dose and Imaging
- Advanced MRI Techniques and Applications
- Advanced Radiotherapy Techniques
- Cardiac Imaging and Diagnostics
- Radiomics and Machine Learning in Medical Imaging
- Digital Radiography and Breast Imaging
- Medical Image Segmentation Techniques
- Image and Signal Denoising Methods
- Advanced X-ray Imaging Techniques
- Radiation Therapy and Dosimetry
- Electrical and Bioimpedance Tomography
- Dental Radiography and Imaging
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Welding Techniques and Residual Stresses
- MRI in cancer diagnosis
- Non-Invasive Vital Sign Monitoring
- Nuclear Physics and Applications
- Medical Imaging and Analysis
- Ultrasound and Hyperthermia Applications
- Prostate Cancer Treatment and Research
- Radiopharmaceutical Chemistry and Applications
- Microwave Imaging and Scattering Analysis
German Cancer Research Center
2016-2025
Heidelberg University
2016-2025
University Hospital Heidelberg
2017-2025
DKFZ-ZMBH Alliance
2014-2024
Siemens Healthcare (Germany)
2012-2019
Institute of Cancer Research
2017
Christian Medical College & Hospital
2016
Cardiff University
2016
Friedrich-Alexander-Universität Erlangen-Nürnberg
2005-2014
Heidelberg University
2013
Purpose: While modern clinical CT scanners under normal circumstances produce high quality images, severe artifacts degrade the image and diagnostic value if metal prostheses or other objects are present in field of measurement. Standard methods for artifact reduction (MAR) replace those parts projection data that affected by (the so‐called trace shadow) interpolation. However, while sinogram interpolation efficiently remove artifacts, new often introduced, as cannot completely recover...
We investigated the applicability and image quality of contrast-enhanced coronary artery visualization by multislice spiral CT using retrospective ECG gating.Twenty-five patients in sinus rhythm (significant stenoses ruled out invasive angiography) were studied with a (Siemens SOMATOM Volume Zoom). In inspiration (mean breath-hold, 37 seconds), volume data set heart was acquired (intravenous contrast agent; 4 x 1-mm slice thickness; 500-ms rotation; table feed, 1.5 mm/360 degrees )....
In computed tomography there are different situations where reconstruction has to be performed with limited raw data. the past few years it been shown that algorithms which based on compressed sensing theory able handle incomplete datasets quite well. As a cost function these use ℓ1-norm of image after transformed by sparsifying transformation. This yields an inequality-constrained convex optimization problem. Due large size problem some heuristic have proposed in years. The most popular way...
The problem of metal artifact reduction (MAR) is almost as old the clinical use computed tomography itself. When implants are present in field measurement, severe artifacts degrade image quality and diagnostic value CT images. Up to now, no generally accepted solution this issue has been found. In work, a method based on new MAR concept presented: frequency split (FSMAR). It ensures efficient at high with enhanced preservation details close implants.FSMAR combines raw data inpainting-based...
To study the performance of different dual energy computed tomography (DECT) techniques, which are available today, and future multi CT (MECT) employing novel photon counting detectors in an image-based material decomposition task.The energy-resolved acquisition techniques is assessed compared a simulation virtual non-contrast imaging iodine quantification. The material-specific images obtained via statistically optimal decomposition. A projection-based maximum likelihood approach was used...
In modern computed tomography (CT) there is a strong desire to reduce patient dose and/or improve image quality by increasing spatial resolution and decreasing noise. These are conflicting demands since at constant noise level or implies higher demand on x‐ray power an increase of dose. X‐ray tube limited due technical reasons. We therefore developed generalized multi‐dimensional adaptive filtering approach that applies nonlinear filters in up three dimensions the raw data domain. This new...
Subsecond spiral computed tomography (CT) offers great potential for improving heart imaging. The new multi‐row detector technology adds significantly to this potential. We therefore developed and validated dedicated cardiac reconstruction algorithms imaging the with subsecond multi‐slice CT utilizing electrocardiogram (ECG) information. single‐slice z ‐interpolation 180°CI 180°CD [Med. Phys. 25 , 2417–2431 (1998)] were generalized allow of M ‐slice scanners. Two classes investigated:...
Subsecond computed tomography (CT) scanning offers potential for improved heart imaging. We therefore developed and validated dedicated reconstruction algorithms imaging the with subsecond spiral CT utilizing electrocardiogram (ECG) information. modified z ‐interpolation on a scanner. Two new classes of were investigated: (a) 180°CI (cardio interpolation), piecewise linear interpolation between adjacent data segments belonging to same phase where are selected by correlation simultaneously...
Dual energy CT (DECT) measures the object of interest using two different x-ray spectra in order to provide energy-selective images or get material decomposition object. Today, techniques are known. Image-based DECT uses linear combinations reconstructed an image that contains material-selective information. Rawdata-based correctly treats available information by passing rawdata through a function from both sets create specific (e.g., material-selective) rawdata. Then reconstruction yields...
Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend be underestimated. Cupping hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these can reduced by precorrecting rawdata. Higher order artifacts, they result when a mixture of materials water bone, or bone iodine require an iterative correction where image segmented into different those are forward projected obtain new...
Purpose: Dual Energy CT (DECT) provides so‐called monoenergetic images based on a linear combination of the original polychromatic images. At certain patient‐specific energy levels, corresponding to patient‐ and slice‐dependent weights, e.g., E = 160 keV corresponds α 1.57, significant reduction metal artifacts may be observed. The authors aimed at analyzing method for its artifact capabilities identify limitations. results are compared with raw data‐based processing. Methods: Clinical DECT...
X-ray scatter is a major cause of image quality degradation in dimensional CT. Especially, case highly attenuating components scatter-to-primary ratios may easily be higher than 1. The corresponding artifacts which appear as cupping or dark streaks the CT reconstruction impair metrological assessment. Therefore, an appropriate correction crucial. Thereby, gold standard to predict distribution using Monte Carlo (MC) code and subtract estimate from measured raw data. MC, however, too slow used...
Purpose X‐ray scattering leads to CT images with a reduced contrast, inaccurate values as well streak and cupping artifacts. Therefore, scatter correction is crucial maintain the diagnostic value of CBCT examinations. However, existing approaches are not able combine both high accuracy computational performance. we propose deep estimation (DSE): convolutional neural network derive highly accurate estimates in real time. Methods Gold standard rely on dedicated Monte Carlo (MC) photon...
Objectives Reconstructing images from measurements with small pixels below the system's resolution limit theoretically results in image noise reduction compared larger pixels. We evaluate and quantify this effect using data acquired of a photon-counting (PC) computed tomography scanner that can be operated different detector pixel binning modes conventional energy-integrating (EI) detector. Materials Methods An anthropomorphic abdominal phantom extended to 3 sizes by adding fat extension...
Computed tomography (CT) dramatically improved the capabilities of diagnostic and interventional radiology. Starting in early 1970s, this imaging modality is still evolving, although tremendous improvements scan speed, volume coverage, spatial soft tissue resolution, as well dose reduction have been achieved. Tube current modulation, automated exposure control, anatomy-based tube voltage (kV) selection, advanced x-ray beam filtration, iterative image reconstruction techniques quality...
To achieve higher volume coverage at improved z ‐resolution in computed tomography (CT), systems with a large number of detector rows are demanded. However, handling an increased rows, as compared to today's four‐slice scanners, requires accounting for the cone geometry beams. Many so‐called cone‐beam reconstruction algorithms have been proposed during last decade. None met all requirements medical spiral CT regard need high image quality, low patient dose and times. We therefore propose...
We present a new high‐precision method for the geometric calibration in cone‐beam computed tomography. It is based on Fourier analysis of projection‐orbit data, recorded with flat‐panel area detector, individual point‐like objects. For circular scan trajectories complete set misalignment parameters which determine deviation detector alignment from ideal geometry are obtained explicit analytic expressions. To derive these expressions we show how to disentangle problems calculating and point...
We propose an empirical cupping correction (ECC) algorithm to correct for CT artifacts that are induced by nonlinearities in the projection data. The method is raw data based, empirical, and requires neither knowledge of x‐ray spectrum nor attenuation coefficients. It aims at linearizing using a precorrection function polynomial form. coefficients determined once calibration scan homogeneous phantom. Computing done image domain fitting series basis images template image. obtained directly...
Material‐selective imaging using dual energy CT (DECT) relies heavily on well‐calibrated material decomposition functions. These require the precise knowledge of detected x‐ray spectra, and even if they are exactly known reliability DECT will suffer from scattered radiation. We propose an empirical method to determine proper function. In contrast other algorithms our calibration (EDEC) technique requires neither spectra nor attenuation coefficients. The desired material‐selective raw data...