User profiles for Christian Wülker

Christian Wülker

Research Scientist, Philips Research Hamburg
Verified email at philips.com
Cited by 47

Time-of-flight PET image reconstruction using origin ensembles

C Wülker, A Sitek, S Prevrhal - Physics in Medicine & Biology, 2015 - iopscience.iop.org
The origin ensemble (OE) algorithm is a novel statistical method for minimum-mean-square-error
(MMSE) reconstruction of emission tomography data. This method allows one to …

[HTML][HTML] Quantizing Euclidean motions via double-coset decomposition

C Wülker, S Ruan, GS Chirikjian - Research, 2019 - spj.science.org
Abstract Concepts from mathematical crystallography and group theory are used here to
quantize the group of rigid-body motions, resulting in a “motion alphabet” with which robot …

Digital reference objects for evaluating algorithm performance in MR image formation

C Wülker, NT Gessert, M Doneva, S Kastryulin… - Magnetic Resonance …, 2024 - Elsevier
Purpose Digital Reference Objects (DROs) are mathematical phantoms that can serve as a
basis for evaluating MR image quality (IQ) in an objective way. Their main purpose is to …

Fast Fourier transforms for spherical Gauss-Laguerre basis functions

J Prestin, C Wülker - Frames and Other Bases in Abstract and Function …, 2017 - Springer
Spherical Gauss-Laguerre (SGL) basis functions, ie, normalized functions of the type L n−l−1
(l+1∕2)​ (r 2 )r l Y lm (ϑ, φ), | m | ≤ l < n ∈ ℕ $$\vert m\vert \leq l < n \in \mathbb{N}$$ , L n…

Estimation of incomplete organ-coverage using 3D fully convolutional networks

…, S Gotman, T Buelow, C Wülker - Medical Imaging …, 2023 - spiedigitallibrary.org
Deviations from the MR acquisition guidelines could lead to images with serious quality
concerns such as incompletely imaged anatomies, which might require re-examinations and …

Estimation of the ankle-joint space visibility in x-ray images using convolutional neural networks

…, JM May, B Lundt, M Brück, C Wülker - Medical Imaging 2023 …, 2023 - spiedigitallibrary.org
For the X-ray image acquisition one of the most important factors for diagnostic quality is the
patient position with respect to the X-ray tube and the detector. In case of orthopedic lateral …

Quotienting impertinent camera kinematics for 3D video stabilization

TW Mitchel, C Wulker, J Seob Kim… - Proceedings of the …, 2019 - openaccess.thecvf.com
With the recent advent of methods that allow for real-time computation, dense 3D flows have
become a viable basis for fast camera motion estimation. Most importantly, dense flows are …

Improved coronary artery calcium (CAC) detection in conventional CT with deep-learning image de-blurring

C Wülker, NR van der Werf… - … 2024: Physics of …, 2024 - spiedigitallibrary.org
We investigated the impact of a CNN-based deep-learning (DL) image de-blurring algorithm
on coronary artery calcium (CAC) detection performance in conventional CT imaging. Our …

Fast Fourier Transforms for Spherical Gauss-Laguerre Basis Functions

J Prestin, C Wülker - arXiv preprint arXiv:1604.05140, 2016 - arxiv.org
Spherical Gauss-Laguerre (SGL) basis functions, ie, normalized functions of the type $L_{nl-1}^{(l
+ 1/2)} (r^2) r^{l} Y_{lm}(\vartheta,\varphi)$, $|m| \leq l < n \in \mathbb{N}$, $L_{nl-1}^{(l …

Fat-constrained 18F-FDG PET reconstruction in hybrid PET/MR imaging

S Prevrhal, S Heinzer, C Wülker… - Journal of Nuclear …, 2014 - Soc Nuclear Med
Fusion of information from PET and MR imaging can increase the diagnostic value of both
modalities. This work sought to improve 18 F FDG PET image quality by using MR Dixon fat-…