Tracking based, high-resolution single-shot multimodal x-ray imaging in the laboratory enabled by the sub-pixel resolution capabilities of the MÖNCH detector
Abstract:The simultaneous retrieval of X-ray attenuation, phase, and scattering using multimodal imaging techniques is finding increased use in a range of applications, from medicine to materials science. Most techniques rely on the mechanical movement of an optical element (e.g. a grating or a mask) to obtain the multi-modal images. While single-shot approaches exist, they typically employ detector pixels smaller than the grating period, often with low detection efficiency, and are limited in resolution unless either … Show more
“…Furthermore, they show less artefacts due to smearing or blurring within the scintillator. Another novel research branch in the detector improvement is dedicated to the development of 2d energy resolving detectors (similar to Silicon Drift Detectors) such as a hybrid silicon pixel detector based on charge integration and analog readout [113][114][115].…”
Section: Developments In X-ray Detectionmentioning
List of publications
Danksagung
Curriculum Vitaeday. Considering an average volume of 70 ml to 80 ml per beat, more than 7 000 liters of blood are pumped through the body each day. The synchronized contraction of the excitable cardiac tissue cells is controlled by the conduction system, which initiates an electric signal in the sinoatrial node and coordinates the propagation of the action potential through the heart. The continuous function of the heart during its entire lifetime is essential for the proper maintenance of all vital organs. Small dysfunctions or abnormalities can cause drastic changes and effects in the human organism. Therefore, it is very important to understand the cardiac structure from the molecular level up to the scale of the entire organ, as well as its function within the body.The primary aim of this thesis is to develop imaging protocols to probe the entire cy-
Cardiac structure and (dys)functionCardiovascular diseases (CVDs) are the main cause of death worldwide with a rising incidence. While CVDs were responsible for less than 10% of the deaths worldwide by the beginning of the 20th century, the number of CVD-related deaths increased to over 30% by 2016 [6-8]. This corresponds to 17.9 million global deaths due to CVDs in one year. The major share of these death (85%) is attributed to heart attacks and from the ancient Egyptians [17]. (B) Drawing of the cardiac anatomy by Aristotle [15]. (C) Sketch of the heart by Leonardo da Vinci [15]. (D) Cardiac model by Richard Lower [18]. (E) Text book figure of Henry Gray's anatomy [16]. (F) Concept of a "Triebwerk" by Ludolf Krehl [18]. (G) Jane Sands Robb's model of the heart [18]. (H) Cardiac fiber model of Alfred Benninghoff and Kurt Goerttler [18]. (I) Model of the helical ventricular band by Francisco Torrent-Guasp [18]. Anatomie des Menschen"), Xavier Bichat ("Anatomie Generale") and Henry Gray and Henry Vandyke Carter ("Grays Anatomy"). Nevertheless, due to ongoing research and new discoveries the textbooks had to be updated constantly. In October 2020, the 42th edition of "Grays Anatomy" was released. Concerning the cardiac anatomy, most of the open questions were related to the cardiac function and structural changes caused by CVDs. For example, in 1891 Ludolf Krehl introduced the idea of a circumferential Historically, the observation of the heart structure started by documenting visual impressions gained from evisceration of animals or autopsies. With progress in the manufacture of optics and the invention of the microscope in the 17th century, it was possible to investigate structures in the micrometer range [48]. During this time, Marcello Malpighi was the first who identified small capillaries in the lungs of bats and established the process of oxygen uptake [49]. This procedure, later called histology (from Greek: histos, tissue and logos, study), revealed its full potential during the 19th Recently, this invention was further developed by a combination of STED and single molecule localization microscopy such as stochastic optical...
“…Furthermore, they show less artefacts due to smearing or blurring within the scintillator. Another novel research branch in the detector improvement is dedicated to the development of 2d energy resolving detectors (similar to Silicon Drift Detectors) such as a hybrid silicon pixel detector based on charge integration and analog readout [113][114][115].…”
Section: Developments In X-ray Detectionmentioning
List of publications
Danksagung
Curriculum Vitaeday. Considering an average volume of 70 ml to 80 ml per beat, more than 7 000 liters of blood are pumped through the body each day. The synchronized contraction of the excitable cardiac tissue cells is controlled by the conduction system, which initiates an electric signal in the sinoatrial node and coordinates the propagation of the action potential through the heart. The continuous function of the heart during its entire lifetime is essential for the proper maintenance of all vital organs. Small dysfunctions or abnormalities can cause drastic changes and effects in the human organism. Therefore, it is very important to understand the cardiac structure from the molecular level up to the scale of the entire organ, as well as its function within the body.The primary aim of this thesis is to develop imaging protocols to probe the entire cy-
Cardiac structure and (dys)functionCardiovascular diseases (CVDs) are the main cause of death worldwide with a rising incidence. While CVDs were responsible for less than 10% of the deaths worldwide by the beginning of the 20th century, the number of CVD-related deaths increased to over 30% by 2016 [6-8]. This corresponds to 17.9 million global deaths due to CVDs in one year. The major share of these death (85%) is attributed to heart attacks and from the ancient Egyptians [17]. (B) Drawing of the cardiac anatomy by Aristotle [15]. (C) Sketch of the heart by Leonardo da Vinci [15]. (D) Cardiac model by Richard Lower [18]. (E) Text book figure of Henry Gray's anatomy [16]. (F) Concept of a "Triebwerk" by Ludolf Krehl [18]. (G) Jane Sands Robb's model of the heart [18]. (H) Cardiac fiber model of Alfred Benninghoff and Kurt Goerttler [18]. (I) Model of the helical ventricular band by Francisco Torrent-Guasp [18]. Anatomie des Menschen"), Xavier Bichat ("Anatomie Generale") and Henry Gray and Henry Vandyke Carter ("Grays Anatomy"). Nevertheless, due to ongoing research and new discoveries the textbooks had to be updated constantly. In October 2020, the 42th edition of "Grays Anatomy" was released. Concerning the cardiac anatomy, most of the open questions were related to the cardiac function and structural changes caused by CVDs. For example, in 1891 Ludolf Krehl introduced the idea of a circumferential Historically, the observation of the heart structure started by documenting visual impressions gained from evisceration of animals or autopsies. With progress in the manufacture of optics and the invention of the microscope in the 17th century, it was possible to investigate structures in the micrometer range [48]. During this time, Marcello Malpighi was the first who identified small capillaries in the lungs of bats and established the process of oxygen uptake [49]. This procedure, later called histology (from Greek: histos, tissue and logos, study), revealed its full potential during the 19th Recently, this invention was further developed by a combination of STED and single molecule localization microscopy such as stochastic optical...
“…We reiterate that this straightforward improvement to spatial resolution achievable by the GPM when using direct detectors is a consequence of the single-pixel PSFs they possess and hence would equivalently improve data recorded with indirect detectors of similar PSF. Similarly, methods allowing sub-pixel resolution through localisation of charge clouds caused by X-ray interaction with the detector, performed with indirect 25 – 27 and direct detectors 28 , 29 , would likely benefit further from the GPM rederivation. Figure 4 PSFs measured by azimuthally averaging the outer edge PMMA cylinders in CT recorded at 2 m propagation distance with beam energy using ( a ) a Advacam Modupix and ( b ) a LAMBDA photon-counting detector.…”
The ill-posed problem of phase retrieval in optics, using one or more intensity measurements, has a multitude of applications using electromagnetic or matter waves. Many phase retrieval algorithms are computed on pixel arrays using discrete Fourier transforms due to their high computational efficiency. However, the mathematics underpinning these algorithms is typically formulated using continuous mathematics, which can result in a loss of spatial resolution in the reconstructed images. Herein we investigate how phase retrieval algorithms for propagation-based phase-contrast X-ray imaging can be rederived using discrete mathematics and result in more precise retrieval for single- and multi-material objects and for spectral image decomposition. We validate this theory through experimental measurements of spatial resolution using computed tomography (CT) reconstructions of plastic phantoms and biological tissues, using detectors with a range of imaging system point spread functions (PSFs). We demonstrate that if the PSF substantially suppresses high spatial frequencies, the potential improvement from utilising the discrete derivation is limited. However, with detectors characterised by a single pixel PSF (e.g. direct, photon-counting X-ray detectors), a significant improvement in spatial resolution can be obtained, demonstrated here at up to 17%.
“…More recently, methods have emerged that allow retrieving three-modal x-ray images from a single frame 16 – 25 . In these, the analyzer is replaced by a high-resolution detector, featuring pixels small enough to resolve the reference pattern created by the modulator, and therefore allowing to extract the changes caused by the sample’s attenuation, refraction, and scattering without acquiring and processing multiple frames.…”
Section: Introductionmentioning
confidence: 99%
“…In this scenario, the sample’s attenuation, refraction, and scattering lead to an intensity reduction, shift, and broadening of the beamlets, respectively. If a mask with long, narrow slits is used 22 , 23 , beam tracking is sensitive to phase effects (refraction, scattering) in the direction orthogonal to the slits, while two-dimensional phase sensitivity is achieved with a mask with square or round apertures (“holes”) 24 , 25 .…”
We present a flyscan compatible acquisition scheme for three-modal X-Ray Computed Tomography (CT) with two-dimensional phase sensitivity. Our approach is demonstrated using a “beam tracking” setup, through which a sample’s attenuation, phase (refraction) and scattering properties can be measured from a single frame, providing three complementary contrast channels. Up to now, such setups required the sample to be stepped at each rotation angle to sample signals at an adequate rate, to prevent resolution losses, anisotropic resolution, and under-sampling artefacts. However, the need for stepping necessitated a step-and-shoot implementation, which is affected by motors’ overheads and increases the total scan time. By contrast, our proposed scheme, by which continuous horizontal and vertical translations of the sample are integrated with its rotation (leading to a “cycloidal-spiral” trajectory), is fully compatible with continuous scanning (flyscans). This leads to greatly reduced scan times while largely preserving image quality and isotropic resolution.
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