Spatial resolution characterization of a X-ray microCT system

Rueckel, J.; Stockmar, Marco; Pfeiffer, Franz; Herzen, Julia

doi:10.1016/j.apradiso.2014.08.014

Cited by 82 publications

(40 citation statements)

References 10 publications

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“…Second, we aim to retain the full image resolution and quality during the basis material decomposition process. In microCT imaging, true spatial image resolution is often limited by pixel size, at least for low magnifications (Rueckel et al, 2014). Thus, we focussed on optimizing methods for image filtering and volume image registration.…”

Section: Discussionmentioning

confidence: 99%

Microscopic dual‐energy CT (microDECT): a flexible tool for multichannelex vivo3D imaging of biological specimens

Handschuh

Beisser

Ruthensteiner

et al. 2017

Journal of Microscopy

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Dual-energy computed tomography (DECT) uses two different x-ray energy spectra in order to differentiate between tissues, materials or elements in a single sample or patient. DECT is becoming increasingly popular in clinical imaging and preclinical in vivo imaging of small animal models, but there have been only very few reports on ex vivo DECT of biological samples at microscopic resolutions. The present study has three main aims. First, we explore the potential of microscopic DECT (microDECT) for delivering isotropic multichannel 3D images of fixed biological samples with standard commercial laboratory-based microCT setups at spatial resolutions reaching below 10 μm. Second, we aim for retaining the maximum image resolution and quality during the material decomposition. Third, we want to test the suitability for microDECT imaging of different contrast agents currently used for ex vivo staining of biological samples. To address these aims, we used microCT scans of four different samples stained with x-ray dense contrast agents. MicroDECT scans were acquired with five different commercial microCT scanners from four companies. We present a detailed description of the microDECT workflow, including sample preparation, image acquisition, image processing and postreconstruction material decomposition, which may serve as practical guide for applying microDECT. The MATLAB script (The Mathworks Inc., Natick, MA, USA) used for material decomposition (including a graphical user interface) is provided as a supplement to this paper (https://github.com/microDECT/DECTDec). In general, the presented microDECT workflow yielded satisfactory results for all tested specimens. Original scan resolutions have been mostly retained in the separate material fractions after basis material decomposition. In addition to decomposition of mineralized tissues (inherent sample contrast) and stained soft tissues, we present a case of double labelling of different soft tissues with subsequent material decomposition. We conclude that, in contrast to in vivo DECT examinations, small ex vivo specimens offer some clear advantages regarding technical parameters of the microCT setup and the use of contrast agents. These include a higher flexibility in source peak voltages and x-ray filters, a lower degree of beam hardening due to small sample size, the lack of restriction to nontoxic contrast agents and the lack of a limit in exposure time and radiation dose. We argue that microDECT, because of its flexibility combined with already established contrast agents and the vast number of currently unexploited stains, will in future represent an important technique for various applications in biological research.

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Section: Discussionmentioning

confidence: 99%

Microscopic dual‐energy CT (microDECT): a flexible tool for multichannelex vivo3D imaging of biological specimens

Handschuh

Beisser

Ruthensteiner

et al. 2017

Journal of Microscopy

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“…Thus it is worthwhile to assess the image quality of the CBCT device and other radiographic imaging system quantitatively to ensure the diagnostic accuracy of the chosen modality [28]. Spatial resolution, which is related to the ability of distinguishing two adjacent structures on a radiograph, is one of the parameters, which can be measured objectively allowing us to estimate the imaging performance of an X-ray based medical system [29,30]. There are two main methods for determining the spatial resolution, namely visual resolution assessment test and MTF determination.…”

Section: Introductionmentioning

confidence: 99%

“…Brüllmann et al [29] found in their review, that there is a large variance between the values of observer based visual assessment and the quantitative MTF determination. In addition, numerous studies focusing on MTF measurements as a possible way for quantitatively evaluate the X-ray based imaging devices using cone-beam geometry [28,30,33,[35][36][37]. The image quality and consequently spatial resolution is influenced by several other factors such as focal spot size, overall geometry, tube voltage, tube current, exposure time, rotation arc, the size of field of view (FOV) and the reconstruction parameters as well as the image noise and the movement of the object [7,29,[37][38][39].…”

Section: Introductionmentioning

confidence: 99%

“…The image quality and consequently spatial resolution is influenced by several other factors such as focal spot size, overall geometry, tube voltage, tube current, exposure time, rotation arc, the size of field of view (FOV) and the reconstruction parameters as well as the image noise and the movement of the object [7,29,[37][38][39]. Rueckel et al [30] found in their micro-CT study a significant correlation between the focal spot enlargement, which is strongly influenced by the tube power, and the range of magnification: in the case of magnification higher than 30 the gain of spatial resolution is mainly limited by the focus size and less dominant. In a CBCT study Lee et al [37] concluded that the spatial resolution can be improved by changing the voxel sizes and the reconstruction filters, however the image noise will be increased for smaller voxel sizes.…”

Section: Introductionmentioning

confidence: 99%

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Modulation transfer function evaluation of cone beam computed and microcomputed tomography by using slanted edge phantom

Bence¹

2019

MIPT

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Modulation transfer function (MTF) is a well known and widely accepted method for evaluating the spatial resolution of a digital radiographic imaging system. In the present study our aim was to evaluate the MTF obtained from CBCT and micro-CT images. A cylinder shaped phantom designed for slanted-edge method was scanned by a CBCT device at a 100 µm isometric voxel size and by a micro-CT device at a 20 µm isometric voxel size, simultaneously. The MTF curves were calculated and the mean spatial resolutions at 10% MTF were 3.33 + 0.29 lp/mm in the case of CBCT images and 13.35 + 2.47 lp/mm in the case of micro-CT images. The values showed a strong positive correlation regarding the CBCT and the micro-CT spatial resolution values, respectively. Our results suggests that CBCT imaging devices with a voxel size of 100 µm or below might aid the validation of fine anatomical structures and allowing the opportunity for reliable micromorphometric examinations

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“…On the other hand, sufficient radiation intensities are necessary to achieve adequate signal-to-noise ratios. These two image quality criteria, which are contrarily related to the tube power, need to be well balanced in a sample specific way" [123].…”

Section: Introductionmentioning

confidence: 99%

Foxels for high flux, high resolution computed tomography (foxelct) Using broad x-ray focal spots

Alvare¹,

Gordon²

2017

Radiol Diagn Imaging

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Purpose: In general, there is a reciprocal relationship between the width and flux from an x-ray focal spot (corresponding to spatial resolution and photon noise), so that large focal spots are eschewed in computed tomography (CT) and projection and CT mammography. We wish to overcome this limitation. The goal of foxel based computed tomography (FoxelCT) is to achieve spatial resolution limited by the detector pixel size rather than the focal spot size, and therefore permit the use of much smaller detector pixels and/or larger focal spots in clinical CT. Methods:Rather than using the standard approach of treating the x-ray source as a point, we digitally represent the focal spot as an emission picture consisting of pixels we call foxels (FOcal spot piXELS). Intersections of foxel rays with reconstruction voxels are approximated using the Wu antialiasing line drawing algorithm. All foxel rays in the x-ray light field impinging on a given detector pixel are, in effect, lumped together into a single "passage" or compound ray sum. In this introductory paper noise and other effects that degrade CT are not considered allowing us to demonstrate the upper bound of improvement afforded by the geometry of foxels. The FoxelCT algorithm is a generalization of MART (Multiplicative ART). Results:We show, by simulating a fan beam body scanner configuration, that the loss in resolution versus focal spot size is much slower using foxels compared to the loss when representing the focal spot as a point source. For any given focal spot size, approximating it as a point is always worse than using foxels and furthermore introduces anatomical distortions.Conclusions: Foxels permit the use of larger focal spots and thus greater x-ray photon flux with little loss of resolution. Future scanners could take advantage of foxels to increase the ratio of focal spot size to detector pixel size, via bigger focal spots and/or smaller detector pixels. Existing scanners could be immediately enhanced in image quality via incorporation of foxels in their software. Foxels are applicable to any form of radiological imaging that uses focal spots of finite width, including multisource scanners.

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Spatial resolution characterization of a X-ray microCT system

Cited by 82 publications

References 10 publications

Microscopic dual‐energy CT (microDECT): a flexible tool for multichannelex vivo3D imaging of biological specimens

Microscopic dual‐energy CT (microDECT): a flexible tool for multichannelex vivo3D imaging of biological specimens

Modulation transfer function evaluation of cone beam computed and microcomputed tomography by using slanted edge phantom

Foxels for high flux, high resolution computed tomography (foxelct) Using broad x-ray focal spots

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