Journal of X-Ray Science and Technology - Volume 18, issue 2

Authors: Ji, Changguo

Article Type: Research Article

Abstract: Purpose: In circular cone-beam microcomputed tomography (micro-CT), it is likely that the length of the Field of View (FOV) of a single acquisition is shorter than the total length of the object to be imaged, such as a rat in the case of preclinical application of micro-CT. This leads to multiple acquisitions using different bed positions with bed translations in between, which can be automated using a motorized bed stage. However, subtle mechanical inaccuracies can cause …undesired effects when the reconstructed volumes of the different acquisitions are combined into one larger volume. In this paper, we develop an automated method for accurately stitching 3D computed tomography (CT) data using an image registration scheme, and validate this technique in a circular cone-beam micro-CT scanner. Methods: The approach is based on precalculated spatial transformation matrices acquired by a calibration phantom with point markers at stitching positions. The spatial transformation between two adjacent subvolumes was calculated only once with a rigid-body matching algorithm. Once all transformation matrices are obtained, all subsequent reconstructed subvolumes imaged at these fixed positions can be stitched accurately, and efficiently using these precalculated matrices. Results: We applied this method to real object/animal imaging in circular cone-beam micro-CT and compared the result with that obtained by stitching method calculated only by translation distances and CT voxel size. Both stitching errors calculated using point markers and stitched volumes of rigid object (a syringe) and small animal (a rat) illustrated the success of our proposed approach. Conclusions: Preliminary experimental results demonstrate that "3D data stitching" using an image registration scheme provides a good solution to the voxel mismatch caused by limited FOV length in circular cone-beam micro-CT. This method can be extended to other tomography techniques which need to acquire data at fixed scanning positions. Show more

DOI: 10.3233/XST-2010-0246

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 99-110, 2010

Authors: Durak, R. | Gülen, Y. | Kurudirek, M. | Kaçal, M. | Çapoğlu, İ.

Article Type: Research Article

Abstract: The present study investigated the trace element contents in the blood sera of type II diabetic patients with and without complication as compared to non-diabetic healthy controls. The elements Na, Mg, Al, Si, P, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se, Mo, Cd, Hg and Pb were determined by wavelength dispersive x-ray fluorescence spectrometry. Blood serum levels of some trace elements in patients with type II diabetes mellitus showed significant deviations …from healthy controls. Mean Ca, Cu and Se (p< 0.05) concentrations (%) in both diabetic patients with and without complication were significantly lower than those in healthy controls. When compared with non-diabetic control group, the Mg concentrations of patients without complication were decreasing while Mg levels of patients with at least one complication were increasing (p< 0.05). Si levels were significantly higher both in diabetic patients with complication and without complication than healthy controls (p< 0.05). K and Hg levels of diabetic patients with at least one complication have significantly deviated from both healthy controls and patients without complication (p< 0.05). There were no significant differences between control group and diabetic patients concerning height, age, weight and body mass index (p> 0.05). Show more

Keywords: Diabetes mellitus, trace elements, blood serum, wavelength dispersive x-ray fluorescence spectrometry

DOI: 10.3233/XST-2010-0247

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 111-120, 2010

Authors: Celenk, Mehmet | Farrell, Mike L. | Eren, Haluk | Kumar, K. | Singh, G. Dave | Lozanoff, Scott

Article Type: Research Article

Abstract: This paper describes a method developed to assist in the detection and reconstruction of a three dimensional (3D) model of the human upper airway using cone beam computed tomography (CBCT) image slices and a 3D Gaussian smoothing kernel. The segmented and reconstructed volumetric airway is characterized by the corresponding three principal axes that are selected for viewing direction orientation via rotation and translation. These axes are derived using the 3D Principal Component Analysis (PCA) result of …the rendered volume. To finely adjust the view and access airway, the major and minor axes of each slice are also computed using the two dimensional (2D) PCA in the respective planes. The exterior volume view is visualized in two modes, namely, a solid surface (volume details transparent to user) view and a nontransparent (volume detail accessible) view. This functionality provides an application driven use of the 3D airway in CBCT based anatomy studies. The extracted information may be useful as an imaging biomarker in the diagnostic assessment of patients with upper airway respiratory conditions such as obstructive sleep apnea, allergic rhinitis, and other related diseases; as well as planning orthopedic/orthodontic therapies. Show more

Keywords: CBCT images, upper airway image slices, Gaussian kernel blurring filter, upper airway segmentation, PCA, volumetric upper airway visualization

DOI: 10.3233/XST-2010-0248

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 121-135, 2010

Authors: Papp, Laszlo | Juhasz, Reka | Travar, Sonja | Kolli, Alexander | Sorantin, Erich

Article Type: Research Article

Abstract: Funnel chest (Pectus excavatum) is the most common deformity of the anterior chest in children. Present paper describes a method to process and classify CT slices representing funnel chest deformities. A manually chosen CT slice was processed to detect the inner curvature of the chest for characterization. Normalized data from the detected inner curvature was gained and saved next to a manually-given deformity type for further classification rule determinations. Based on the multiple correlations of the …values gained from the inner curvature, a hierarchical classification was performed on 199 patient data. Results have shown that the calculated values gained from the inner curvature can accurately characterize the deformity type of the chest. Since minimal user interaction was necessary to detect and characterize the inner curvature, our method is considered to be an effective automated procedure for funnel chest deformity classifications. Show more

DOI: 10.3233/XST-2010-0249

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 137-144, 2010

Authors: Fang, Sheng | Ying, Kui | Cheng, Jianping | Wang, Shi | Zhang, Jing | Xiao, Zhikui | Shen, Hao

Article Type: Research Article

Abstract: The parallel imaging technique reduces the scan time at the expense of increased noise, due to its ill-conditioned system matrix. Tikhonov regularization has been proposed for SENSE to reduce the noise. However, Tikhonov regularized images suffer from residual aliasing aritfacts or image blurring when a low resolution prior image is used. This study used wavelet-based multivariate regularization to overcome this problem, while maintaining the computational efficiency of Tikhonov regularization. In this method, …SENSE is formularized as a multilevel-structured problem in the wavelet domain. Regularization is adaptively performed based on the noise behavior for different levels and orientations throughout the wavelet domain. Both Tikhonov regularization and the present method are systematically evaluated using in vivo anatomical brain data and diffusion weighted brain data. Qualitative and quantitative results demonstrate the advantage of multivariate regularization over Tikhonov regularization in the presence of low resolution prior images. This method suits most parallel imaging applications, especially when a high-quality prior image is unavailable, such as diffusion weighed imaging. Show more

Keywords: Regularization, wavelet, multivariate, SENSE, Tikhonov, parallel imaging

DOI: 10.3233/XST-2010-0250

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 145-155, 2010

Authors: Yang, Yong | Park, Dong Sun | Huang, Shuying | Yang, Jucheng

Article Type: Research Article

Abstract: The fusion of multimodal medical images plays an important role in many clinical applications as it can support more accurate information than any individual source image. This paper presents a novel approach for fusion of computed tomography (CT) and magnetic resonance (MR) images based on wavelet transform. The medical images to be fused are firstly decomposed into multiscale representations by the wavelet transform. Then, by considering the physical meaning of wavelet coefficients and the characteristics of …the CT and MR images, the coefficients of the low frequency band and high frequency bands are treated with different schemes: the former is performed with a maximum-selection (MS) rule, and the latter is convolved with a Laplacian operator followed by a MS rule. Finally, the fused image is reconstructed by using the inverse wavelet transform with the combined wavelet coefficients. The performance of our method is qualitatively and quantitatively compared with some existing fusion approaches. The experimental results can demonstrate that the proposed method is a promising and effective technique for fusion of CT and MR images. Show more

Keywords: Multimodal medical images, image fusion, wavelet transform, coefficients

DOI: 10.3233/XST-2010-0243

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 157-170, 2010

Authors: Zhao, Zhanqi | Steinmann, Daniel | Müller-Zivkovic, Danijela | Martin, Jörg | Frerichs, Inéz | Guttmann, Josef | Möller, Knut

Article Type: Research Article

Abstract: Purpose: To evaluate a novel method for lung area estimation (LAE method) in electrical impedance tomography (EIT) images as a prerequisite of quantitative analysis of ventilation inhomogeneity. Methods: The LAE method mirrors the lung regions in the functional EIT (fEIT) image and subsequently subtracts the cardiac related areas. In this preliminary study, 51 mechanically ventilated patients were investigated, including 39~patients scheduled for thoracic surgery (test group); 10~patients scheduled for orthopedic …surgery without pulmonary disease (control group) and 2 ICU patients undergoing chest computed tomography (CT) examination. EIT data was recorded in all groups. The results of the LAE method were compared to those obtained with the fEIT method and to CT images. Results: The lung area size determined with fEIT in control group is S_{C,fEIT} =361 ± 35 (mean ± SD) and in test group S_{T,fEIT} = 299 ± 61 (p< 0.01). The sizes estimated with the LAE method in control group S_{C,LAE} = 353 ± 27 and in test group S_{T,LAE} = 353 ± 61 (p=0.41). The result demonstrates that the novel LAE method improves the identification of lung region in EIT images, from which the analysis of ventilation distribution will benefit. The preliminary comparison with CT images exemplarily indicates a closer match of the lung area shapes after the LAE than after the fEIT-based analysis. Conclusion: The LAE method is a robust lung area determination method, suitable for patients with healthy or seriously injured lungs. Show more

Keywords: Functional electrical impedance tomography, lung area determination, cardiac related area, regional lung function

DOI: 10.3233/XST-2010-0252

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 171-182, 2010

Authors: Kurudirek, Murat | Özdemir, Yüksel

Article Type: Research Article

Abstract: The total photoelectric cross sections, σ_{pe} , of some compounds have been determined from the measured total attenuation cross sections by subtracting the scattering contributions at 59.54 keV. The values of σ _{pe} were then used to compute effective atomic numbers, Z_{eff} for photoelectric process at 59.54 keV. Different methods such as a direct method, an interpolation procedure and an empirical relation were employed to calculate effective atomic numbers …for different compounds wherever possible. Merits and demerits of the used methods were also discussed. The obtained values of σ _{pe} and Z_{eff} from the measurements were compared with the calculated ones from theory. Show more

Keywords: Photoelectric cross section, effective atomic number, effective electron density

DOI: 10.3233/XST-2010-0253

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 183-191, 2010

Authors: Özdemir, Yüksel | Bayındır, Yusuf Ziya | Durna, Doğan | Durak, Rıdvan

Article Type: Research Article

Abstract: This work relates to the measurement of calcium, potassium, manganese and sodium levels in adult-human teeth from female and male patients and normal subjects. Energy dispersive X-ray fluorescence (EDXRF) technique was used for the measurements. Pathological and non-pathological adult-human teeth samples were collected from one male human patient and one female human patient who attended the dental clinic. The standard addition method was used to determine concentrations. Experimental results are presented and discussed in …this work. Show more

Keywords: X-ray fluorescence, trace elements analyzed, XRF analysis of biological samples

DOI: 10.3233/XST-2010-0254

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 193-199, 2010

Authors: Bourbia, A. | Draissia, M. | Bedboudi, H. | Boulkhessaim, S. | Debili, M.Y.

Article Type: Research Article

Abstract: This article deals with the microstructural strengthening mechanisms of aluminium by means of hard α-Al_{2} O_{3} alumina fine particles. A broad of understanding views covering materials preparations, elaboration process, characterization techniques and associated microstructural characteristic parameters measurements is given. In order to investigate the microstructural characteristic parameters and the mechanical strengthening mechanisms of pure aluminium by hard fine particles, a set of Al-(α-Al_{2} O_{3} ) …alloys samples were made under vacuum by high fusion temperature melting, the high frequency (HF) process, and rapidly solidified under ambient temperature from a mixture of cold-compacted high-pure fine Al and α-Al_{2} O_{3} powders. The as-solidified Al-(α-Al_<FORMULA>_{2} O_{3} ) alloys were characterized by means of X-ray diffraction (XRD) analyses, optical microscopy observations and Vickers microhardness tests in both brut and heat-treated states. It was found that the as-solidified HF Al-(α-Al_{2} O_{3} ) alloys with compositions below 4 wt.% (α-Al_{2}<FORMULA>_O<FORMULA>_{3} ) are single-phase microstructures of the solid solution FCC Al phase and over two-phase microstructures of the solid solution FCC Al and the Rhombohedral α-Al_{2} O_{3} phases. The optical micrographs reveal the presence of a grain size refinement in these alloys. Vickers microhardness of the as-solidified Al-(α-Al_{2} O_{3} ) is increased by means of pure fine α-Al_{2} O_{3} alumina particles. These combined effects of strengthening and grain size refinement observed in the as-solidified Al-(α-Al_{2} O_{3} ) alloys are essentially due to a strengthening of Al by the α-Al_{2} O_{3} alumina particles insertion in the (HF) melted and rapidly solidified alloys. Show more

Keywords: HF fusion, Aluminium alloys, α-Al_{2}O_{3} alumina fine particles, Microstructure characteristic parameters, Strengthening mechanisms

DOI: 10.3233/XST-2010-0245

Citation: Journal of X-Ray Science and Technology, vol. 18, no. 2, pp. 201-219, 2010