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The objective of this work has been to develop and implement an empirical calculation method for the determination of clinical electron output factors. Electron beams with various energies, field sizes, and source to surface distances using cutouts of varying radii were used to measure dose output at the depth of maximum dose in water. A 30 cm × 30 cm × 17.8 cm water equivalent phantom with a 0.125 cc cylindrical ion-chamber (PTW Model 31010) was used. The calculation model predicted the output factor as a product of the cone factor, radius dependent cutout factor, the effective source to surface distance factor and the area dependent aspect ratio factor. A comparative analysis of clinical cutout output factors, determined through both empirical calculation and direct measurement was performed to evaluate the clinical viability of the calculation method before its implementation in our clinic. A total of 643 output factors for 294 different cutout shapes were determined through both traditional measurement and predictive calculation. Predictive calculation differed from definitive measurement by at most 3.5% for all cases, a majority of cases falling within 1%. The method developed successfully predicts electron output factors on the basis of cutout geometry with accuracy better than 96% for all cases and better then 98% for most cases. This ability holds true for all practical SSD, electron energy, cone, and irregular shape combinations. The method has been clinically implemented and in use at our center since 2007.
Content Type Journal Article
DOI 10.3233/XST-2010-0262
Authors
Daniel A. Johnson, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Salahuddin Ahmad, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Purpose: To investigate the increase in surface dose under immobilization thermoplastic masks by measurements and calculation in the build-up region using Gafchromic films and Monte Carlo simulation.
Materials and methods: Surface doses were measured underneath three thermoplastic masks in open fields using 6 and 18 MV photon beams. These masks are used to immobilize patients for head and neck (H&N), pelvis and thoracic treatment. Gafchromic EBT films were placed on the top of the flat surface of a phantom partially underneath the mask and exposed in open 10 × 10 cm^2 photon fields. The depth doses were calculated using BEAMnrc Monte Carlo code for water-equivalent film detectors with different layers of thickness ranging from 50 μm to 2.5 mm and compared with film measurements.
Results: Surface dose increased by a factor of 3 to 4 underneath the mask relative to the open areas and 6 MV beam delivers more skin dose than 18 MV. H&N mask increased surface dose by a factor of 3 using 18 MV and a factor of 4 using 6 MV. In addition, increase in surface dose depended on the type of the mask, the size of openings, and the amount of stretching performed during the mask preparation. The measured depth doses were compared with BEAMnrc Monte Carlo calculation for water-equivalent detectors using different sizes. The calculated depth dose depended significantly on the thickness of film detector and varies by more than 15% using layer thickness of 2.5 mm compared to 50 μm. Surface doses measured by Gafchromic EBT films agreed within 3% with the Monte Carlo calculations using a small detector layer of 50 μm.
Conclusion: Thermoplastic masks used for patient immobilization can significantly increase skin doses by up to a factor of 4 more than that without the mask using 6 MV beams. The skin reactions resulting from thermoplastic masks should be monitored and corrective measures should be taken during treatment such as partially removing the mask over skin areas with complications and optimizing the skin dose in IMRT planning. Gafchromic EBT films provide accurate skin dosimetry which agrees within 3% with Monte Carlo calculations. Gafchromic EBT film makes an excellent tool for measuring depth doses in the buildup region and these data can be applied for treatment planning calculations and IMRT optimization.
Content Type Journal Article
DOI 10.3233/XST-2010-0263
Authors
Imad Ali, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Chance Matthiesen, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Ozer Algan, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Spencer Thompson, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Carl Bogardus, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Terence Herman, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
Salahuddin Ahmad, Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
The spatial resolution of diagnostic Computed Tomography (CT) has increased substantially, and 3D isotropic sub-millimeter spatial resolution in both axial and helical scan modes is routinely available in the clinic. However, driven by advanced clinical applications, the pursuit for higher spatial resolution and free of aliasing artifacts in diagnostic CT has never stopped. A method to accommodate focal spot wobbling at an arbitrary number of projection views per gantry rotation in CT is presented and evaluated here. The method employs a beta-correction scheme in the row-wise fan-to-parallel rebinning to transform the native cone beam geometry into the cone-parallel geometry under which existing 3D weighted cone beam filtered backprojection algorithms can be utilized for image reconstruction. The experimental evaluation shows that the row-wise fan-to-parallel rebinning with the beta-correction can increase the quantitative in-plane spatial resolution (Modulation Transfer Function) substantially, while the visual spatial resolution can be enhanced significantly. Consequently, the architectural designers of CT scanners are no longer constrained to choosing the number of projection views per rotation determined by gantry geometry. Instead, they can choose the number of projection views per rotation to optimize the trade-offs between in-plane spatial resolution and noise characteristics. Therefore, the presented method is of practical relevance in the architectural design of state-of-the-art diagnostic CT.
Content Type Journal Article
DOI 10.3233/XST-2010-0258
Authors
Xiangyang Tang, Department of Radiology, Emory University School of Medicine, 1701 Uppergate Dr., C5018, Atlanta, GA, USA
Suresh Narayanan, Molecular Imaging & Computed Tomography, GE Healthcare, PO Box 414, W1190, Milwaukee, WI, USA
Jiang Hsieh, Molecular Imaging & Computed Tomography, GE Healthcare, PO Box 414, W1190, Milwaukee, WI, USA
Jed D. Pack, CT & X-ray Systems, Global Research Center, GE, One Research Circle, KW-C1309, Niskayuna, NY, USA
Scott M. Mcolash, Molecular Imaging & Computed Tomography, GE Healthcare, PO Box 414, W1190, Milwaukee, WI, USA
Paavana Sainath, Molecular Imaging & Computed Tomography, GE Healthcare, PO Box 414, W1190, Milwaukee, WI, USA
Roy A. Nilsen, Molecular Imaging & Computed Tomography, GE Healthcare, PO Box 414, W1190, Milwaukee, WI, USA
Basel Taha, Molecular Imaging & Computed Tomography, GE Healthcare, PO Box 414, W1190, Milwaukee, WI, USA
The exterior computed tomography (CT) problem is one kind of truncation problem. It is very ill-posed, so that accurate reconstruction of the attenuation function is hardly possible from real data. Based on projection onto convex sets (POCS) algorithm, total variation minimization (TVM) methods, and C-V model, we develop and investigate a new iterative reconstruction algorithm, which is referred to as subregion-averaged-TVM-POCS (SA-TVM-POCS). Numerical simulations are presented to illustrate the efficiency of the algorithm. The results of this paper can be easily applied to other x-ray CT reconstruction problems.
Content Type Journal Article
DOI 10.3233/XST-2010-0259
Authors
Li Zeng, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing, China
Baodong Liu, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing, China
Linghui Liu, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing, China
Caibing Xiang, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing, China
Taxol (Paclitaxel) is an important natural product for the treatment of solid tumors such as ovarian, breast, non-small-cell lung tumors, and some head and neck carcinomas. Different concentrations of taxol trigger distinct effects on cell death forms. In present study, cell counting kit (CCK-8) assay, confocal fluorescence microscopy imaging, flow cytometry (FCM) and western blotting (WB) analysis were used to analyze the characteristics of cell death induced by low (35 nM) and high (70 μM) concentration of taxol respectively in human lung adenocarcinoma (ASTC-a-1) cells. Our results showed that low concentration of taxol induced cell death dominantly in apoptotic fashion associated with nuclear fragmentation, protein synthesis, phosphatidylserine (PS) externalization, G2/M cell cycle arrest, Bax translocation into mitochondria and caspase-3 activation, whereas high concentration of this drug induced significant cytoplasm vacuolization, mitochondria swelling and paraptosis-like cell death form without protein synthesis that is necessary for paraptosis. Although the mechanism of high concentration of taxol-induced paraptosis-like cell death has not been clear, this finding might have a potential implication for cancer therapy, especially for apoptosis-resistant cancer.
Content Type Journal Article
DOI 10.3233/XST-2010-0261
Authors
Wen-Jing Guo, MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China
Tong-Sheng Chen, MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, South China Normal University, Guangzhou, China
Xiao-Ping Wang, Department of Anesthesiology, The First Affiliated Hospital of Jinan University, Guangzhou, China
Rong Chen, Key Laboratory of Optoelectronic Science and Technology for Medicine, Fujian Normal University, Ministry of Education, Fuzhou, China
To investigate the degrading effects of the physical parameters on the in-line X-ray phase-contrast imaging (XPCi), a simulation tool based on the Fresnel/Kirchhoff diffraction integral was firstly developed with comprehensively considering effects of the source-to-sample (S-S) and sample-to-detector (S-D) distances, the practical characteristics of a polychromatic and finite size source, the point spread function (PSF) of the fluorescent screen and the spatial resolution of the detector on the theoretical phase-contrast pattern. By a comparison between the simulative profile and the experimental one under the commonly-used parameters, an acceptable consistency has been demonstrated in despite of the deviation between the theoretically-predicted contrast (0.188) and the original experimental one (0.12). From the simulations, it is apparently observed that the fine interference pattern has been severely degraded by the finite spatial resolution, and will inevitably be further deteriorated by the system noise in practice. Since the image quality of the X-ray phase-contrast imaging is strongly dependent on the physical parameters of the system, a model-based deblurring procedure to upgrade the image visibility is preferably desired. As a simple restoration way, a Wiener filter was then introduced to offer an optimal tradeoff between the contrast preservation and the noise suppression. Finally, to minimize the deviation resulting from the finite spatial resolution, one-dimensional interpolation was performed by positioning the set square at a tiny angle to the vertical direction. The result after the Wiener-filtering-based deblurring has shown a considerably improved profile visibility: the processed experimental contrast (0.156) increased by 30% as compared to the original one (0.12) in company with the increase in the signal-to-noise ratio (SNR) by 0.9dB. With the trend of the post-filtered experimental contrast to the theoretical one, it could be motivated that higher visibility would be achieved with the introduction of more precise blurring mask and noise spectrum estimation.
Content Type Journal Article
DOI 10.3233/XST-2010-0260
Authors
Shaorun Gong, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, China
Feng Gao, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, China
Zhongxing Zhou, College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin, China
This paper presents a fast hybrid CPU- and GPU-based CT reconstruction algorithm to reduce the amount of back-projection operation using air skipping involving polygon clipping. The algorithm easily and rapidly selects air areas that have significantly higher contrast in each projection image by applying K-means clustering method on CPU, and then generates boundary tables for verifying valid region using segmented air areas. Based on these boundary tables of each projection image, clipped polygon that indicates active region when back-projection operation is performed on GPU is determined on each volume slice. This polygon clipping process makes it possible to use smaller number of voxels to be back-projected, which leads to a faster GPU-based reconstruction method. This approach has been applied to a clinical data set and Shepp-Logan phantom data sets having various ratio of air region for quantitative and qualitative comparison and analysis of our and conventional GPU-based reconstruction methods. The algorithm has been proved to reduce computational time to half without losing any diagnostic information, compared to conventional GPU-based approaches.
Content Type Journal Article
DOI 10.3233/XST-2010-0256
Authors
Byeonghun Lee, School of Computer Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
Ho Lee, School of Computer Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
Yeong Gil Shin, School of Computer Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, Republic of Korea
Taking advantage of Diffusion Weighted Imaging (DWI) to characterize the random movement of water molecules in biological tissue, this article intends to review the Intravoxel Incoherent Motion (IVIM) theory as a valuable method to find the differentiation between malignant and benign tumor based on the microcirculation of blood in the capillaries. IVIM is measured by means of a parameter called apparent diffusion coefficient (ADC). Through the application of IVIM to the imaging processing software, it will be possible to set up an expert system with screening, discrimination, staging and therapeutic evaluation function of tumor.
Content Type Journal Article
Category Review Article
DOI 10.3233/XST-2010-0257
Authors
Cruz Gloria, Department of Biomedical Engineering, Beijing Institute of Technology, Beijing, China
Qin Li, Department of Biomedical Engineering, Beijing Institute of Technology, Beijing, China
Liping Xu, Department of Biomedical Engineering, Beijing Institute of Technology, Beijing, China
Wanshi Zhang, Department of Radiology, Air Force General Hospital, Beijing, China
Synchrotron-based scattered radiation form low-contrast phantom materials prepared from polyethylene, polystyrene, nylon, and Plexiglas is used as test objects in X-ray CT was examined with 8, 10 and 12 keV X-rays. These phantom materials of medical interest will contains varying proportions of low atomic number elements. The assessment will allowed us to estimate the fluorescence to total scattered radiation. Detected the fluorescence spectra and the associated scattered radiation from calcium hydroxyapatite phantom with 8, 10 and 12 keV synchrotron X-rays. Samples with Bonefil (60% and 70% of calcium hydroxyapatite) and Bone cream (35 ∼ 45% of calcium hydroxyapatite), were used. Utilized the X-ray micro-spectroscopy beamline facility, X27A, available at NSLS, BNL, USA. The primary beam with a spot size of the order of ∼ 10 μm, has been used for focusing. With this spatial resolution and high flux throuput, the synchrotron-based scattered radiation from the phantom materials were measured using a liquid-nitrogen-cooled 13-element energy-dispersive high-purity germanium detector.
Content Type Journal Article
Category Technical Report
DOI 10.3233/XST-2010-0255
Authors
Donepudi V. Rao, Istituto di Matematica e Fisica, Università degli Studi di Sassari, Sassari, Italy
Medasani Swapna, Istituto di Matematica e Fisica, Università degli Studi di Sassari, Sassari, Italy
Roberto Cesareo, Istituto di Matematica e Fisica, Università degli Studi di Sassari, Sassari, Italy
Antonio Brunetti, Istituto di Matematica e Fisica, Università degli Studi di Sassari, Sassari, Italy
Tako Akatsuka, Department of Bio-System Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Japan
Tetsuya Yuasa, Department of Bio-System Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Japan
Tohoru Takeda, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Japan
Giovanni E. Gigante, Dipartimento di Fisica, Universita di Roma, "La Sapienza" 00185, Roma, Italy
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0253
Authors
Murat Kurudirek, Faculty of Science, Department of Physics, Ataturk University, Erzurum, Turkey
Yüksel Özdemir, Faculty of Science, Department of Physics, Ataturk University, Erzurum, Turkey
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0252
Authors
Zhanqi Zhao, Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany
Daniel Steinmann, Department of Anesthesiology and Critical Care Medicine, Section for Experimental Anesthesiology, University Medical Center, Freiburg, Germany
Danijela Müller-Zivkovic, Department of Orthopedics and Trauma Surgery, Klinik am Eichert, Göppingen, Germany
Jörg Martin, Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, Klinik am Eichert, Göppingen, Germany
Josef Guttmann, Department of Anesthesiology and Critical Care Medicine, Section for Experimental Anesthesiology, University Medical Center, Freiburg, Germany
Knut Möller, Department of Biomedical Engineering, Furtwangen University, Villingen-Schwenningen, Germany
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0254
Authors
Yüksel Özdemir, Department of Physics, Faculty of Science, Atatürk University, Erzurum, Turkey
Yusuf Ziya Bayındır, Faculty of Dentistry, Atatürk University, Erzurum, Turkey
Doğan Durna, Faculty of Dentistry, Atatürk University, Erzurum, Turkey
Rıdvan Durak, Department of Physics, Faculty of Science, Atatürk University, Erzurum, Turkey
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0249
Authors
Laszlo Papp, Mediso Medical Imaging Systems, Budapest, Hungary
Reka Juhasz, Department of Image Processing and Computer Graphics, University of Szeged, Szeged, Hungary
Sonja Travar, Clinical Center Vojvodina, University of Novi Sad, Novi Sad, Serbia
Alexander Kolli, Research Unit for Digital Information and Image Processing, University Clinic for Radiology, Medical University Graz, Graz, Austria
Erich Sorantin, Research Unit for Digital Information and Image Processing, University Clinic for Radiology, Medical University Graz, Graz, Austria
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0248
Authors
Mehmet Celenk, School of EECS, Ohio University, OH, USA
Mike L. Farrell, School of EECS, Ohio University, OH, USA
Haluk Eren, School of EECS, Ohio University, OH, USA
K. Kumar, School of EECS, Ohio University, OH, USA
G. Dave Singh, BioModeling Solutions, LLC, Beaverton, OR, USA
Scott Lozanoff, University Hawaii at Manoa, Honolulu, HI, USA
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0250
Authors
Sheng Fang, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, P.R. China
Kui Ying, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, P.R. China
Jianping Cheng, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, P.R. China
Shi Wang, Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Department of Engineering Physics, Tsinghua University, Beijing, P.R. China
Jing Zhang, Department of Radiology, General Navy Hospital, Beijing, P.R. China
Zhikui Xiao, Applied Science Laboratory, GE Healthcare China, Beijing, P.R. China
Hao Shen, Applied Science Laboratory, GE Healthcare China, Beijing, P.R. China
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0246
Authors
Changguo Ji, The City Key Lab of Medical Physics and Engineering, Peking University, Beijing, P.R. China. E-mail: jicg@pku.edu.cn
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).
Content Type Journal Article
DOI 10.3233/XST-2010-0247
Authors
R. Durak, Department of Physics, Science Faculty, Atatürk University, Erzurum, Turkey
Y. Gülen, Department of Physics, Science Faculty, Atatürk University, Erzurum, Turkey
M. Kurudirek, Department of Physics, Science Faculty, Atatürk University, Erzurum, Turkey
M. Kaçal, Department of Physics, Science Faculty, Atatürk University, Erzurum, Turkey
İ. Çapoğlu, Department of Internal Medicine, Medicine Faculty, Atatürk University, Erzurum, Turkey
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__{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}_O_{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.
Content Type Journal Article
DOI 10.3233/XST-2010-0245
Authors
A. Bourbia, Laboratory of Magnetism and Spectroscopy of Solids, Physics Department, Faculty of Science, Badji-Mokhtar University, Annaba, Algeria
M. Draissia, Laboratory of Magnetism and Spectroscopy of Solids, Physics Department, Faculty of Science, Badji-Mokhtar University, Annaba, Algeria
H. Bedboudi, Laboratory of Magnetism and Spectroscopy of Solids, Physics Department, Faculty of Science, Badji-Mokhtar University, Annaba, Algeria
S. Boulkhessaim, Laboratory of Magnetism and Spectroscopy of Solids, Physics Department, Faculty of Science, Badji-Mokhtar University, Annaba, Algeria
M.Y. Debili, Laboratory of Magnetism and Spectroscopy of Solids, Physics Department, Faculty of Science, Badji-Mokhtar University, Annaba, Algeria
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.
Content Type Journal Article
DOI 10.3233/XST-2010-0243
Authors
Yong Yang, School of Information Technology, Jiangxi University of Finance and Economics, Nanchang, China
Dong Sun Park, Division of Electronics and Information Engineering, Chonbuk National University, Jeonju, Korea
Shuying Huang, School of Software and Communications Engineering, Jiangxi University of Finance and Economics, Nanchang, China
Jucheng Yang, School of Information Technology, Jiangxi University of Finance and Economics, Nanchang, China
Background and purpose: Radiographic techniques are essential methods of diagnosis, and their use has been increased, especially with the development of the new technologies. Inappropriate administration of these techniques may put both the patients and personnel at unnecessary risks. The objective of this research was to measure the skin dose of chest and skull radiographies used in Mazandaran hospitals and to compare these doses with national and international standards.
Materials and methods: In this cross-sectional study, six X-ray generators at six hospitals affiliated to Mazandaran University of Medical Sciences were included. One hundred and twenty patients referred to the radiology wards for radiographic examinations of chest and skull with normal body mass index (BMI) were selected (20 patients for each radiography unit). The generators were matched for mAs, kvp, type of amplifier sheets, and technical conditions as much as possible. Calibrated thermo luminescence dosimeters (TLD-USA, Lif-100) were used to measure the skin dose by placing them on the patients' back and the absorbed doses by TLDs were read by a TLD reader (model: Harshuu, TLD3500, Japan).
Results: The mean values of the skin dose were 0.51 mGray for posteroanterior (PA), chest X-ray (CXR), 3.36 mGray for lateral CXR, 7.25 mGray for anterroposterior (AP) or PA skull X-rays, and 7.59 mGray for lateral skull X-rays. The measured values were higher than the national and international standards.
Conclusion: The results of this research revealed that the conditions of the X-ray generators should be monitored and modified periodically. Modifying the X-ray generators plus improving technicians' skills would, to some extent, reduce the radiation exposure of the patients.
Content Type Journal Article
Category Status Report
DOI 10.3233/XST-2010-0244
Authors
Siavash Etemadinezhad, Department of Occupational Health, Faculty of Health, Mazandaran University of Medical Sciences, Iran
Seyed Ali Rahimi, Department of Medical Physics, Faculty of Health, Mazandaran University of Medical Sciences, Iran
