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This study introduces a method to reduce the artefact caused by metal implant, and improve the image quality. The factors affecting the image quality of the existing methods are analysed from a different point of view. The observed projection is decomposed into several components including the correspondence of biological tissues, the correspondence of metal implant, noises, and inconsistencies caused by beam hardening. The correspondence of metal implant is identified by initial reconstruction and forward modelling, and the noises are detected and isolated from the projection in wavelet domain. The inconsistencies are approximated and compensated. A patient with medial epicondyle of right femur replaced using femoral component made by Biomet Inc was scanned using a GE Lightspeed 16 X-ray CT scanner and the observed projection is processed by this method. The output image shows that all of the streaking caused by metal implant is eliminated, and the darkness areas caused by beam hardening are retrieved. Comparing with the default output of the CT scanner, the image quality has been significantly improved.
Content Type Journal Article
DOI 10.3233/XST-2009-0235
Authors
Julian J. Liu, Medical Physics Department, Royal Sussex County Hospital, Brighton BN2 5BE, UK
John E. Lutkin, Medical Physics Department, Royal Sussex County Hospital, Brighton BN2 5BE, UK
The physical performance of two Flat Panel Detectors has been evaluated. The first Flat Panel Detector is for Fluoroscopic applications, Varian PaxScan 2520, and the second is for Cone Beam Computer Tomography applications, Varian PaxScan 4030CB. First, the spectrum of the X-ray source was measured. Second, the linearity of the detectors was investigated by using an ionization chamber and the average ADU values of the detectors. Third, the temporal resolution was characterized by evaluating their image lag. Fourth, their spatial resolution was characterized by the pre-sampling Modulation Transfer Function. Fifth, the Normalized Noise Power Spectrum was calculated for various exposures levels. Finally, the Detective Quantum Efficiency was obtained as a function of spatial frequency and entrance exposure. The results illustrate that the physical performance in Detective Quantum Efficiency and Normalized Noise Power Spectrum of the Cone Beam Computer Tomography detector is superior to that of the fluoroscopic detector whereas the latter detector has a higher spatial resolution as demonstrated by larger values of its Modulation Transfer Function at large spatial frequencies.
Content Type Journal Article
DOI 10.3233/XST-2009-0234
Authors
Ricardo Betancourt BenĂtez, Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA
Ruola Ning, Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA
David Conover, Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA
Shaohua Liu, Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA
This study compared patient dose and image quality of a mobile O-arm™ cone beam imaging system in the 3D scan acquisition mode to those of a 64 slice Computed Tomography (CT) imaging system. The investigation included patient dose, scattered radiation, and image quality measurements. The patient dose was measured using a 0.6cc Farmer ion chamber and 30cm long Computed Tomography (CT) head and body polymethylmethacrylate (PMMA) phantoms. The results show that under identical radiographic techniques (kVp, mAs, etc.) and with the same scan length, the O-arm™ in 3D scan acquisition mode delivers approximately half the radiation dose of a 64 slice CT scanner. Scattered radiation was measured at several locations around the O-arm™, at 1 m, 2 m and 3 m distances in 3D CT scan acquisition mode with a RadCal 10 × 5–180 pancake ion chamber using a 30 cm long CT body phantom as the source of scatter. Similar measurements were made in a 64 slice CT scanner. The data demonstrate that scattered radiation from the O-arm™ to personnel involved in a clinical procedure is comparable to that from a 64 slice CT scanner. Image quality was compared by exposing a CATPHAN phantom to comparable doses in both the O-arm™ and the CT scanner. The resultant images were then evaluated for modulation transfer function (MTF), high-contrast spatial resolution, and low contrast sensitivity for clinical application purpose. The O-arm™ shows comparable high contrast to the CT (7 lp/cm vs. 8 lp/cm). The low contrast in the O-arm™ is not visible due to fixed pattern noise. For image guided surgery applications where the location of a structure is emphasized over a survey of all image details, the O-arm™ has some advantages due to wide radiation beam coverage and lower patient dose. The image quality of the O-arm™ needs significant improvement for other clinical applications where high image quality is desired.
Content Type Journal Article
DOI 10.3233/XST-2009-0231
Authors
Jie Zhang, Medical Physics Section, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
Victor Weir, Medical Physics Section, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
Liliosa Fajardo, Medical Physics Section, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
Jingying Lin, Medical Physics Section, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
Hsiang Hsiung, Medical Physics Section, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
E. Russell Ritenour, Medical Physics Section, Department of Radiology, University of Minnesota, Minneapolis, MN, USA
In Cone Beam Breast CT (CBBCT) imaging, noise causes degradation of three dimensional breast images, impeding correct diagnosis of breast cancer. Within Feldkamp's cone beam reconstruction framework, applying weighted reconstruction filters to the projection images after pre-processing procedures has long been used to reduce noise and improve image quality. However, CBBCT noise is distributed across frequencies along with the useful signal. Various reconstruction filters working in the frequency domain suppress noise as well as the edge detail signal. Based on fuzzy c-means clustering and the two-dimensional histogram analysis of a large number of clinical CBBCT data, we managed to discriminate fatty stroma, glandular tissues and the transition areas between these tissues by the local mean and standard deviation values. We also proposed a three-dimensional Gaussian filtering scheme to reduce the noise in 3D reconstructed images adaptively without much blurring of detail signal.
Content Type Journal Article
DOI 10.3233/XST-2009-0232
Authors
Xiaohua Zhang, Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
Ruola Ning, Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
Dong Yang, Department of Imaging Sciences, University of Rochester, Rochester, NY, USA
The objective of this work was to assess the relative impact of radiobiological parameters and radiation dose escalation on Tumor Control Probability for prostate cancer patients treated with radiation. Radiobiological parameters included α/β ratios, cell surviving fraction at 2 Gy (SF_{2}) and clonogenic cell density (CCD). Using the Niemierko method, TCP was calculated in ten prostate cancer patients as a function of increasing radiation doses (70–140 Gy), α/β ratios (1.5–20), SF_{2} (0.3–0.7) and CCD (10–20 million cells/cm^{3}). At 70 Gy and CCD of 10 million/cm^{3}, TCP was above 99% for SF_{2} of 0.3 or 0.4, 97.4%–98.6% for SF_{2} of 0.5 and less than 2% for SF_{2} of 0.6 or 0.7. With dose escalation, TCP values above 99% were demonstrated at 80 Gy for SF_{2} of 0.5 and 100 Gy for SF_{2} of 0.6. For SF_{2} of 0.7, TCP above 99% was demonstrated with 100 Gy and CCD of 10^{4} cells/cm^{3} or 140 Gy and CCD of 10^{7} cells/cm^{3}. TCP decreased with lower α/β of 1.5, but at a much smaller scale compared to SF_{2} changes. TCP modeling predicts that SF_{2} and CCD are dominant predictors of radioresistance in prostate cancer. Radiation doses of 100 Gy or greater may be required for tumors with SF_{2} of 0.6 or above. Relating clinical tumor prognostic indicators such as Gleason score and PSA to radiobiological parameters will allow us to identify subsets of patients in need of higher radiation doses and adjuvant therapy to maximize treatment outcomes.
Content Type Journal Article
DOI 10.3233/XST-2009-0233
Authors
Salahuddin Ahmad, University of Oklahoma Health Sciences Center, Oklahoma City, USA
Betty J. Vogds, University of Oklahoma Health Sciences Center, Oklahoma City, USA
Fred McKenna, University of Oklahoma Health Sciences Center, Oklahoma City, USA
Maria T. Vlachaki, Wayne State University School of Medicine, Detroit, USA
In the computed tomography (CT) field, one recent invention is the so-called carbon nanotube (CNT) based field emission x-ray technology. On the other hand, compressive sampling (CS) based interior tomography is a new innovation. Combining the strengths of these two novel subjects, we apply the interior tomography technique to local mouse cardiac imaging using respiration and cardiac gating with a CNT based micro-CT scanner. The major features of our method are: (1) it does not need exact prior knowledge inside an ROI; and (2) two orthogonal scout projections are employed to regularize the reconstruction. Both numerical simulations and in vivo mouse studies are performed to demonstrate the feasibility of our methodology.
Content Type Journal Article
DOI 10.3233/XST-2009-0230
Authors
Hengyong Yu, Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA, USA
Guohua Cao, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
Laurel Burk, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
Yueh Lee, Department of Radiology, University of North Carolina, Chapel Hill, NC, USA
Jianping Lu, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
Pete Santago, Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA, USA
Otto Zhou, Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC, USA
Ge Wang, Biomedical Imaging Division, VT-WFU School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA, USA
Today's imaging diagnosis needs to adapt modern techniques of quality engineering to maintain and improve its accuracy and reliability in health care system. One of the main factors that influences diagnostic accuracy of plain film X-ray on detecting pathology is the level of film exposure. If the level of film exposure is not adequate, a normal body structure may be interpretated as pathology and vice versa. This not only influences the patient management but also has an impact on health care cost and patient's quality of life. Therefore, providing an accurate and high quality image is the first step toward an excellent patient management in any health care system. In this paper, we study these techniques and also present a fuzzy intelligent quality monitoring model, which can be used to keep variables from degrading the image quality. The variables derived from chemical activity, cleaning procedures, maintenance, and monitoring may not be sensed, measured, or calculated precisely due to uncertain situations. Therefore, the Îł-level fuzzy Bayesian model for quality monitoring of an image processing is proposed. In order to apply the Bayesian concept, the fuzzy quality characteristics are assumed as fuzzy random variables. Using the fuzzy quality characteristics, the newly developed model calculates the degradation risk for image processing. A numerical example is also presented to demonstrate the application of the model.
Content Type Journal Article
DOI 10.3233/XST-2009-0228
Authors
Azadeh Khalatbari, Department of Medicine, University of Ottawa, Ottawa, Canada
Kouroush Jenab, Department of Mechanical and Industrial Engineering, Ryerson University, Toronto, Canada
An ultra-precision ELID grinding of large stamping dies of Wolter mirror for X-ray telescope was presented in this paper. The large stamping dies (S55C) with confocal paraboloid and hyperboloid was ground by ELID arc-enveloped grinding. In this ELID grinding system, cast iron fiber bonded (CIFB) diamond wheels were controlled by 3-dimentional ways to scan the work-piece and generate required surfaces. Its grinding characteristics such as attainable form accuracy, surface roughness were investigated. Furthermore, some measures to improve form accuracy were discussed and verified such as truing, compensating, and on-machine measuring.
Content Type Journal Article
DOI 10.3233/XST-2009-0227
Authors
Shaohui Yin, National Engineering Research Center for High Efficiency Grinding, Hunan University, Changsha, Hunan 410082, P.R. China
Hitoshi Ohmori, RIKEN (The Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
Qing Liu, National Engineering Research Center for High Efficiency Grinding, Hunan University, Changsha, Hunan 410082, P.R. China
Shinnya Morita, RIKEN (The Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
Fengjun Chen, National Engineering Research Center for High Efficiency Grinding, Hunan University, Changsha, Hunan 410082, P.R. China
Muneaki Asami, RIKEN (The Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan
Yufeng Fan, National Engineering Research Center for High Efficiency Grinding, Hunan University, Changsha, Hunan 410082, P.R. China
In Energy Dispersive X-Ray diffraction measurements, the estimate of momentum transfer q, on which the diffracted intensity depends, should be as accurate as possible. Since q, in turn, depends on both the energy and the scattering angle, an error on the latter due to an incorrect positioning of the sample, to the asymmetric angular spread induced by the collimation slits or, in general, to any uncertainty on the geometric setup, results in an uncertainty on the q value. Here, a new self calibration method to correct such errors, based on a genetic algorithm is presented. It is robust, fast and completely automatic. Results obtained by carrying out Energy Dispersive X-Ray Diffraction measurements on reference samples are reported and discussed. They show how the application of such genetic algorithm may provide a fast esteem of the two parameters required when multiple angle pattern collection is performed, namely the effective starting angle and the angular step. In this way, reliable q-values of all the diffraction pattern features (Bragg peaks for crystalline, and diffused bumps for non-crystalline samples) are obtained.
Content Type Journal Article
DOI 10.3233/XST-2009-0226
Authors
A. Brunetti, Struttura Dipartimentale di Matematica e Fisica, UniversitĂ di Sassari, 07100, Sassari, Italy
V. Rossi Albertini, Istituto di Struttura della Materia, CNR, Rome, Italy
D. Bailo, Istituto di Struttura della Materia, CNR, Rome, Italy
In cone beam industrial computed tomography (ICT), it is often required to inspect the large object using flat detector. If traditional helical scanning is used, the field of view (FOV) is limited due to the size of flat detector. As an alternative, a dual helical cone-beam scanning is proposed in this paper. Before each helical scanning, x-ray source and flat detector are horizontally translated a given distance, and part of the object is covered by x-ray at each view angle. Then the object function is reconstructed by use of the improved helical FDK algorithm, which does not rebin projection data. Simulations validate that the images, which are reconstructed by proposed scanning mode and improved algorithm with small flat detector, are similar to those from the conventional helical scanning and FDK algorithm with large flat detector. The improved FDK algorithm is not sensitive to translation step. Furthermore, the proposed scanning mode can extend the radius of FOV up to at least 1.7 times.
Content Type Journal Article
DOI 10.3233/XST-2009-0225
Authors
Xiaobing Zou, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing 400044, China
Li Zeng, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing 400044, China
Zongjian Li, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing 400044, China
Linear scan cone-beam Computed Tomography (CT) is useful to fixed pipeline inspection. We extend Simultaneous Algebraic Reconstruction Technique (SART) to linear scan cone-beam CT and focus on reducing its reconstruction time through cluster computing. In order to reduce communication overhead, we investigate a trapeziform image space decomposition scheme and a subsets-reduce communication technique. The performance of proposed parallel algorithm is analyzed theoretically and verified through experiment. The results show that the proposed parallel algorithm can generate approving CT images and its performance is mainly influenced by load imbalance and network bandwidth.
Content Type Journal Article
DOI 10.3233/XST-2009-0224
Authors
Baodong Liu, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing, 400044, China
Li Zeng, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing, 400044, China
Non-circular scanning geometries such as helix or circular sinusoid have been used or proposed for cone-beam computed tomography (CBCT), because they provide sufficient data for numerically stable and exact image reconstruction within the scanned volume. Analytic algorithms have been developed for image reconstruction from cone-beam data acquired with a full-scan circular sinusoidal trajectory. In this work, we propose an innovative imaging approach in which a reduced-scan circular sinusoidal trajectory is used for acquiring data sufficient for exact 3D image reconstruction. A filtered backprojection (FBP) algorithm based on Pack-Noo's reconstruction formula is applied for image reconstruction in reduced-scan circular sinusoidal scans. We have conducted numerical studies to demonstrate the reduced-scan approach and to validate the FBP reconstruction algorithm in the proposed approach. The proposed scanning method can contribute to increasing the throughput of a scanner, while improving the image quality compared to a conventional circular scan.
Content Type Journal Article
DOI 10.3233/XST-2009-0222
Authors
Dan Xia, Radiology Department, The University of Chicago, Chicago, IL, USA
Seungryong Cho, Radiology Department, The University of Chicago, Chicago, IL, USA
Xiaochuan Pan, Radiology Department, The University of Chicago, Chicago, IL, USA
Multiresolution Analysis (MRA) plays an important role in image and signal processing fields, and it can extract information at different scales. Image fusion is a process of combining two or more images into an image, which extracts features from source images and provides more information than one image. The research presented in this article is aimed at the development of an automated imaging enhancement system in digital radiography (DR) images, which can clearly display all the defects in one image and don't bring blocking effect. In terms of characteristic of the collected radiographic signals, in the proposed scheme the subsection of signals is mapped to 0–255 gray scale to form several gray images and then these images are fused to form a new enhanced image. This article focuses on comparing the discriminating power of several multiresolution images decomposing methods using contrast pyramid, wavelet, and ridgelet respectively. The algorithms are extensively tested and the results are compared with standard image enhancement algorithms. Tests indicate that the fused images present a more detailed representation of the x-ray image. Detection, recognition, and search tasks may therefore benefit from this.
Content Type Journal Article
DOI 10.3233/XST-2009-0223
Authors
Kuan Shen, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing 400030, China
Yumei Wen, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing 400030, China
Yufang Cai, ICT Research Center, Key Laboratory of Optoelectronic Technology and System of the Education Ministry of China, Chongqing University, Chongqing 400030, China
Micro-CT imaging of objects at very high magnification runs into the problem of small geometric movements of the x-ray emission spot relative to the object, thermally induced or otherwise, causing magnified shifts in the projection images during scanning. This produces movement artefacts in the reconstructed images. Here a technique is described to correct such movements by adding a short reference scan at the end of a high magnification scan, with a very large rotation step. Where geometry changes during a scan are slow, such movements can be considered minimal during this very short "post-scan". Registration of the post-scan images with corresponding images in the main scan allow X/Y pixel shifts in the projection images associated with the geometry movement to be calculated, and corrected during reconstruction. This post-scan correction method was applied here to scans of three small objects, all with a voxel size less than one micron, in a desktop micro-CT and a nano-CT scanner. The method substantially reduced movement artefacts from the reconstructed images, improving image quality and resolution. Where the geometry movement results largely from thermal movement of the x-ray micro-focus emission spot, the post-scan method allows the reconstruction of the spatio-temporal trajectory of this spot movement.
In this paper, we present the preliminary experimental results on controlled cardiac computed tomography (CT), which aims to reduce the motion artifacts by means of controlling the x-ray source rotation speed. An innovative cardiac phantom enables us to perform this experiment without modifying the scanner. It is the first experiment on the cardiac CT with speed controlled x-ray source. Experimental results demonstrate that the proposed method successfully separates the phantom images at different phases (improve the temporal resolution) through controlling the x-ray speed.
Content Type Journal Article
DOI 10.3233/XST-2009-0221
Authors
Yang Lu, VT-WFU School of Biomedical Engineering & Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
Zhijun Cai, Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA 52242, USA
Ge Wang, VT-WFU School of Biomedical Engineering & Sciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, USA
Jun Zhao, Department of Biomedical Engineering, Shanghai JiaoTong University, Shanghai 200240, China
Er-Wei Bai, Department of Electrical and Computer Engineering, University of Iowa, Iowa City, IA 52242, USA
This paper defines the exact conditions for the application of a previously proposed, general, non-astigmatic, imaging scheme, consisting of a matched pair of spherically bent crystals or reflectors, to x rays. These conditions lead to two specific experimental arrangements, of which one can provide large magnifications. Potential applications include the x-ray diagnosis of laser-produced plasmas and x-ray imaging of, e.g., biological samples, using the highly monochromatic radiation at synchrotron light sources. The results obtained for x rays are, however, valid for a wide spectrum of the electromagnetic radiation so that, for instance, an application of one of the imaging schemes to lithography in the EUV wavelength range should also be possible, if the spherically bent crystals are replaced by appropriate spherical reflectors. Also described is the design of an x-ray crystal spectrometer, which meets the here defined, necessary requirements for the observation of the x-ray spectra of helium-like argon.
Content Type Journal Article
DOI 10.3233/XST-2009-0219
Authors
M. Bitter, Princeton University, Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA
K.W. Hill, Princeton University, Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA
F. Jones, Princeton University, Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA
S. Scott, Princeton University, Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA
High-energy X-ray computed tomography (CT) systems have been recently used to produce high-resolution images in various nondestructive testing and evaluation (NDT/NDE) applications. The accuracy of the dimensional information extracted from CT images is rapidly approaching the accuracy achieved with a coordinate measuring machine (CMM), the conventional approach to acquire the metrology information directly. On the other hand, CT systems generate the sinogram which is transformed mathematically to the pixel-based images. The dimensional information of the scanned object is extracted later by performing edge detection on reconstructed CT images. The dimensional accuracy of this approach is limited by the grid size of the pixel-based representation of CT images since the edge detection is performed on the pixel grid. Moreover, reconstructed CT images usually display various artifacts due to the underlying physical process and resulting object boundaries from the edge detection fail to represent the true boundaries of the scanned object.
In this paper, a novel algorithm to reconstruct the boundaries of an object with uniform material composition and uniform density is presented. There are three major benefits in the proposed approach. First, since the boundary parameters are reconstructed instead of image pixels, the complexity of the reconstruction algorithm is significantly reduced. The iterative approach, which can be computationally intensive, will be practical with the parametric boundary reconstruction. Second, the object of interest in metrology can be represented more directly and accurately by the boundary parameters instead of the image pixels. By eliminating the extra edge detection step, the overall dimensional accuracy and process time can be improved. Third, since the parametric reconstruction approach shares the boundary representation with other conventional metrology modalities such as CMM, boundary information from other modalities can be directly incorporated as prior knowledge to improve the convergence of an iterative approach. In this paper, the feasibility of parametric boundary reconstruction algorithm is demonstrated with both simple and complex simulated objects. Finally, the proposed algorithm is applied to the experimental industrial CT system data.
Content Type Journal Article
DOI 10.3233/XST-2009-0217
Authors
Zhye Yin, GE Global Research, Niskayuna, NY 12309, USA
Kedar Khare, GE Global Research, Niskayuna, NY 12309, USA
Bruno De Man, GE Global Research, Niskayuna, NY 12309, USA
Traditional reconstruction algorithm in computed tomography (CT) requires a square reconstruction matrix, regardless of the particular object shape. This becomes inefficient when reconstructing planar objects such as IC chips which have a large area-to-thickness ratio. This article presents a differential reconstruction algorithm for planar object CT scan. By automatically determining the scanning start orientation of the object and its tilting angle with respect to the rotation axis, a reconstruction matrix with different dimensions and/or different reconstruction resolutions is employed to reconstruct the object area only. For demonstration, a low-temperature co-fire ceramic (LTCC) component is scanned and reconstructed. It shows that the new method requires much less computation time and storage, can achieve higher reconstruction resolution in the thickness dimension, and makes layer separation much easier for multilayer objects.
Content Type Journal Article
DOI 10.3233/XST-2009-0216
Authors
Tong Liu, Singapore Institute of Manufacturing Technology, Singapore
Jian Xu, Singapore Institute of Manufacturing Technology, Singapore
This paper presents a novel data sufficiency condition that unique and stable ROI reconstruction can be achieved from a more flexible family of data sets. To the interior problem, it allows the ROI (Region-of-interest) can be reconstructed from the line integrals passing through this ROI and a small region B located anywhere as long as the image is known on B. Especially, ROI reconstruction can be achieved without any other a priori knowledge when region B is placed outside the object support. We also develop a general reconstruction algorithm with the DBP-POCS (Differentiated backprojection-projection onto convex sets) method. Finally, both numerical and real experiments were done to illustrate the new data sufficiency condition and the good stability of the ROI reconstruction algorithm.
Content Type Journal Article
DOI 10.3233/XST-2009-0218
Authors
Liang Li, Department of Engineering Physics, Tsinghua University, Beijing, 100084, China. and Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, China
Kejun Kang, Department of Engineering Physics, Tsinghua University, Beijing, 100084, China. and Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, China
Zhiqiang Chen, Department of Engineering Physics, Tsinghua University, Beijing, 100084, China. and Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, China
Li Zhang, Department of Engineering Physics, Tsinghua University, Beijing, 100084, China. and Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, China
Yuxiang Xing, Department of Engineering Physics, Tsinghua University, Beijing, 100084, China. and Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, China
Three-dimensional point-kernel multiple scatter model for radiography simulation, based on dose X-ray buildup factors, is proposed and validated to Monte Carlo simulation. This model embraces nonuniform attenuation in object of imaging (patient body tissue). Photon multiple scattering is treated as in the point-kernel integration gamma ray shielding problems via scatter voxels. First order Compton scattering is described by means of Klein-Nishina formula. Photon multiple scattering is accounted by using dose buildup factors. The proposed model is convenient in those situations where more exact techniques, like Monte Carlo, are not time consuming acceptable.
Content Type Journal Article
DOI 10.3233/XST-2009-0215
Authors
Predrag Marinković, Faculty of Electrical Engineering, University of Belgrade, 11120 Belgrade, Republic of Serbia
Radovan Ilić, Vinča Institute of Nuclear Science, Physics Laboratory (010), 11001 Belgrade, Republic of Serbia
