scholarly journals Modified kernel MLAA using autoencoder for PET-enabled dual-energy CT

2021 ◽  
Vol 379 (2204) ◽  
pp. 20200204 ◽  
Author(s):  
Siqi Li ◽  
Guobao Wang
Keyword(s):  
Image Reconstruction ◽  
Kernel Method ◽  
High Energy ◽  
Dual Energy ◽  
Feature Representation ◽  
Dual Energy Ct ◽  
Ct Image ◽  
Material Decomposition ◽  
X Ray ◽  
Image Prior

Combined use of PET and dual-energy CT provides complementary information for multi-parametric imaging. PET-enabled dual-energy CT combines a low-energy X-ray CT image with a high-energy γ -ray CT (GCT) image reconstructed from time-of-flight PET emission data to enable dual-energy CT material decomposition on a PET/CT scanner. The maximum-likelihood attenuation and activity (MLAA) algorithm has been used for GCT reconstruction but suffers from noise. Kernel MLAA exploits an X-ray CT image prior through the kernel framework to guide GCT reconstruction and has demonstrated substantial improvements in noise suppression. However, similar to other kernel methods for image reconstruction, the existing kernel MLAA uses image intensity-based features to construct the kernel representation, which is not always robust and may lead to suboptimal reconstruction with artefacts. In this paper, we propose a modified kernel method by using an autoencoder convolutional neural network (CNN) to extract an intrinsic feature set from the X-ray CT image prior. A computer simulation study was conducted to compare the autoencoder CNN-derived feature representation with raw image patches for evaluation of kernel MLAA for GCT image reconstruction and dual-energy multi-material decomposition. The results show that the autoencoder kernel MLAA method can achieve a significant image quality improvement for GCT and material decomposition as compared to the existing kernel MLAA algorithm. A weakness of the proposed method is its potential over-smoothness in a bone region, indicating the importance of further optimization in future work. This article is part of the theme issue ‘Synergistic tomographic image reconstruction: part 2’.

scholarly journals Line Integral Alternating Minimization Algorithm for Dual-Energy X-Ray CT Image Reconstruction

2016 ◽  
Vol 35 (2) ◽  
pp. 685-698 ◽  
Author(s):  
Yaqi Chen ◽  
Joseph A. O'Sullivan ◽  
David G. Politte ◽  
Joshua D. Evans ◽  
Dong Han ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Dual Energy ◽  
Ct Image ◽  
Alternating Minimization ◽  
Minimization Algorithm ◽  
Line Integral ◽  
X Ray ◽  
Alternating Minimization Algorithm ◽  
Ct Image Reconstruction

A dual-energy material decomposition method for high-energy X-ray cargo inspection

2012 ◽  
Vol 61 (5) ◽  
pp. 821-824 ◽  
Author(s):  
Jiseoc Lee ◽  
Yunjeong Lee ◽  
Seungryong Cho ◽  
Byung-Cheol Lee
Keyword(s):  
Decomposition Method ◽  
High Energy ◽  
Dual Energy ◽  
Material Decomposition ◽  
X Ray ◽  
Energy Material ◽  
Cargo Inspection

scholarly journals Feasibility of Dect Imaging in material separation: A Phantom Study

2019 ◽  
Vol 10 (SPL1) ◽  
Author(s):  
Zuraida Ramli ◽  
Rafidah Zainon ◽  
Abd Aziz Tajuddin ◽  
Nur Shakila Othman
Keyword(s):  
Clinical Practice ◽  
Calcium Chloride ◽  
High Energy ◽  
Dual Energy ◽  
Dual Energy Ct ◽  
Ferric Nitrate ◽  
Slice Thickness ◽  
X Ray ◽  
Wide Range ◽  
Material Separation

Dual-energy CT allows the determination of tissue composition based on the different atomic numbers and attenuation profiles of the constituents. The aims of this study is to assess the feasibility of dual-energy CT at Imaging Unit, Advanced Medical, and Dental Institute, USM, to quantify different materials, permitting imaging assessment of elemental deficiencies, metabolic imbalances, and any abnormal tissue in clinical practice. The study was conducted at the Imaging Unit, Advanced Medical and Dental Institute, Universiti Sains Malaysia, Pulau Pinang, Malaysia. The study was performed using a new fabricated abdominal phantom for spectral CT imaging that scanned on the single-source, fast switching dual-energy CT scanner (Somatom Definition; Siemens AG, Wittelsbacherplatz Muenchen, Germany) system in dual-energy mode at tube voltages of 80 kVp for low energy and 140 kVp for high energy using abdominal protocol. The phantom was scanned at 4.0 mm slice thickness and pitch value 1.2 using CAREDose 4D (automated tube current modulation). Four tubes filled with calcium chloride, ferric nitrate, water, and sunflower oil that represents bone, blood, soft tissue, and fat respectively were analyzed in an abdominal phantom. Image post-processing was analyzed. All the tissue-mimicking materials, calcium chloride, ferric nitrate, water, and oil can be differentiated clearly in an unenhanced image scan. By applying the two different energy levels, all these materials can be accurately differentiated from one another based on their differential absorption levels of the x-ray energy. The material separation in the dual-energy CT technique is based on the attenuation interaction in the irradiated materials by applying varies x-ray beam at low and high energy. Furthermore, in clinical practice, a radiation source is usually composed of individual photons with a wide range of energies, and each photon energy is attenuated differently by the types of tissues in the human body. Material separation can be accurately quantified with a dual-energy CT system available at Universiti Sains Malaysia. Thus, the dual-energy CT capable of tissue characterization.  

A Spectrum-Adaptive Decomposition Method for Effective Atomic Number Estimation Using Dual Energy CT

2020 ◽  
Vol 2020 (14) ◽  
pp. 293-1-293-7
Author(s):  
Ankit Manerikar ◽  
Fangda Li ◽  
Avinash C. Kak
Keyword(s):  
Atomic Number ◽  
Decomposition Method ◽  
Traditional Approach ◽  
Effective Atomic Number ◽  
Dual Energy ◽  
Performance Comparison ◽  
Estimation Methods ◽  
Dual Energy Ct ◽  
Projection Data ◽  
X Ray

Dual Energy Computed Tomography (DECT) is expected to become a significant tool for voxel-based detection of hazardous materials in airport baggage screening. The traditional approach to DECT imaging involves collecting the projection data using two different X-ray spectra and then decomposing the data thus collected into line integrals of two independent characterizations of the material properties. Typically, one of these characterizations involves the effective atomic number (Zeff) of the materials. However, with the X-ray spectral energies typically used for DECT imaging, the current best-practice approaches for dualenergy decomposition yield Zeff values whose accuracy range is limited to only a subset of the periodic-table elements, more specifically to (Z < 30). Although this estimation can be improved by using a system-independent ρe — Ze (SIRZ) space, the SIRZ transformation does not efficiently model the polychromatic nature of the X-ray spectra typically used in physical CT scanners. In this paper, we present a new decomposition method, AdaSIRZ, that corrects this shortcoming by adapting the SIRZ decomposition to the entire spectrum of an X-ray source. The method reformulates the X-ray attenuation equations as direct functions of (ρe, Ze) and solves for the coefficients using bounded nonlinear least-squares optimization. Performance comparison of AdaSIRZ with other Zeff estimation methods on different sets of real DECT images shows that AdaSIRZ provides a higher output accuracy for Zeff image reconstructions for a wider range of object materials.

scholarly journals Combination of Dual-Energy X-ray Transmission and Variable Gas-Ejection for the In-Line Automatic Sorting of Many Types of Scrap in One Measurement

2021 ◽  
Vol 11 (10) ◽  
pp. 4349
Author(s):  
Tianzhong Xiong ◽  
Wenhua Ye ◽  
Xiang Xu
Keyword(s):  
High Efficiency ◽  
Nearest Neighbor ◽  
High Energy ◽  
Dual Energy ◽  
Center Of Gravity ◽  
Low Energy ◽  
Identification Accuracy ◽  
Flow Process ◽  
X Ray ◽  
Automatic Sorting

As an important part of pretreatment before recycling, sorting has a great impact on the quality, efficiency, cost and difficulty of recycling. In this paper, dual-energy X-ray transmission (DE-XRT) combined with variable gas-ejection is used to improve the quality and efficiency of in-line automatic sorting of waste non-ferrous metals. A method was proposed to judge the sorting ability, identify the types, and calculate the mass and center-of-gravity coordinates according to the shading of low-energy, the line scan direction coordinate and transparency natural logarithm ratio of low energy to high energy (R_value). The material identification was satisfied by the nearest neighbor algorithm of effective points in the material range to the R_value calibration surface. The flow-process of identification was also presented. Based on the thickness of the calibration surface, the material mass and center-of-gravity coordinates were calculated. The feasibility of controlling material falling points by variable gas-ejection was analyzed. The experimental verification of self-made materials showed that identification accuracy by count basis was 85%, mass and center-of-gravity coordinates calculation errors were both below 5%. The method proposed features high accuracy, high efficiency, and low operation cost and is of great application value even to other solid waste sorting, such as plastics, glass and ceramics.

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