Influence of different path length computation models and iterative reconstruction algorithms on the quality of transmission reconstruction in Tomographic Gamma Scanning

2017 ◽  
Vol 861 ◽  
pp. 16-22 ◽  
Author(s):  
Miaomiao Han ◽  
Zhirong Guo ◽  
Haifeng Liu ◽  
Qinghua Li
Keyword(s):  
Iterative Reconstruction ◽  
Path Length ◽  
Reconstruction Algorithms ◽  
Quality Of Transmission ◽  
Gamma Scanning

scholarly journals Variable Weighted Ordered Subset Image Reconstruction Algorithm

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
Jinxiao Pan ◽  
Tie Zhou ◽  
Yan Han ◽  
Ming Jiang
Keyword(s):  
Numerical Simulation ◽  
Iterative Reconstruction ◽  
Reconstruction Algorithm ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Reconstruction Algorithms ◽  
Ct Data ◽  
Simultaneous Algebraic Reconstruction Technique ◽  
Algebraic Reconstruction

We propose two variable weighted iterative reconstruction algorithms (VW-ART and VW-OS-SART) to improve the algebraic reconstruction technique (ART) and simultaneous algebraic reconstruction technique (SART) and establish their convergence. In the two algorithms, the weighting varies with the geometrical direction of the ray. Experimental results with both numerical simulation and real CT data demonstrate that the VW-ART has a significant improvement in the quality of reconstructed images over ART and OS-SART. Moreover, both VW-ART and VW-OS-SART are more promising in convergence speed than the ART and SART, respectively.

scholarly journals The results of approbation of a comprehensive expert assessment of the quality of CT images of the chest obtained on low-dose scanning protocols using iterative reconstruction methods

2021 ◽  
Vol 12 (3) ◽  
pp. 54-71
Author(s):  
G. V. Berkovich ◽  
A. V. Vodovatov ◽  
L. A. Chipiga ◽  
G. E. Trufanov
Keyword(s):  
Iterative Reconstruction ◽  
Low Dose ◽  
Ct Images ◽  
Expert Assessment ◽  
Reconstruction Algorithms ◽  
Suspected Infection ◽  
Reconstruction Methods ◽  
Method Of Assessment ◽  
Ct Image Quality

Introduction. Сomputed tomography (CT) is associated with high individual patient doses. Hence, the process of optimization in CT examinations by developing low-dose scan protocols is important.Purpose of the study. Clinical approbation of low-dose protocols developed by the authors earlier, selection of the most promising protocol, assessment of the applicability of the developed algorithm for expert assessment of the quality of CT images.Materials and methods. The study was based on the data from 96 patients who underwent cardiac surgery with suspected infection in the lungs or sternal wound infection. CT examinations were performed using standard, low-dose and ultra-low-dose protocols (effective dose 3,5±0,9, 1,7±0,1 and 0,8±0,1 mSv, respectively) using two iterative reconstruction algorithms (IMR and iDose). The quality of the obtained data was assessed by 5 radiologists with more than 5-year experience in chest radiology.Results. In terms of the number of misinterpretations, no significant differences were estimated between the standard and lowdose protocols for all reconstruction methods. The ultra-low-dose protocol was characterized by a significantly higher number of missing lesions compared to other protocols.Conclusion. The developed method of assessment of the CT image quality has proven to be informative and reproducible and can be used to assess new scanning protocols.

scholarly journals The influence of model iterative reconstruction on image quality in standard and low-dose computer tomography of the chest. experimental study.

2020 ◽  
Author(s):  
Антон Yu. Silin ◽  
Ivan S. Gruzdev ◽  
Sergey P. Morozov
Keyword(s):  
Radiation Dose ◽  
Dose Reduction ◽  
Spatial Resolution ◽  
Iterative Reconstruction ◽  
Low Dose ◽  
Reconstruction Algorithms ◽  
Anthropomorphic Phantom ◽  
Pulmonary Lesions ◽  
Calibration Phantom

Background: One of the ways to reduce the radiation dose in CT is to improve image reconstruction algorithms. The latest offer from scanner manufacturers is Model Iterative Reconstruction (MIR). Aims: To compare the quality of visualization of the structures of the organs of the chest and to prove the effectiveness of the low-dose protocol with iterative model reconstruction. Materials and methods: A calibration phantom with a spatial resolution module and an anthropomorphic phantom of the upper body of an adult with nodules in the lungs was scanned on two CT scanners of different manufacturers using the standard dose protocol (SDCT) with algorithms of hybrid iterative reconstruction (HIR) of images and MIR and low-dose protocol (LDCT) and MIR algorithm. The quality of the obtained images was evaluated by the parameters: noise (SD), the contrast-to-noise ratio (CNR), spatial resolution and visualization of pulmonary nodules. The radiation dose was calculated according to the scanner data, the data of individual dosimeters placed on the anthropomorphic phantom, and using a dosimetric phantom. Results: The average SD was 11.5; 24.4 and 21.6; CNR 85.47; 40.6 and 45.6; spatial resolution 2 mm; 2 mm and 3 mm for SDCT with MIR, SDCT with HIR and LDCT with MIR, respectively. Visualization of pulmonary lesions remained excellent in all cases. The radiation dose in case of SDCT was 2.7, and in case of LDCT - 0.67 mSv. The dose reduction was confirmed by dosimeter data. Similar results were obtained by repeating the experiment on a second scanner. Conclusions: The average SD was 11.5; 24.4 and 21.6; CNR 85.47; 40.6 and 45.6; spatial resolution 2 mm; 2 mm and 3 mm for SDCT with MIR, SDCT with HIR and LDCT with MIR, respectively. Visualization of pulmonary lesions remained excellent in all cases. The radiation dose in case of SDCT was 2.7, and in case of LDCT - 0.67 mSv. The dose reduction was confirmed by dosimeter data. Similar results were obtained by repeating the experiment on a second scanner.

scholarly journals Evaluation of Algebraic Iterative Image Reconstruction Methods for Tetrahedron Beam Computed Tomography Systems

2013 ◽  
Vol 2013 ◽  
pp. 1-14
Author(s):  
Joshua Kim ◽  
Huaiqun Guan ◽  
David Gersten ◽  
Tiezhi Zhang
Keyword(s):  
Computed Tomography ◽  
Iterative Reconstruction ◽  
Cone Angle ◽  
Iterative Algorithms ◽  
Projection Data ◽  
Reconstruction Algorithms ◽  
Reconstruction Methods ◽  
Large Cone Angle ◽  
Using Data ◽  
Dual Detector

Tetrahedron beam computed tomography (TBCT) performs volumetric imaging using a stack of fan beams generated by a multiple pixel X-ray source. While the TBCT system was designed to overcome the scatter and detector issues faced by cone beam computed tomography (CBCT), it still suffers the same large cone angle artifacts as CBCT due to the use of approximate reconstruction algorithms. It has been shown that iterative reconstruction algorithms are better able to model irregular system geometries and that algebraic iterative algorithms in particular have been able to reduce cone artifacts appearing at large cone angles. In this paper, the SART algorithm is modified for the use with the different TBCT geometries and is tested using both simulated projection data and data acquired using the TBCT benchtop system. The modified SART reconstruction algorithms were able to mitigate the effects of using data generated at large cone angles and were also able to reconstruct CT images without the introduction of artifacts due to either the longitudinal or transverse truncation in the data sets. Algebraic iterative reconstruction can be especially useful for dual-source dual-detector TBCT, wherein the cone angle is the largest in the center of the field of view.

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