The Effects Of Iterative Reconstruction Algorithms On The Measurement Of Emphysema Using Low Radiation Dose Computed Tomography Scans

2011 ◽  
Author(s):  
Natasha M. Krowchuk ◽  
Cameron Hague ◽  
Jonathon Leipsic ◽  
John R. Mayo ◽  
Don Sin ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
Iterative Reconstruction ◽  
Reconstruction Algorithms ◽  
Low Radiation Dose ◽  
Computed Tomography Scans

Image quality in coronary computed tomography angiography: influence of adaptive statistical iterative reconstruction at various radiation dose levels

2018 ◽  
Vol 59 (10) ◽  
pp. 1194-1202 ◽  
Author(s):  
Helle Precht ◽  
Oke Gerke ◽  
Jesper Thygesen ◽  
Kenneth Egstrup ◽  
Søren Auscher ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Radiation Dose ◽  
Iterative Reconstruction ◽  
Quality Criteria ◽  
Left Ventricular ◽  
Reconstruction Algorithms ◽  
Adaptive Statistical Iterative Reconstruction ◽  
Low Contrast ◽  
Statistical Iterative Reconstruction

Background Computed tomography (CT) technology is rapidly evolving and software solution developed to optimize image quality and/or lower radiation dose. Purpose To investigate the influence of adaptive statistical iterative reconstruction (ASIR) at different radiation doses in coronary CT angiography (CCTA) in detailed image quality. Material and Methods A total of 160 CCTA were reconstructed as follows: 55 scans with filtered back projection (FBP) (650 mA), 51 scans (455 mA) with 30% ASIR (ASIR30), and 54 scans (295 mA) with 60% ASIR (ASIR60). For each reconstruction, subjective image quality was assessed by five independent certified cardiologists using a visual grading analysis (VGA) with five predefined image quality criteria consisting of a 5-point scale. Objective measures were contrast, noise, and contrast-to-noise ratio (CNR). Results The CTDIvol resulted in 10.3 mGy, 7.4 mGy, and 4.6 mGy for FBP, ASIR30, and ASIR60, respectively. Homogeneity of the left ventricular lumen was the sole aspect in which reconstruction algorithms differed with a decreasing effect for ASIR60 compared to FBP (estimated odds ratio [OR] = 0.49 [95% confidence interval (CI) = 0.32–0.76; P = 0.001]). Decreased sharpness and spatial- and low-contrast resolutions were observed when using ASIR instead of FBP, but differences were not statistically significant. Concerning objective measurements, noise increased significantly for ASIR30 (OR = 1.08; 95% CI = 1.02–1.14; P = 0.006) and ASIR60 (OR = 1.06; 95% CI = 1.01–1.12; P = 0.034) compared to FBP. Conclusion ASIR significantly decreased the subjectively assessed homogeneity of the left ventricular lumen and increased the objectively measured noise compared to FBP. Considering these results, ASIR at a reduced radiation dose should be implemented with caution.

Model-based Iterative Reconstruction in Low-radiation-dose Computed Tomography Colonography

2018 ◽  
Vol 25 (4) ◽  
pp. 415-422 ◽  
Author(s):  
Narumi Taguchi ◽  
Seitaro Oda ◽  
Masanori Imuta ◽  
Sadahiro Yamamura ◽  
Takeshi Nakaura ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
Iterative Reconstruction ◽  
Low Radiation Dose ◽  
Computed Tomography Colonography ◽  
Model Based

scholarly journals Low Radiation Dose Implications in Obese Abdominal Computed Tomography Imaging

2021 ◽  
Vol 11 (6) ◽  
pp. 2456
Author(s):  
Abdulaziz A. Qurashi ◽  
Louise A. Rainford ◽  
Fahad H. Alhazmi ◽  
Khalid M. Alshamrani ◽  
Abdelmoneim Sulieman ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
Noise Reduction ◽  
Effective Dose ◽  
Iterative Reconstruction ◽  
Multidetector Ct ◽  
Obese Patients ◽  
Organ Doses ◽  
Low Radiation Dose ◽  
Abdominal Computed Tomography

The aim of this study was to evaluate the implications of low radiation dose in abdominal computed tomography (CT) when combined with noise reduction filters and to see if this approach can overcome the challenges that arise while scanning obese patients. Anthropomorphic phantoms layered with and without 3-cm-thick circumferential animal fat packs to simulate different sized patients were scanned using a 128-slice multidetector CT (MDCT) scanner. Abdominal protocols (n = 12) were applied using various tube currents (150, 200, 250, and 300 mA) and tube voltages (100, 120, and 140 kVp). MOSFET dosimeters measured the internal organ dose. All images were reconstructed with filtered back projection (FBP) and different iterative reconstruction (IR) strengths (SAFIRE 3, SAFIRE 4, and SAFIRE 5) techniques and objective noise was measured within three regions of interests (ROIs) at the level of L4–L5. Organ doses varied from 0.34–56.2 mGy; the colon received the highest doses for both phantom sizes. Compared to the normal-weighted phantom, the obese phantom was associated with an approximately 20% decrease in effective dose. The 100 kVp procedure resulted in a 40% lower effective dose (p < 0.05) compared to at 120 kVp and the associated noise increase was improved by increasing the IR (5) use, which resulted in a 60% noise reduction compared to when using FBP (p < 0.05). When combined with iterative reconstruction, the low-kVp approach is feasible for obese patients in order to optimize radiation dose and maintain objective image quality.

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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