Reducing Ionizing Radiation Dose during Ct-Guided Percutaneous Drainage of Pelvic Collections and Abscesses Using Iterative Reconstruction Algorithms: Preliminary Experience

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.

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Development of Limited-Angle Iterative Reconstruction Algorithms with Context Encoder-Based Sinogram Completion for Micro-CT Applications

Sensors ◽

10.3390/s18124458 ◽

2018 ◽

Vol 18 (12) ◽

pp. 4458 ◽

Cited By ~ 2

Author(s):

Shih-Chun Jin ◽

Chia-Jui Hsieh ◽

Jyh-Cheng Chen ◽

Shih-Huan Tu ◽

Ya-Chen Chen ◽

...

Keyword(s):

Image Quality ◽

Radiation Dose ◽

Iterative Reconstruction ◽

Micro Ct ◽

Reconstruction Algorithms ◽

Generative Adversarial Network ◽

Adversarial Network ◽

Novel Approach ◽

Ct System ◽

Limited Angle

Limited-angle iterative reconstruction (LAIR) reduces the radiation dose required for computed tomography (CT) imaging by decreasing the range of the projection angle. We developed an image-quality-based stopping-criteria method with a flexible and innovative instrument design that, when combined with LAIR, provides the image quality of a conventional CT system. This study describes the construction of different scan acquisition protocols for micro-CT system applications. Fully-sampled Feldkamp (FDK)-reconstructed images were used as references for comparison to assess the image quality produced by these tested protocols. The insufficient portions of a sinogram were inpainted by applying a context encoder (CE), a type of generative adversarial network, to the LAIR process. The context image was passed through an encoder to identify features that were connected to the decoder using a channel-wise fully-connected layer. Our results evidence the excellent performance of this novel approach. Even when we reduce the radiation dose by 1/4, the iterative-based LAIR improved the full-width half-maximum, contrast-to-noise and signal-to-noise ratios by 20% to 40% compared to a fully-sampled FDK-based reconstruction. Our data support that this CE-based sinogram completion method enhances the efficacy and efficiency of LAIR and that would allow feasibility of limited angle reconstruction.

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