방사선의학 웹진

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Abstract
Background: Chest radiography is a widely used medical imaging modality for diagnosing chest-related diseases. However, anatomical structure overlap hinders accurate lesion detection. While the dual-energy x-ray imaging technique addresses this issue by separating soft-tissue and bone images from an original chest radiograph, scattered radiation remains a significant challenge in decomposition image quality.

Purpose: This work aims to conduct dual-energy material decomposition (DEMD) in chest radiography using a two-dimensional (2D) crisscrossed anti-scatter grid to improve decomposition image quality by effectively removing scattered radiation.

Methods: A 2D graphite-interspaced grid with a strip density of N = 1.724 lines/mm and grid ratio r = 6:1 was fabricated using a high-precision sawing process. The grid characteristics were evaluated using the IEC standard fixture. A 2D-grid-based DEMD process, which involves the acquisition of low- and high-kV radiographs with a 2D grid, generation of a pairwise decomposition function using a calibration wedge phantom, and decomposition of soft-tissue and bone images using the decomposition function, was implemented, followed by software-based grid artifact reduction. Experiments were conducted on a commercially available chest phantom using an x-ray imaging system operating at two tube voltages of 70 and 120 kVp. The decomposition image quality of the proposed DEMD and conventional dual-energy subtraction methods was compared for the cases of no grid, software-based scatter correction, 1D grid (N = 8.475 lines/mm and r = 12:1), and 2D grid.

Results: The 2D grid demonstrated superior scatter radiation removal ability with scatter radiation transmission of 6.34% and grid selectivity of 9.67, representing a 2.6-fold decrease and a 2.7-fold improvement over the 1D grid, respectively. Compared to other competitive methods, the 2D-grid-based DEMD method considerably improved decomposition image quality, with improved lung structure visibility in selective soft-tissue images.

Conclusions: The proposed DEMD method yielded high-quality dual-energy chest radiographs by effectively removing scattered radiation, demonstrating significant potential for improving lesion detection in clinical practice.

Affiliations

Duhee Jeon 1, Younghwan Lim 1, Hyesun Yang 1, Myeongkyu Park 2, Kyong-Woo Kim 2, Hyosung Cho 1
1Department of Radiation Convergence Engineering, Yonsei University, Wonju, Republic of Korea.
2R&D Center, JPI Healthcare Co., Ltd., Seoul, Republic of Korea.