Characterization, detection, and supression of stationary grids in digital projection radiography imagery

Barski, Lori L.; Wang, Xiaohui

doi:10.1117/12.349462

Cited by 21 publications

(14 citation statements)

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“…Even though we use the moving grids, the grid artifact is still visible as shown in Fig. 1(a), and thus it should be removed from the obtained x-ray image by applying filters in the spatial [1] or frequency domain [2]. In the frequency domain, the grid artifacts can be described as amplitude-modulated terms [3], and thus the band-rejection filters (BRFs) should be applied to remove the grid artifacts.…”

Section: Introductionmentioning

confidence: 98%

Slope detector for determination of the ringing artifact in filtering x-ray images

Kim

Lee²

2012

2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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In order to reduce the grid artifacts, which are caused by using the antiscatter grid in obtaining x-ray digital images, we analyze the effect of applying band-rejection filters (BRFs) in the frequency domain. The property of the grid artifacts is quite different depending on the shape of the object to be recovered in the spatial domain. Furthermore, if the frequency component of the grid artifact is relatively close to that of the object, then simply applying a BRF may seriously distort the object and cause the ringing artifact. In this paper, we propose a hybrid filtering scheme, which can cooperate such different properties in the spatial domain. In order to perform a robust detection of the position of the ringing artifact, we propose the frequency-modulation (FM) model for the extracted signal, which corresponds to a specific grid artifact. An estimation of the position image for the ringing artifact is then conducted based on the slope detection algorithm, which is commonly used as an FM discriminator in the communication area. Numerical result for real x-ray images shows that applying BRFs in the frequency domain in conjunction with the spatial property of the ringing artifact can successfully remove the grid artifact, distorting the object less.

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Section: Introductionmentioning

confidence: 98%

Slope detector for determination of the ringing artifact in filtering x-ray images

Kim

Lee²

2012

2012 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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“…3 The objective of the study was to minimize the aliasing artifacts while converting a film into digital form. In another study by Barski and Wang,4 a method consisting of grid frequency detection and adaptive grid suppression was proposed. The grid artifact frequency was detected in the frequency domain after a 1-dimensional Fourier transform.…”

Section: Introductionmentioning

confidence: 99%

A Study of Grid Artifacts Formation and Elimination in Computed Radiographic Images

Lin¹,

Lee

Chen

et al. 2006

J Digit Imaging

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Computed radiography (CR) has many advantages such as filmless operations, efficiency, and convenience. Furthermore, it is easier to integrate with the picture archiving and communication systems. Another important advantage is that CR images generally have a wider dynamic range than conventional screen film. Unfortunately, grid artifacts and moiré pattern artifacts may be present in CR images. These artifacts become a more serious problem when viewing CR images on a computer monitor when a clinic grade monitor is not available. Images produced using a grid with higher frequency or a Potter--Bucky grid (i.e., a moving grid, Bucky for short) can reduce occurrence but cannot guarantee elimination of these artifacts [CR & PACS (2000); Detrick F (2001), pp 7-8]. In this paper, the formation of the artifacts is studied. We show that the grid artifacts occur in a narrow band of frequency in the frequency domain. The frequency can be determined, accurately located, and thus removed from the frequency domain. When comparing the results obtained from the proposed method against the results obtained using previous computer methods, we show that our method can achieve better image quality.

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“…However, simply rotating the grid is not enough to remove the grid artifacts for flat panel digital detectors. Furthermore, most current algorithms 7,19,20,22 are focused on the reduction of weak or blurred grid artifacts, which are produced by the CR or the indirect detectors, and thus cannot effectively remove even the fundamental component of the grid artifact near sharp edges within the image for the direct image detector case. (Note that, in a digital radiography system with poor resolution, the grid pattern is blurred or even becomes invisible.…”

Section: Introductionmentioning

confidence: 99%

“…By employing BSF in the frequency domain, we can considerably suppress the grid artifact comparing to the nonrotated grid and linear filtering case of Lin et al 7 and Sasada et al, 21 even for strong grid artifacts from the direct image detector. Furthermore, for specific grid frequencies and angles, we use a simple 1D LPF in the spatial domain and compare the performance with similar spatial-domain filtering approaches of Barski and Wang 19 and Belykh and Cornelius. 20 The proposed algorithm can further suppress the grid artifacts and maintain the object sharpness compared to the previous approaches, and can be implemented with very low implementation complexity since the discrete Fourier transform and any estimating scheme for artifact frequencies are not used.…”

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confidence: 99%

Grid artifact reduction for direct digital radiography detectors based on rotated stationary grids with homomorphic filtering

Kim

Lee²

2013

Medical Physics

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By employing the homomorphic filtering technique, the authors can considerably suppress the strong grid artifacts with relatively narrow-bandwidth filters compared to the normal filtering case. Using rotated grids also significantly reduces the ringing artifact. Furthermore, for specific grid frequencies and angles, the authors can use simple homomorphic low-pass filters in the spatial domain, and thus alleviate the grid artifacts with very low implementation complexity.

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Characterization, detection, and supression of stationary grids in digital projection radiography imagery

Cited by 21 publications

References 0 publications

Slope detector for determination of the ringing artifact in filtering x-ray images

Slope detector for determination of the ringing artifact in filtering x-ray images

A Study of Grid Artifacts Formation and Elimination in Computed Radiographic Images

Grid artifact reduction for direct digital radiography detectors based on rotated stationary grids with homomorphic filtering

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