Artefacts and remedies in direct Fourier tomographic reconstruction

Magnusson, Maria; Danielsson, Per-Erik; Edholm, Paul

doi:10.1109/nssmic.1992.301056

Cited by 25 publications

(29 citation statements)

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“…For each detector, three data sets with a pitch corresponding to the 1-PI-, 3-PI-, and 5-PI-window were calculated. Reconstruction was performed using a bandlimited ramp filter [30].…”

Section: B Simulation Resultsmentioning

confidence: 99%

“…Each row is treated the same way. The new projection angle and the new column coordinate are related to the vertex position and the fan-angle according to (30) This leads to the geometry shown in Fig. 7.…”

Section: The -Pi-fbp-methodsmentioning

confidence: 99%

“…23. As the triangle spanned by , the rotation axis, and is isosceles, the -position of the intersection of the ray with the virtual detector is (46) (47) (48) where denotes the projection angle of the virtual detector (30). Therefore, all rays contributing to the projection angle that hit the upper boundary of the physical detector, intersect the virtual detector at , which is then a rectangle.…”

Section: B Proof That the Rebinned Detector Is Rectangularmentioning

confidence: 99%

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The n-PI-method for helical cone-beam CT

Proksa

Köhler²,

Graß³

et al. 2000

IEEE Trans. Med. Imaging

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Abstract-A new class of acquisition schemes for helical cone-beam computed tomography (CB-CT) scanning is introduced, and their effect on the reconstruction methods is analyzed. These acquisition schemes are based on a new detector shape that is bounded by the helix. It will be shown that the data acquired with these schemes are compatible with exact reconstruction methods, and the adaptation of exact reconstruction algorithms to the new acquisition geometry is described. At the same time, the so-called PI-sufficiency condition is fulfilled. Moreover, a good fit to the acquisition requirements of the various medical applications of cone-beam CT is achieved. In contrast to other helical cone-beam acquisition and reconstruction methods, the -PI-method introduced in this publication allows for variable pitches of the acquisition helix. This additional feature will introduce a higher flexibility into the acquisition protocols of future medical cone-beam scanners. An approximative -PI-filtered backprojection ( -PI-FBP) reconstruction method is presented and verified. It yields convincing image quality.Index Terms-Exact reconstruction, helical cone-beam computed tomography, PI-method, Radon-inversion.

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“…For each detector, three data sets with a pitch corresponding to the 1-PI-, 3-PI-, and 5-PI-window were calculated. Reconstruction was performed using a bandlimited ramp filter [30].…”

Section: B Simulation Resultsmentioning

confidence: 99%

Section: The -Pi-fbp-methodsmentioning

confidence: 99%

Section: B Proof That the Rebinned Detector Is Rectangularmentioning

confidence: 99%

See 1 more Smart Citation

The n-PI-method for helical cone-beam CT

Proksa

Köhler²,

Graß³

et al. 2000

IEEE Trans. Med. Imaging

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“…1, a set of projections (density function) g(θ i, ρ) is obtained from each object slice for all rotation angles θ i . A projection consists of a collection of line integrals of the object attenuation coefficients µ(x , y) corresponding to the various rays coming from the source [5].…”

Section: Methodsmentioning

confidence: 99%

“…To compute the inverse Fourier transform (using a FFT algorithm) we must determine the values on a square grid In spite of the potential speed advantage of the DF Method as compared to the FB Method, it has not been used in practice because of its inferior image quality. There are two main sources of artifacts: the interpolation procedure and the circular convolution (inherent ramp filtering) [5].…”

Section: The Reconstruction Toolmentioning

confidence: 99%

Tomography simulation and reconstruction tools applied in the evaluation of parameters and techniques

Azevedo

Helegda

Godoy

et al.

2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society

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-In this paper we introduce a tomography platform consisting of a new set of programs written in ANSI C++ to help researchers to develop and to evaluate tomography simulation/reconstruction based on the Direct Fourier Method. We applied these tools in the evaluation of tomographic techniques. We describe and compare two techniques to overcome the inferior image quality due to the inherent artifacts of the Direct Fourier Method: the increase of the zero-padding factor and the resampling grid density factor.

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