Advanced single‐slice rebinning in cone‐beam spiral CT

Kachelrieß, Marc; Schaller, Stefan; Kalender, Willi A.

doi:10.1118/1.598938

Cited by 153 publications

(130 citation statements)

References 12 publications

(17 reference statements)

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“…When the detector extent in the z-direction is increased, the cone angle, κ, increases just the same from 0°to typically 5-20°. For clinical CT, it has been shown that up to 64 slices, corresponding to about 2-4°cone angle, approximate reconstruction approaches such as the so-called advanced single-slice rebinning (ASSR) algorithms applied to spiral CT scan data provide excellent image quality [23]. For wider cone angles and for circular scan trajectories the situation is complicated.…”

Section: Technology Of C-arm Fd-ct Systemsmentioning

confidence: 99%

Flat-detector computed tomography (FD-CT)

2007

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Flat-panel detectors or, synonymously, flat detectors (FDs) have been developed for use in radiography and fluoroscopy with the defined goal to replace standard X-ray film, filmscreen combinations and image intensifiers by an advanced sensor system. FD technology in comparison to X-ray film and image intensifiers offers higher dynamic range, dose reduction, fast digital readout and the possibility for dynamic acquisitions of image series, yet keeping to a compact design. It appeared logical to employ FD designs also for computed tomography (CT) imaging. Respective efforts date back a few years only, but FD-CT has meanwhile become widely accepted for interventional and intraoperative imaging using C-arm systems. FD-CT provides a very efficient way of combining two-dimensional (2D) radiographic or fluoroscopic and 3D CT imaging. In addition, FD technology made its way into a number of dedicated CT scanner developments, such as scanners for the maxillo-facial region or for micro-CT applications. This review focuses on technical and performance issues of FD technology and its full range of applications for CT imaging. A comparison with standard clinical CT is of primary interest. It reveals that FD-CT provides higher spatial resolution, but encompasses a number of disadvantages, such as lower dose efficiency, smaller field of view and lower temporal resolution. FD-CT is not aimed at challenging standard clinical CT as regards to the typical diagnostic examinations; but it has already proven unique for a number of dedicated CT applications, offering distinct practical advantages, above all the availability of immediate CT imaging in the interventional suite or the operating room.

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Section: Technology Of C-arm Fd-ct Systemsmentioning

confidence: 99%

Flat-detector computed tomography (FD-CT)

2007

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“…For small cone-angles fan beam formulas may be applied directly to interpolated helical data (32)(33)(34)(35). For the moderate cone-angles of current state-of-the-art 64-slice scanners, FDK-type approximations that utilize heuristic filtering and exact 3D backprojection may be employed (17,(36)(37)(38).…”

Section: Discussionmentioning

confidence: 99%

Temporally Targeted Imaging Method Applied to ECG-Gated Computed Tomography

Nett¹,

Leng²,

Zambelli³

et al. 2008

Academic Radiology

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Rationale and Objectives-Existing cardiac imaging methods do not allow for improved temporal resolution when considering a targeted region of interest (ROI). The imaging method presented here enables improved temporal resolution for ROI imaging (namely, a reconstruction volume smaller than the complete field of view). Clinically, temporally targeted reconstruction would not change the primary means of reconstructing and evaluating images, but rather would enable the adjunct technique of ROI imaging, with improved temporal resolution compared with standard reconstruction (~20% smaller temporal scan window). In gated cardiac CT scans improved temporal resolution directly translates into a reduction in motion artifacts for rapidly moving objects such as the coronary arteries.Materials and Methods-Retrospectively electrocardiogram gated coronary angiography data from a 64-slice CT system were utilized. A motion phantom simulating the motion profile of a coronary artery was constructed and scanned. Additionally, an in vivo study was performed using a porcine model. Comparisons between the new reconstruction technique and the standard reconstruction are given for an ROI centered on the right coronary artery, and a pulmonary ROI.Results-In both a well controlled motion model and a porcine model results show a decrease in motion induced artifacts including motion blur and streak artifacts from contrast enhanced vessels within the targeted ROIs, as assessed through both qualitative and quantitative observations. Conclusion-Temporally targeted reconstruction techniques demonstrate the potential to reduce motion artifacts in coronary CT. Further study is warranted to demonstrate the conditions under which this technique will offer direct clinical utility. Improvement in temporal resolution for gated cardiac scans has implications for improving: contrast enhanced CT angiography, calcium scoring, and assessment of the pulmonary anatomy.

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“…For helical cone-beam CT, several rebinning methods have been developed. [47][48][49][50][51] Among them, the Advanced SingleSlice Rebinning (ASSR) method 49 is an effective algorithm which uses virtual tilted reconstruction planes along a helical path to Z-interpolate the images onto a Cartesian grid. The key step in ASSR is to rebin the helical cone-beam data into a series of 2D projections along virtual tilted planes that can be reconstructed by using conventional 2D FBP.…”

Section: Iiie Extending Est To Helical Cone-beam Ctmentioning

confidence: 99%

Radiation dose reduction in medical x‐ray CT via Fourier‐based iterative reconstruction

et al. 2013

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Purpose: A Fourier-based iterative reconstruction technique, termed Equally Sloped Tomography (EST), is developed in conjunction with advanced mathematical regularization to investigate radiation dose reduction in x-ray CT. The method is experimentally implemented on fan-beam CT and evaluated as a function of imaging dose on a series of image quality phantoms and anonymous pediatric patient data sets. Numerical simulation experiments are also performed to explore the extension of EST to helical cone-beam geometry. Methods: EST is a Fourier based iterative algorithm, which iterates back and forth between real and Fourier space utilizing the algebraically exact pseudopolar fast Fourier transform (PPFFT). In each iteration, physical constraints and mathematical regularization are applied in real space, while the measured data are enforced in Fourier space. The algorithm is automatically terminated when a proposed termination criterion is met. Experimentally, fan-beam projections were acquired by the Siemens z-flying focal spot technology, and subsequently interleaved and rebinned to a pseudopolar grid. Image quality phantoms were scanned at systematically varied mAs settings, reconstructed by EST and conventional reconstruction methods such as filtered back projection (FBP), and quantified using metrics including resolution, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs). Pediatric data sets were reconstructed at their original acquisition settings and additionally simulated to lower dose settings for comparison and evaluation of the potential for radiation dose reduction. Numerical experiments were conducted to quantify EST and other iterative methods in terms of image quality and computation time. The extension of EST to helical cone-beam CT was implemented by using the advanced single-slice rebinning (ASSR) method. helical cone-beam CT data suggest that the combination of EST and ASSR produces reconstructions with higher image quality and lower noise than the Feldkamp Davis and Kress (FDK) method and the conventional ASSR approach. Conclusions: A Fourier-based iterative method has been applied to the reconstruction of fan-bean CT data with reduced x-ray fluence. This method incorporates advantageous features in both real and Fourier space iterative schemes: using a fast and algebraically exact method to calculate forward projection, enforcing the measured data in Fourier space, and applying physical constraints and flexible regularization in real space. Our results suggest that EST can be utilized for radiation dose reduction in x-ray CT via the readily implementable technique of lowering mAs settings. Numerical experiments further indicate that EST requires less computation time than several other iterative algorithms and can, in principle, be extended to helical cone-beam geometry in combination with the ASSR method.

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Advanced single‐slice rebinning in cone‐beam spiral CT

Cited by 153 publications

References 12 publications

Flat-detector computed tomography (FD-CT)

Flat-detector computed tomography (FD-CT)

Temporally Targeted Imaging Method Applied to ECG-Gated Computed Tomography

Radiation dose reduction in medical x‐ray CT via Fourier‐based iterative reconstruction

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