Progress in the development of a dedicated breast CT scanner

Kwan, Alexander L. C.; Shah, Nikula; Burkett, George W.; Seibert, J. Anthony; Lindfors, Karen K.; Nelson, Thomas R.; Boone, John M.

doi:10.1117/12.537029

Cited by 7 publications

(8 citation statements)

References 9 publications

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“…The prototype cone-beam breast CT scanner was designed and fabricated in our laboratory using a number of "off-theshelf" components, 30 including an industrial tungsten target x-ray tube with a 0.4 mm focal spot ͑Comet AG, Flamatt, Switzerland͒ and a 14 bit 40ϫ 30 cm CsI ͑cesium iodide͒ flat panel detector ͑PaxScan 4030CB, Varian Medical Systems, Salt Lake City, UT͒. The detector was operating in the 2 ϫ 2 binning low gain ͑4 pF͒ mode, 3 with a postbinned pixel size of 0.388 mm ͑postbinned matrix size of 1024ϫ 768 pixels͒.…”

Section: A Experimental Setupmentioning

confidence: 99%

“…Recent advances in flat-panel ͑and other imaging͒ detectors 1-6 and cone-beam reconstruction algorithms [7][8][9][10][11][12][13][14][15][16][17][18][19] have lead to the development of numerous applications based on cone-beam computed tomography ͑CT͒. [20][21][22][23][24][25][26][27][28] We 29,30 and others [31][32][33] have explored the possibility of utilizing a pendant-geometry cone-beam CT system as a potential imaging strategy for breast cancer screening and diagnosis.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the spatial resolution characteristics of a cone‐beam breast CT scanner

et al. 2006

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The purpose of this study was to examine the spatial resolution of a prototype pendant-geometry cone-beam breast computed tomography (CT) system. Modulation transfer functions (MTFs) of the reconstructed image in the coronal (x and y) plane were computed as a function of the cone angle, the radial distance from the axis of rotation, the size of the reconstruction matrix, the back-projection filter used, and the number of projections acquired for the reconstruction. The results show that the cone angle and size of the reconstruction matrix have minimal impact on the MTF, while the MTF degraded radially from the axis of rotation (from 0.76 at 2.6 mm from axis of rotation down to 0.37 at 76.9 mm from axis of rotation at f=0.5 mm(-1)). The Ramp reconstruction filter increases the MTF near the axis of rotation relative to the Shepp-Logan filter, while an increase in the number of projections from 500 to 1000 increased the MTF near the periphery of the reconstructed image. The MTF in the z direction (anterior-posterior direction) was also evaluated. The z-direction MTF values tend to be higher when compared to the coronal MTF (0.85 at f =0.5 mm(-1)), and tend to be very constant throughout the coronal plane direction. The results suggest that an increase in the MTF for the prototype breast CT system is possible by optimizing various scanning and reconstruction parameters.

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Section: A Experimental Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of the spatial resolution characteristics of a cone‐beam breast CT scanner

et al. 2006

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“…Due to the object size, composition and geometry differences from previous studies and to confirm some of the theoretical results, scattered radiation levels were evaluated using the SPR for the dedicated cone-beam breast CT scanner designed and fabricated in our laboratory. 34 The SPR along the horizontal plane of the detector was measured and trends were characterized over a range of parameters relevant to breast CT imaging. These included x-ray beam energy, breast diameter, breast composition, isocenter-to-detector distance ͑air gap͒, collimated slot thickness, and grid ratio.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of x‐ray scatter properties in a dedicated cone‐beam breast CT scanner

2005

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The magnitude of scatter contamination on a first-generation prototype breast computed tomography (CT) scanner was evaluated using the scatter-to-primary ratio (SPR) metric. The SPR was measured and characterized over a wide range of parameters relevant to breast CT imaging, including x-ray beam energy, breast diameter, breast composition, isocenter-to-detector distance, collimated slot thickness, and grid ratio. The results demonstrated that in the absence of scatter reduction techniques, the SPR levels for the average breast (e.g., 14 cm diameter 50/50 composition cylindrical phantom) are quite high (approximately 0.5 at the center of the phantom for 80 kVp in true cone-beam CT geometry), and increases as the diameter of the phantom is increased (to approximately 1.0 at the center of a 18 cm diameter 50/50 phantom). The x-ray beam energy and the phantom compositions had only minimal impact on the measured SPR. When an ideal bowtie filter was used, the SPRs at the central axis of the 14 and 18 cm cylindrical phantoms were reduced while the SPRs at the edge of the phantoms were increased. Lastly, collimation in the vertical direction had a significant impact on the SPRs at the central axis of the phantoms. These high SPR levels might lead to cupping artifacts and increased noise in the reconstructed CT images, and this suggests that efficient scatter rejection and/or correction techniques may be required to improve the quality and accuracy of cone beam CT images.

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“…Following the same design as previously reported, [11][12][13] a pendant-geometry, cone-beam breast CT scanner was designed and fabricated in our laboratory.…”

Section: A System Setupmentioning

confidence: 99%

Evolution of spatial resolution in breast CT at UC Davis

et al. 2015

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Purpose: Dedicated breast computed tomography (bCT) technology for the purpose of breast cancer screening has been a focus of research at UC Davis since the late 1990s. Previous studies have shown that improvement in spatial resolution characteristics of this modality correlates with greater microcalcification detection, a factor considered a potential limitation of bCT. The aim of this study is to improve spatial resolution as characterized by the modulation transfer function (MTF) via changes in the scanner hardware components and operational schema. Methods: Four prototypes of pendant-geometry, cone-beam breast CT scanners were designed and developed spanning three generations of design evolution. To improve the system MTF in each bCT generation, modifications were made to the imaging components (x-ray tube and flat-panel detector), system geometry (source-to-isocenter and detector distance), and image acquisition parameters (technique factors, number of projections, system synchronization scheme, and gantry rotational speed). Results: Characterization of different generations of bCT systems shows these modifications resulted in a 188% improvement of the limiting MTF properties from the first to second generation and an additional 110% from the second to third. The intrinsic resolution degradation in the azimuthal direction observed in the first generation was corrected by changing the acquisition from continuous to pulsed x-ray acquisition. Utilizing a high resolution detector in the third generation, along with modifications made in system geometry and scan protocol, resulted in a 125% improvement in limiting resolution. An additional 39% improvement was obtained by changing the detector binning mode from 2 × 2 to 1 × 1. Conclusions: These results underscore the advancement in spatial resolution characteristics of breast CT technology. The combined use of a pulsed x-ray system, higher resolution flat-panel detector and changing the scanner geometry and image acquisition logic resulted in a significant fourfold improvement in MTF. C 2015 American Association of Physicists in Medicine.

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Progress in the development of a dedicated breast CT scanner

Cited by 7 publications

References 9 publications

Evaluation of the spatial resolution characteristics of a cone‐beam breast CT scanner

Evaluation of the spatial resolution characteristics of a cone‐beam breast CT scanner

Evaluation of x‐ray scatter properties in a dedicated cone‐beam breast CT scanner

Evolution of spatial resolution in breast CT at UC Davis

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