Temporal Bone CT: Improved Image Quality and Potential for Decreased Radiation Dose Using an Ultra-High-Resolution Scan Mode with an Iterative Reconstruction Algorithm

Leng, Shuai; Diehn, Felix E.; Lane, John I.; Koeller, Kelly K.; Witte, Robert J.; Carter, R.E.; McCollough, Cynthia H.

doi:10.3174/ajnr.a4338

Cited by 43 publications

(22 citation statements)

References 19 publications

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“…This results in reduced dose efficiency and consequently higher noise (for the same dose) for exams using the comb filters. 3,8 The PCD UHR mode investigated in this study does not have this issue, as no comb filters are used and all photons reaching the detector are used in image formation without losing dose efficiency. Our results demonstrated a 50% improvement in dose efficiency using the PCD UHR mode with matched image noise to that of EID, which would substantially reduce the necessary radiation dose for exams requiring these levels of spatial resolution.…”

Section: Discussionmentioning

confidence: 99%

“…[3][4][5][6] One approach for improving spatial resolution is to use comb or grid attenuators in front of the detectors to reduce the effective detector aperture. 3,7,8 This approach, however, comes with a reduction of dose efficiency as the comb or grid attenuates photons that have already passed through the patient and would otherwise have contributed to the image formation. Another approach that has been investigated on a prototype system is to use a flat-panel detector to provide spatial resolution as fine as 150 μm.…”

Section: Introductionmentioning

confidence: 99%

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Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

et al. 2016

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, "Dose-efficient ultrahighresolution scan mode using a photon counting detector computed tomography system," J. Med. Imag. 3(4), 043504 (2016), doi: 10.1117/1.JMI.3.4.043504. Abstract. An ultrahigh-resolution (UHR) data collection mode was enabled on a whole-body, research photon counting detector (PCD) computed tomography system. In this mode, 64 rows of 0.45 mm × 0.45 mm detector pixels were used, which corresponded to a pixel size of 0.25 mm × 0.25 mm at the isocenter. Spatial resolution and image noise were quantitatively assessed for the UHR PCD scan mode, as well as for a commercially available UHR scan mode that uses an energy-integrating detector (EID) and a set of comb filters to decrease the effective detector size. Images of an anthropomorphic lung phantom, cadaveric swine lung, swine heart specimen, and cadaveric human temporal bone were qualitatively assessed. Nearly equivalent spatial resolution was demonstrated by the modulation transfer function measurements: 15.3 and 20.3 lp∕cm spatial frequencies were achieved at 10% and 2% modulation, respectively, for the PCD system and 14.2 and 18.6 lp∕cm for the EID system. Noise was 29% lower in the PCD UHR images compared to the EID UHR images, representing a potential dose savings of 50% for equivalent image noise. PCD UHR images from the anthropomorphic phantom and cadaveric specimens showed clear delineation of small structures.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

et al. 2016

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“…a CT scanner or 3D laser scanner; the imaging modality must provide high resolution and fidelity to avoid compounding errors. In this study, we used an ultra-high resolution mode of a commercial CT system having an resolution of 0.2 mm in plane and 0.4 mm off plane [ 29 – 31 ]. A high radiation dose was used to eliminate the influence of image noise.…”

Section: Methodsmentioning

confidence: 99%

Anatomic modeling using 3D printing: quality assurance and optimization

Leng¹,

McGee²,

Morris³

et al. 2017

3D Print Med

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BackgroundThe purpose of this study is to provide a framework for the development of a quality assurance (QA) program for use in medical 3D printing applications. An interdisciplinary QA team was built with expertise from all aspects of 3D printing. A systematic QA approach was established to assess the accuracy and precision of each step during the 3D printing process, including: image data acquisition, segmentation and processing, and 3D printing and cleaning. Validation of printed models was performed by qualitative inspection and quantitative measurement. The latter was achieved by scanning the printed model with a high resolution CT scanner to obtain images of the printed model, which were registered to the original patient images and the distance between them was calculated on a point-by-point basis.ResultsA phantom-based QA process, with two QA phantoms, was also developed. The phantoms went through the same 3D printing process as that of the patient models to generate printed QA models. Physical measurement, fit tests, and image based measurements were performed to compare the printed 3D model to the original QA phantom, with its known size and shape, providing an end-to-end assessment of errors involved in the complete 3D printing process. Measured differences between the printed model and the original QA phantom ranged from -0.32 mm to 0.13 mm for the line pair pattern. For a radial-ulna patient model, the mean distance between the original data set and the scanned printed model was -0.12 mm (ranging from -0.57 to 0.34 mm), with a standard deviation of 0.17 mm.ConclusionsA comprehensive QA process from image acquisition to completed model has been developed. Such a program is essential to ensure the required accuracy of 3D printed models for medical applications.

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“…To address this limitation, state-of-the-art CT systems offer acquisition modes with enhanced spatial resolution for those specific clinical applications that may benefit from additional anatomical detail. Higher spatial resolution can be achieved on a conventional CT system by selectively covering part of each detector element with the use of comb or grid z-ray attenuators to reduce the effective detector aperture [3–5]. However, limiting the detector aperture is dose-inefficient, with only less of 25% of the x-rays contributing to the image formation when half the detector pixel area is covered in both directions, compared to a conventional acquisition mode.…”

Section: Introductionmentioning

confidence: 99%

Renal stone characterization using high resolution imaging mode on a photon counting detector CT system

Ferrero

Gutjahr

Henning

et al. 2017

Medical Imaging 2017: Physics of Medical Imaging

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In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm × 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same sub-elements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones -10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) -and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

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Temporal Bone CT: Improved Image Quality and Potential for Decreased Radiation Dose Using an Ultra-High-Resolution Scan Mode with an Iterative Reconstruction Algorithm

Cited by 43 publications

References 19 publications

Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

Anatomic modeling using 3D printing: quality assurance and optimization

Renal stone characterization using high resolution imaging mode on a photon counting detector CT system

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