Effect of dose on image quality in a detector‐based dual‐exposure, dual‐energy system for chest radiography

Purpose: To assess the image quality of subtracted soft tissue and bone images of a CsI‐detector‐based dual‐energy system for chest radiography at varying dose levels. Material and Methods: We evaluated a CsI‐detector‐based, dual‐exposure, dual‐energy prototype system; 126 patients were categorized into groups of small, medium, and large. Fixed values were applied for mAs and mA. The patients were randomized into two groups with intended higher and lower speed pairs of approximately 400/1000 (high and low energy shot) and 200/500, respectively. True speed equivalents were calculated retrospectively using the detector dose. Image quality was evaluated by two highly experienced radiologists in consensus applying a rating scale of 1 to 5 for quality indicators such as image noise, residual bone structures, motion artifacts, and others. Results: Significantly decreased noise and a significant improvement for display of bone details in the bone image were noted with the higher dose, whereas a significant increase in motion artifacts reduced image quality at the higher dose. Conclusion: Radiation dose did not significantly influence the perception of dual‐energy image quality. Dual‐energy subtraction, as described, has the potential to become a future routine application in chest radiography.

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Motion Artifact Reduction in Contrast-Enhanced Dual-Energy Mammography – A Multireader Study about the Effect of Nonrigid Registration as Motion Correction on Image Quality

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren ◽

10.1055/a-1388-7712 ◽

2021 ◽

Author(s):

Markus Sistermanns ◽

Bernd Kowall ◽

Mathias Hörnig ◽

Karsten Beiderwellen ◽

Detlev Uhlenbrock

Keyword(s):

Image Quality ◽

Motion Correction ◽

High Energy ◽

Dual Energy ◽

Motion Artifacts ◽

Nonrigid Registration ◽

Correction Algorithm ◽

Contrast Enhanced ◽

The Mean

Purpose The technically caused delay between low-energy (LE) and high-energy (HE) acquisitions allows motion artifacts in contrast-enhanced dual-energy mammography (CEDEM). In this study the effect of motion correction by nonrigid registration on image quality of the recombined images was investigated. Materials and Methods Retrospectively for 354 recombined CEDEM images an additional recombined image was processed from the raw data of LE and HE images using the motion correction algorithm. Five radiologists with many years of experience in breast cancer diagnostic imaging compared side-by-side one conventional processed CEDEM image with the corresponding image processed by the motion correction algorithm. Every pair of images was compared based on six criteria: General image quality (1), sharpness of skin contour (2), reduction of image artifacts (3), sharpness of lesion contour (4), contrast of lesion (5), visibility of lymph nodes (6). These criteria were rated on a Likert scale (improvement: + 1, + 2; deterioration: –1, –2). Results The mean ratings concerning criteria 1–5 showed a superiority of the recombined images processed by the motion correction algorithm. For example, the mean rating of general image quality was 0.86 (95 % CI: 0.78; 0.93). Only the mean rating concerning criterion 6 showed an inferiority of the recombined images processed by the motion correction algorithm (–0.29 (–0.46; –0.13)). Conclusion The usage of nonrigid registration for motion correction significantly improves the general image quality and the quality of subordinate criteria on the recombined CEDEM images at the expense of somewhat reduced lymph node visibility in some cases. Key Points: Citation Format

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Comparison of dose and image quality of dual-energy CT pulmonary angiografy on 2nd and 3 rd generation dual-source scanners

RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren ◽

10.1055/s-0035-1550807 ◽

2015 ◽

Vol 187 (S 01) ◽

Author(s):

S Fischer ◽

N Schultheis ◽

P Dewes ◽

J Scholtz ◽

M Kerl ◽

...

Keyword(s):

Image Quality ◽

Dual Energy ◽

Dual Energy Ct ◽

Dual Source

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Metal artefact reduction of different alloys with dual energy computed tomography (DECT)

Scientific Reports ◽

10.1038/s41598-021-81600-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Anand John Vellarackal ◽

Achim Hermann Kaim

Keyword(s):

Stainless Steel ◽

Image Quality ◽

Femoral Stem ◽

Dual Energy ◽

Dual Energy Ct ◽

Bony Tissue ◽

Stem Image ◽

Metal Artefact ◽

Artefact Reduction

AbstractTo evaluate the influence of dual-energy CT (DECT) and Virtual monochromatic spectral (VMS) imaging on: (1) the artefact size of geometrically identical orthopaedic implants consisting of three different compositions and (2) the image quality of the surrounding bone, three similar phantoms—each featuring one femoral stem composed of either titanium, chrome-cobalt or stainless steel surrounded by five calcium pellets (200 mg hydroxyapatite/calcium carbonate) to simulate bony tissue and one reference pellet located away from the femoral stem—were built. DECT with two sequential scans (80 kVp and 140 kVp; scan-to-scan technique) was performed, and VMS images were calculated between 40 and 190 keV. The artefact sizes were measured volumetrically by semiautomatic selection of regions of interest (ROIs), considering the VMS energies and the polychromatic spectres. Moreover, density and image noise within the pellets were measured. All three phantoms exhibit artefact size reduction as energy increases from 40 to 190 keV. Titanium exhibited a stronger reduction than chrome-cobalt and stainless steel. The artefacts were dependent on the diameter of the stem. Image quality increases with higher energies on VMS with a better depiction of surrounding structures. Monoenergetic energies 70 keV and 140 keV demonstrate superior image quality to those produced by spectral energies 80 kVp and 140 kVp.

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