Impact of Operator-Selected Image Noise Index and Reconstruction Slice Thickness on Patient Radiation Dose in 64-MDCT

Kanal, Kalpana M.; Stewart, Brent K.; Kolokythas, Orpheus; Shuman, William P.

doi:10.2214/ajr.06.1524

Cited by 84 publications

(57 citation statements)

References 11 publications

(14 reference statements)

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“…Because the noise index varies with the section thickness, the predicted noise index for 2.5-mm section thickness was about 23.4 HU. 7 For each diagnostic scan, 80 mL of iohexol, 350 mg/mL (Omnipaque 350; GE Healthcare), was intravenously administered via a power injector (the initial 50 mL at a rate of 2 mL/s and the remaining 30 mL at 0.5 mL/s) followed by 30 mL of saline (0.9% NaCl) flush at a rate of 1.5 mL/s. The scan was acquired with a delay of 120 seconds following the commencement of contrast injection.…”

Section: Neck Ct Protocolmentioning

confidence: 99%

Impact of Model-Based Iterative Reconstruction on Image Quality of Contrast-Enhanced Neck CT

Gaddikeri

Andre

Benjert

et al. 2014

AJNR Am J Neuroradiol

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Section: Neck Ct Protocolmentioning

confidence: 99%

Impact of Model-Based Iterative Reconstruction on Image Quality of Contrast-Enhanced Neck CT

Gaddikeri

Andre

Benjert

et al. 2014

AJNR Am J Neuroradiol

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“…The way certain scan settings affect the ATCM from different vendors has been an area of interest for many years. 3,[5][6][7][8][9][10][11][12] The focus has been on the effect of a limited number of scan settings or on a specific vendor ATCM. However, an extensive study investigating the influence of all variable scan settings and covering all of the vendor implementations of ATCM is, to our knowledge, missing in the literature.…”

Section: Introductionmentioning

confidence: 99%

Evaluating the impact of scan settings on automatic tube current modulation in CT using a novel phantom

Merzan¹,

Nowik²,

Poludniowski³

et al. 2017

BJR

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Objective: The aim of this study was to make a comprehensive evaluation of how variable scan settings can affect the performance of automatic tube current modulation (ATCM) in recent CT scanners from the four major manufacturers. Methods: A phantom was designed and manufactured for the purpose of evaluating ATCM. The phantom was scanned with four categories of systematically varied settings (scan projection radiograph, technique and reconstruction parameters and phantom miscentring). The performance of ATCM, in terms of applied tube current and noise uniformity, for the scans with varied settings was compared with a reference scan using subjective and quantitative approaches. Results: The ATCM implemented by each manufacturer is based on different principles and any affect to the performance of the ATCM, when varying scan settings, will manifest differently among the vendors. The results are summarized in four tables corresponding to the categories of varied settings. Conclusion: The developed phantom proved useful for evaluating the ATCM. It is important to understand how different implementations (vendor specific) of ATCM perform in order to make informed decisions about the selection of scan settings when designing protocols. The resulting tables can serve as a reference for understanding the different implementations of ATCM and highlight settings that should be taken into consideration when adjusting an imaging protocol. Advances in knowledge:The results from this work can serve as a reference for how changes in geometry or scan settings can affect the performance of ATCM, in terms of tube current and noise.

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“…When selecting a noise index for a CT protocol, it is important to know the reconstructed section thickness at which the noise index is applied (13), since to maintain the same image noise (constant noise index), the radiation dose would have to be increased for the reconstruction of thin sections compared with thick sections. The degree of tube current modulation is calculated based on the noise index applied at the first prospectively reconstructed section thickness.…”

Section: Noise Index and Section Thicknessmentioning

confidence: 99%

“…For example, a study performed with a noise index of 15 and 5-mm-thick reconstructed images would have approximately the same radiation dose as a study performed with a noise index of 40 and 0.625-mm-thick reconstructed images. Appropriate selection of the noise index and the reconstructed section thickness at which the noise index is applied is essential for achieving optimal image quality with reduced dose when dose-modulated tube current is used (13). The tube current modulation does not depend on the choice of prospective section thickness when a reference image quality is used (14).…”

Section: Noise Index and Section Thicknessmentioning

confidence: 99%

“…The tube current is modulated based on the patient's attenuation profile as calculated from the scout image, to obtain images with constant noise closer to the prescribed noise index (13). Selecting a higher noise index allows more noise on resultant images; hence, a lower tube current is used, resulting in lower radiation dose.…”

Section: Atcm Based On Estimated Image Noisementioning

confidence: 99%

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Emerging Techniques for Dose Optimization in Abdominal CT

Kaza¹,

Platt²,

Goodsitt

et al. 2014

RadioGraphics

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Recent advances in computed tomographic (CT) scanning technique such as automated tube current modulation (ATCM), optimized x-ray tube voltage, and better use of iterative image reconstruction have allowed maintenance of good CT image quality with reduced radiation dose. ATCM varies the tube current during scanning to account for differences in patient attenuation, ensuring a more homogeneous image quality, although selection of the appropriate image quality parameter is essential for achieving optimal dose reduction. Reducing the x-ray tube voltage is best suited for evaluating iodinated structures, since the effective energy of the x-ray beam will be closer to the k-edge of iodine, resulting in a higher attenuation for the iodine. The optimal kilovoltage for a CT study should be chosen on the basis of imaging task and patient habitus. The aim of iterative image reconstruction is to identify factors that contribute to noise on CT images with use of statistical models of noise (statistical iterative reconstruction) and selective removal of noise to improve image quality. The degree of noise suppression achieved with statistical iterative reconstruction can be customized to minimize the effect of altered image quality on CT images. Unlike with statistical iterative reconstruction, model-based iterative reconstruction algorithms model both the statistical noise and the physical acquisition process, allowing CT to be performed with further reduction in radiation dose without an increase in image noise or loss of spatial resolution. Understanding these recently developed scanning techniques is essential for optimization of imaging protocols designed to achieve the desired image quality with a reduced dose.

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Impact of Operator-Selected Image Noise Index and Reconstruction Slice Thickness on Patient Radiation Dose in 64-MDCT

Abstract: This table and graph may help operators understand the trade-offs when prospectively trying to minimize dose and optimize image noise for selected reconstruction slice thicknesses on this type of 64-MDCT scanner.

Cited by 84 publications

References 11 publications

Impact of Model-Based Iterative Reconstruction on Image Quality of Contrast-Enhanced Neck CT

Impact of Model-Based Iterative Reconstruction on Image Quality of Contrast-Enhanced Neck CT

Evaluating the impact of scan settings on automatic tube current modulation in CT using a novel phantom

Emerging Techniques for Dose Optimization in Abdominal CT

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