Low-Kilovoltage, High-Tube-Current MDCT of Liver in Thin Adults: Pilot Study Evaluating Radiation Dose, Image Quality, and Display Settings

Nakaura, Takeshi; Awai, Kazuo; Oda, Shigeto; Funama, Yoshinori; Harada, Kazunori; Uemura, Sachiko; Yamashita, Yasuyuki

doi:10.2214/ajr.10.5698

Cited by 55 publications

(33 citation statements)

References 26 publications

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“…Because low kVp DECT increases image noise, contrast enhancement, and soft tissue contrast, Nakaura et al hypothesized that wide window width display settings would improve the image quality of low kVp CT. Their results also suggest that wide window width display settings are optimal for the inspection of low kVp scans. A wider window width might reduce the contrast in qualitative analysis because it displays a larger CT number range [7]. Our data suggest that low kVp images require a lower window level and width to reach the highest conspicuity.…”

Section: Discussionmentioning

confidence: 81%

“…Although a certain body circumference was regarded for the inclusion of patients, we did not consider this parameter in the statistical analysis. The most notable disadvantage of low-voltage CT is the potential for increased image noise (4,5,7,9,17) resulting from the lower tube energy, which results in unacceptable images in large patients. Beyond a certain patient size, the benefit of increased contrast and increased contrast-to-noise ratio (CNR) at 80 kV is offset by the increased noise and beam-hardening artifacts, thus making abdominal 80 kV single-source and dual-energy CT (using 80 kV in the lower energy tube) inadvisable [16,17].…”

Section: Discussionmentioning

confidence: 99%

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Improved Image Quality and Detectability of Hypovascular Liver Metastases on DECT with Different Adjusted Window Settings

Altenbernd

Forsting

Lauenstein

et al. 2016

Fortschr Röntgenstr

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ZUSAMMENFASSUNGZiel Untersuchung der Dual-Energy-Computertomografie (DECT) von hypovaskularisierten Lebermetastasen (LM) unter Berücksichtigung der Fensterwerteinstellungen (WS). Ziel der Studie ist zu untersuchen, inwiefern angepasster WS sowie die Niedrig-Energie-Datensätze der DECT die Erkennbarkeit insbesondere kleiner LM verbessern. This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited. Conclusion Low kVp images of DECT datasets are more precise in detecting hypovascular liver metastases than virtual 120 kVp images.Dedicated window settings have a relevant influence on conspicuity.Key points: ▪ DECT is a promising tool for detecting hypovascular liver metastases.▪ The diagnostic value of low kVp image data can be significantly increased by using special window settings. ▪ Use of only the low kVp images would lead to reduced radiation exposure. Citation Format

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Section: Discussionmentioning

confidence: 81%

Section: Discussionmentioning

confidence: 99%

Improved Image Quality and Detectability of Hypovascular Liver Metastases on DECT with Different Adjusted Window Settings

Altenbernd

Forsting

Lauenstein

et al. 2016

Fortschr Röntgenstr

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“…The improved tagging efficiency at One major difference between this study and previous studies is that patients were not excluded on the basis of enlarged body habitus; however, multiple prior studies have indicated that lowering tube voltage leads to a disproportionate increase in image noise and a decrease in image quality in larger patients because of a decrease in photon penetration (24,39). However, this should make the current study more widely applicable to a Western population than prior studies, many of which were performed in thinner Asian populations (34,37).…”

Section: Qualitative 3d Image Analysismentioning

confidence: 92%

“…Other studies have examined the effect of a decrease in tube voltage on intravenous contrast-enhanced applications, such as CT angiography, indirect CT venography, CT perfusion, and routine abdominal CT, and have shown that a decrease in tube voltage, at least in thinner patients, leads to a significant decrease in radiation dose by 13%-57% (16,19,20,22,(34)(35)(36)(37).…”

Section: Qualitative 3d Image Analysismentioning

confidence: 99%

“…Tube current can be increased to improve photon flux and decrease noise, albeit at a cost of some radiation dose savings. Dynamically altering or widening the picture archiving and communications system window and level settings can also decrease the visual perception of image noise (34). In addition, a decrease in tube voltage may also improve CNR for intravenous contrast-enhanced CT colonography as colonic polyps enhance.…”

Section: Qualitative 3d Image Analysismentioning

confidence: 99%

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Reducing Radiation Dose at CT Colonography: Decreasing Tube Voltage to 100 kVp

Chang¹,

Caovan²,

Grand³

et al. 2013

Radiology

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Purpose:To assess the effect of a decrease in tube voltage from 120 kVp to 100 kVp on dose, contrast-to-noise ratio (CNR), and three-dimensional (3D) image quality in patients undergoing computed tomographic (CT) colonography as well as to determine how these changes are affected by patient size. Materials and Methods:This HIPAA-compliant and institutional review board-approved retrospective study included 63 consecutive patients who underwent CT colonography and who waived informed consent. Scanning was performed with patients in the supine (120 kVp) and prone (100 kVp) positions, with other parameters unchanged. Volume CT dose index (CTDI vol ), dose-length product (DLP), image noise, attenuation of selected materials, and CNR were compared with the Wilcoxon matched-pairs signed rank test. Two readers blinded to tube voltage independently assessed 3D endoluminal image quality. The k coefficients were calculated for interobserver agreement. Average image quality ratings were compared with the Wilcoxon signed rank test. All recorded data were stratified by patient anteroposterior diameter to determine effects of patient size. Results:Decreasing tube voltage from 120 to 100 kVp resulted in a 20% decrease in CTDI vol (P , .001) and a 16% decrease in DLP (P , .001). Image noise increased by 32% (P , .001). Mean attenuation of tagged fluid increased from 395 to 487 HU (P , .001). There was no change in mean CNR of tagged fluid (17.1 at 120 kVp, 16.8 at 100 kVp; P = .37), regardless of patient size. The 3D image quality decreased slightly from a median score of 5 out of 5 to 4 out of 5 (P , .001). There was substantial interobserver agreement. Conclusion:A decrease in tube voltage from 120 to 100 kVp results in a significant decrease in radiation dose but only a minimal decrease in 3D image quality at all patient sizes.q RSNA, 2012

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Relationship between size‐specific dose estimates and image quality in computed tomography depending on patient size

Kawashima

Ichikawa

Hanaoka

et al. 2018

J Applied Clin Med Phys

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This study investigates the relationship between contrast‐to‐noise ratio (CNR) and size‐specific dose estimate (SSDE) in computed tomography (CT) depending on patient size. In addition, the relationship to the auto exposure control (AEC) techniques is examined. A tissue‐equivalent material having human‐liver energy dependence is developed and used to evaluate these relationships. Three exposure dose levels (constant CT dose index, constant SSDE, and with AEC) are tested using four different phantom sizes (diameter: 15, 20, 25 and 30 cm) in two different CT scanners (SOMATOM Definition Flash, Siemens, and LightSpeed VCT, GE). The contrast‐to‐noise ratios (CNRs) are measured using the developed phantom. It is found that the CNR increases with decreasing phantom size at constant SSDE, although the increase ratio is smaller than that of the constant CT dose index. This result indicates that the image characteristics differ even when the patient dose received from the CT examination is equivalent for each patient size. In the case of AEC use, the CNR results of the Siemens scanner exhibit a similar trend to those obtained for constant SSDE, for each phantom size. This suggests that the AEC technique that maintains a constant image quality (CARE Dose 4D) for each patient size corresponds well to the image quality obtained for constant SSDE. These findings facilitate further understanding of the relationship between image quality and exposure CT dose depending on patient size.

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Low-Kilovoltage, High-Tube-Current MDCT of Liver in Thin Adults: Pilot Study Evaluating Radiation Dose, Image Quality, and Display Settings

Abstract: At portal phase abdominal CT, 80 kVp and a high tube current-time product setting significantly improved image quality and reduced the radiation dose compared with 120 kVp.

Cited by 55 publications

References 26 publications

Improved Image Quality and Detectability of Hypovascular Liver Metastases on DECT with Different Adjusted Window Settings

Improved Image Quality and Detectability of Hypovascular Liver Metastases on DECT with Different Adjusted Window Settings

Reducing Radiation Dose at CT Colonography: Decreasing Tube Voltage to 100 kVp

Relationship between size‐specific dose estimates and image quality in computed tomography depending on patient size

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