The Impact of Obesity on Abdominal Ct Radiation Dose and Image Quality

Qurashi, Abdulaziz A.; Rainford, Louise; Alshamrani, Khalid M; Foley, Shane

doi:10.1093/rpd/ncy212

Cited by 13 publications

(7 citation statements)

References 25 publications

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“…Despite active dose-modulation, higher BMI is usually associated with lower EID-CT image quality due to higher image noise [25]. Our study reports similar findings for PCD-CT datasets: patients with higher BMI-values exhibited significantly higher image noise on both CT systems and at all analyzed PCD-VMI keV levels.…”

Section: Discussionsupporting

confidence: 85%

Optimal Conspicuity of Liver Metastases in Virtual Monochromatic Imaging Reconstructions on a Novel Photon-Counting Detector CT—Effect of keV Settings and BMI

et al. 2022

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In dual-energy CT datasets, the conspicuity of liver metastases can be enhanced by virtual monoenergetic imaging (VMI) reconstructions at low keV levels. Our study investigated whether this effect can be reproduced in photon-counting detector CT (PCD-CT) datasets. We analyzed 100 patients with liver metastases who had undergone contrast-enhanced CT of the abdomen on a PCD-CT (n = 50) or energy-integrating detector CT (EID-CT, single-energy mode, n = 50). PCD-VMI-reconstructions were performed at various keV levels. Identical regions of interest were positioned in metastases, normal liver, and other defined locations assessing image noise, tumor-to-liver ratio (TLR), and contrast-to-noise ratio (CNR). Patients were compared inter-individually. Subgroup analyses were performed according to BMI. On the PCD-CT, noise and CNR peaked at the low end of the keV spectrum. In comparison with the EID-CT, PCD-VMI-reconstructions exhibited lower image noise (at 70 keV) but higher CNR (for ≤70 keV), despite similar CTDIs. Comparing high- and low-BMI patients, CTDI-upregulation was more modest for the PCD-CT but still resulted in similar noise levels and preserved CNR, unlike the EID-CT. In conclusion, PCD-CT VMIs in oncologic patients demonstrated reduced image noise–compared to a standard EID-CT–and improved conspicuity of hypovascularized liver metastases at low keV values. Patients with higher BMIs especially benefited from constant image noise and preservation of lesion conspicuity, despite a more moderate upregulation of CTDI.

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Section: Discussionsupporting

confidence: 85%

Optimal Conspicuity of Liver Metastases in Virtual Monochromatic Imaging Reconstructions on a Novel Photon-Counting Detector CT—Effect of keV Settings and BMI

et al. 2022

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“…Therefore, DLR may be useful, especially for ultra-highresolution CT that requires higher computation power (38). In addition, the image noise is substantially increased at low radiation doses, especially when large objects are scanned (39). We found no significant correlation between the CTDI vol /BMI value and the difference in the noise, indicating that DLR yielded similar noise reduction effects irrespective of the radiation dose and the patient habitus.…”

Section: Calculation Timesmentioning

confidence: 76%

Deep Learning–based CT Image Reconstruction: Initial Evaluation Targeting Hypovascular Hepatic Metastases

Nakamura

Higaki

Tatsugami

et al. 2019

Radiology: Artificial Intelligence

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To evaluate the effect of a deep learning-based reconstruction (DLR) method on the conspicuity of hypovascular hepatic metastases on abdominal CT images. Materials and Methods:This retrospective study with institutional review board approval included 58 patients with hypovascular hepatic metastases. A radiologist recorded the standard deviation of attenuation in the paraspinal muscle as the image noise and the contrast-to-noise ratio (CNR). CNR was calculated as region of interest ([ROI] L − ROI T )/N, where ROI L is the mean liver parenchyma attenuation, ROI T , the mean tumor attenuation, and N, the noise. Two other radiologists graded the conspicuity of the liver lesion on a five-point scale where 1 is unidentifiable and 5 is detected without diagnostic compromise. Only the smallest liver lesion in each patient, classified as smaller or larger than 10 mm, was evaluated. The difference between hybrid iterative reconstruction (IR) and DLR images was determined by using a two-sided Wilcoxon signed-rank test. Results:The image noise was significantly lower, and the CNR was significantly higher on DLR images than hybrid IR images (median image noise: 19.2 vs 12.8 HU, P , .001; median CNR: tumors , 10 mm: 1.9 vs 2.5; tumors . 10 mm: 1.7 vs 2.2, both P , .001). The scores for liver lesions were significantly higher for DLR images than hybrid IR images (P , .01 for both in tumors smaller or larger than 10 mm). Conclusion:DLR improved the quality of abdominal CT images for the evaluation of hypovascular hepatic metastases.

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“…27 It has been reported that with the increase of cross-sectional dimensions of patients, the tube current in ATCM will increase accordingly to ensure the quality of CT images and may result in the increase of absorbed dose. 28 Hence, we compared the abdominal size of these patients by measuring the abdominal fat ratio (AFS) values, 29 which refers to the distance from the anterior spine to the anterior abdominal wall divided by the maximum distance from the outer edge of the rectus sheath to the dermis in the same CT image. To some extent, AFS also indicates the fat layer thickness/body circumference of a pregnant woman during pregnancy.…”

Section: Discussionmentioning

confidence: 99%

“…ATCM is aimed to adjust the tube current according to the attenuation characteristics of the patient on the premise of ensuring good image quality as well as reducing the radiation exposure 27 . It has been reported that with the increase of cross‐sectional dimensions of patients, the tube current in ATCM will increase accordingly to ensure the quality of CT images and may result in the increase of absorbed dose 28 . Hence, we compared the abdominal size of these patients by measuring the abdominal fat ratio (AFS) values, 29 which refers to the distance from the anterior spine to the anterior abdominal wall divided by the maximum distance from the outer edge of the rectus sheath to the dermis in the same CT image.…”

Section: Discussionmentioning

confidence: 99%

Patient‐specific fetal radiation dosimetry for pregnant patients undergoing abdominal and pelvic CT imaging

Liu

Xie

et al. 2023

Medical Physics

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Background: Accurate estimation of fetal radiation dose is crucial for riskbenefit analysis of radiological imaging, while the radiation dosimetry studies based on individual pregnant patient are highly desired. Purpose: To use Monte Carlo calculations for estimation of fetal radiation dose from abdominal and pelvic computed tomography (CT) examinations for a population of patients with a range of variations in patients' anatomy, abdominal circumference, gestational age (GA), fetal depth (FD), and fetal development. Methods: Forty-four patient-specific pregnant female models were constructed based on CT imaging data of pregnant patients, with gestational ages ranging from 8 to 35 weeks. The simulation of abdominal and pelvic helical CT examinations was performed on three validated commercial scanner systems to calculate organ-level fetal radiation dose. Results:The absorbed radiation dose to the fetus ranged between 0.97 and 2.24 mGy, with an average of 1.63 ± 0.33 mGy. The CTDI vol -normalized fetal dose ranged between 0.56 and 1.30, with an average of 0.94 ± 0.25. The normalized fetal organ dose showed significant correlations with gestational age, maternal abdominal circumference (MAC), and fetal depth. The use of ATCM technique increased the fetal radiation dose in some patients. Conclusion:A technique enabling the calculation of organ-level radiation dose to the fetus was developed from models of actual anatomy representing a range of gestational age,maternal size,and fetal position.The developed maternal and fetal models provide a basis for reliable and accurate radiation dose estimation to fetal organs.

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The Impact of Obesity on Abdominal Ct Radiation Dose and Image Quality

Cited by 13 publications

References 25 publications

Optimal Conspicuity of Liver Metastases in Virtual Monochromatic Imaging Reconstructions on a Novel Photon-Counting Detector CT—Effect of keV Settings and BMI

Optimal Conspicuity of Liver Metastases in Virtual Monochromatic Imaging Reconstructions on a Novel Photon-Counting Detector CT—Effect of keV Settings and BMI

Deep Learning–based CT Image Reconstruction: Initial Evaluation Targeting Hypovascular Hepatic Metastases

Patient‐specific fetal radiation dosimetry for pregnant patients undergoing abdominal and pelvic CT imaging

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