Precision of dosimetry‐related measurements obtained on current multidetector computed tomography scanners

Mathieu, Kelsey Boitnott; McNitt-Gray, Michael F.; Zhang, Di; Kim, Hee Jin; Cody, Dianna D.

doi:10.1118/1.3426000

Cited by 16 publications

(17 citation statements)

References 10 publications

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“…By using a MC model, this experimental limitation can be overcome although the MC model needs to be validated against measurements or other independent calculations before use. Mathieu et al's study 37 will help to understand the precision of dosimetric-related measurements for the MDCT scanners.…”

Section: Discussionmentioning

confidence: 99%

Characteristics of x-ray beams in two commercial multidetector computed tomography simulators: Monte Carlo simulations

et al. 2011

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Section: Discussionmentioning

confidence: 99%

Characteristics of x-ray beams in two commercial multidetector computed tomography simulators: Monte Carlo simulations

et al. 2011

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“…These fi ndings may be attributable to the fact that the large cone angle used in the 320-detector scanner leads to a smaller contribution of overbeaming to the total dose, as well as to the fact that there was no overranging, as seen in helical acquisitions ( 19 ). Meanwhile, the radiation dose of a 64-detector scanner might vary in individual scanners and by manufacturer ( 22 ); therefore, the difference between the 320-detector scanner and other scanners might also be different.…”

Section: Gastrointestinal Imaging: Ct Of the Pancreas Goshima Et Almentioning

confidence: 96%

CT of the Pancreas: Comparison of Anatomic Structure Depiction, Image Quality, and Radiation Exposure between 320-Detector Volumetric Images and 64-Detector Helical Images

Goshima¹,

Kanematsu²,

Nishibori³

et al. 2011

Radiology

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Purpose:To prospectively compare 320-detector volumetric and 64-detector helical computed tomographic (CT) images of the pancreas for depiction of anatomic structures, image noise, and radiation exposure. Materials and Methods:This study was approved by the institutional review board, and written informed consent was obtained. A total of 154 patients (85 men, 69 women; age range, 26-85 years; mean age, 67 years) who underwent biphasic (arterial and pancreatic phase) contrast material-enhanced CT performed with a 320-detector scanner were randomized into two groups: the 320-detector group and the 64-detector group. Biphasic transaxial multiplanar reformatted images and volume-rendered CT angiograms were obtained. CT numbers in the abdominal aorta, pancreas, and abdominal wall fat tissue; signal-to-noise ratio (SNR); and dose-length product (DLP) were compared. In addition, image quality and focal lesion depiction ( n = 35) were qualitatively determined in the two groups. Unpaired t and Mann-Whitney tests were used for quantitative and qualitative assessment, respectively. Results:No signifi cant difference in CT numbers of the abdominal aorta and pancreas was noted between the two groups. Mean DLP was 43% lower in the 320-detector group (675.4 mGy·cm) than in the 64-detector group (1187.8 mGy·cm) ( P , .001 ). SNR of the abdominal aorta, pancreas, and abdominal wall fat on biphasic images was signifi cantly lower in the 320-detector group than in the 64-detector group ( P , .001). Image quality was acceptable in both groups and was slightly better in the 64-detector group for pancreatic phase axial images ( P = .02) and arterial phase multiplanar reformatted images ( P , .01). No signifi cant difference was found in the depiction of pancreatic parenchyma, main pancreatic duct, focal pancreatic lesions, splanchnic arteries, or most of the small splanchnic arterial branches. Conclusion:A 320-detector CT scan facilitates fast volumetric contrastenhanced CT of the entire pancreas with acceptable image quality, even though SNR was signifi cantly lower at 320-detector volumetric scanning.q RSNA, 2011 1

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“…Since the indicated

{CTDI}_{vol}

has a tolerance of 20% according to the related International Electrotechnical Commission (IEC) standard, (18)

{CTDI}_{vol}

may actually have to be measured by a method standardized by IEC (19) when a higher accuracy is desired. However, it has been reported that the relative disagreement between nominal and measured

{CTDI}_{vol}

values is under 5%, except in the case of a pediatric abdomen protocol, (20) and that relative errors for repeated weighted CT dose index measurements are also under 5% (21) . On the basis of these results, we decided to use the scanner‐indicated

{CTDI}_{vol}

values.…”

Section: Methodsmentioning

confidence: 99%

A phantom study investigating the relationship between ground‐glass opacity visibility and physical detectability index in low‐dose chest computed tomography

Ichikawa

Kobayashi

Sagawa

et al. 2015

J Applied Clin Med Phys

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In this study, the relationship between ground‐glass opacity (GGO) visibility and physical detectability index in low‐dose computed tomography (LDCT) for lung cancer screening was investigated. An anthropomorphic chest phantom that included synthetic GGOs with CT numbers of ‐630 Hounsfield units (HU; high attenuation GGO: HGGO) and ‐800 HU (low attenuation GGO: LGGO), and three phantoms for physical measurements were employed. The phantoms were scanned using 12 CT systems located in 11 screening centers in Japan. The slice thicknesses and CT dose indices (CTDIvol) varied over 1.0–5.0 mm and 0.85–3.30 mGy, respectively, and several reconstruction kernels were used. Physical detectability index values were calculated from measurements of resolution, noise, and slice thickness properties for all image sets. Five radiologists and one thoracic surgeon, blind to one another's observations, evaluated GGO visibility using a five‐point scoring system. The physical detectability index correlated reasonably well with the GGO visibility (R2=0.709,p<0.01 for 6 mm HGGO and R2=0.646,p<0.01 for 10 mm LGGO), and was nearly proportional to the CTDIvol. Consequently, the CTDIvol also correlated reasonably well with the GGO visibility (R2=0.701,p<0.01 for 6 mm HGGO and R2=0.680,p<0.01 for 10 mm LGGO). As a result, the CTDIvol was nearly dominant in the GGO visibility for image sets with different reconstruction kernels and slice thicknesses, used in this study.PACS numbers: 81.70.Tx, 87.57.Q‐

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Precision of dosimetry‐related measurements obtained on current multidetector computed tomography scanners

Abstract: From a dosimetry perspective, the MDCT scanners tested in this study demonstrated a high degree of within-run, between-run, and between-scanner precision (with relative precision errors typically well under 5%).

Cited by 16 publications

References 10 publications

Characteristics of x-ray beams in two commercial multidetector computed tomography simulators: Monte Carlo simulations

Characteristics of x-ray beams in two commercial multidetector computed tomography simulators: Monte Carlo simulations

CT of the Pancreas: Comparison of Anatomic Structure Depiction, Image Quality, and Radiation Exposure between 320-Detector Volumetric Images and 64-Detector Helical Images

A phantom study investigating the relationship between ground‐glass opacity visibility and physical detectability index in low‐dose chest computed tomography

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