TU-A-12A-07: CT-Based Biomarkers to Characterize Lung Lesion: Effects of CT Dose, Slice Thickness and Reconstruction Algorithm Based Upon a Phantom Study

2014 ◽  
Vol 41 (6Part26) ◽  
pp. 451-451
Author(s):  
B Zhao ◽  
Y Tan ◽  
W Tsai ◽  
L Lu ◽  
L Schwartz ◽  
...  
Keyword(s):  
Reconstruction Algorithm ◽  
Lung Lesion ◽  
Phantom Study ◽  
Slice Thickness ◽  
Ct Dose

scholarly journals Manual kidney stone size measurements in computed tomography are most accurate using multiplanar image reformatations and bone window settings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Robert Peter Reimer ◽  
Konstantin Klein ◽  
Miriam Rinneburger ◽  
David Zopfs ◽  
Simon Lennartz ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Treatment Decision ◽  
Reconstruction Algorithm ◽  
Slice Thickness ◽  
Reconstruction Algorithms ◽  
Stone Size ◽  
Bone Window ◽  
3D Printed ◽  
Measurement Strategies ◽  
Digital Caliper

AbstractComputed tomography in suspected urolithiasis provides information about the presence, location and size of stones. Particularly stone size is a key parameter in treatment decision; however, data on impact of reformatation and measurement strategies is sparse. This study aimed to investigate the influence of different image reformatations, slice thicknesses and window settings on stone size measurements. Reference stone sizes of 47 kidney stones representative for clinically encountered compositions were measured manually using a digital caliper (Man-M). Afterwards stones were placed in a 3D-printed, semi-anthropomorphic phantom, and scanned using a low dose protocol (CTDIvol 2 mGy). Images were reconstructed using hybrid-iterative and model-based iterative reconstruction algorithms (HIR, MBIR) with different slice thicknesses. Two independent readers measured largest stone diameter on axial (2 mm and 5 mm) and multiplanar reformatations (based upon 0.67 mm reconstructions) using different window settings (soft-tissue and bone). Statistics were conducted using ANOVA ± correction for multiple comparisons. Overall stone size in CT was underestimated compared to Man-M (8.8 ± 2.9 vs. 7.7 ± 2.7 mm, p < 0.05), yet closely correlated (r = 0.70). Reconstruction algorithm and slice thickness did not significantly impact measurements (p > 0.05), while image reformatations and window settings did (p < 0.05). CT measurements using multiplanar reformatation with a bone window setting showed closest agreement with Man-M (8.7 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05, r = 0.83). Manual CT-based stone size measurements are most accurate using multiplanar image reformatation with a bone window setting, while measurements on axial planes with different slice thicknesses underestimate true stone size. Therefore, this procedure is recommended when impacting treatment decision.

Effects of acquisition method and reconstruction algorithm for CT number measurement on standard-dose CT and reduced-dose CT: a QIBA phantom study

2019 ◽  
Vol 37 (5) ◽  
pp. 399-411
Author(s):  
Yoshiharu Ohno ◽  
Yasuko Fujisawa ◽  
Kenji Fujii ◽  
Naoki Sugihara ◽  
Yuji Kishida ◽  
...  
Keyword(s):  
Standard Dose ◽  
Reconstruction Algorithm ◽  
Phantom Study ◽  
Ct Number ◽  
Reduced Dose ◽  
Acquisition Method

scholarly journals CT dose optimization for the detection of pulmonary arteriovenous malformation (PAVM): A phantom study

2020 ◽  
Vol 101 (5) ◽  
pp. 289-297 ◽  
Author(s):  
J. Greffier ◽  
S. Boccalini ◽  
J.P. Beregi ◽  
A. Vlassenbroek ◽  
A. Vuillod ◽  
...  
Keyword(s):  
Arteriovenous Malformation ◽  
Phantom Study ◽  
Pulmonary Arteriovenous Malformation ◽  
Dose Optimization ◽  
Ct Dose

The effects of patient positioning when interpreting CT dose metrics: A phantom study

2017 ◽  
Vol 44 (4) ◽  
pp. 1514-1524 ◽  
Author(s):  
Rebecca M. Marsh ◽  
Michael S. Silosky
Keyword(s):  
Patient Positioning ◽  
Phantom Study ◽  
Ct Dose ◽  
Dose Metrics

scholarly journals Influence of X ray computed tomography (CT) exposure and reconstruction parameters on positron emission tomography (PET) quantitation.

2020 ◽  
Author(s):  
Ivan Ho Shon ◽  
Christopher Reece ◽  
Thomas Hennessy ◽  
Megan Horsfield ◽  
Bruce McBride
Keyword(s):  
Low Dose ◽  
Reconstruction Algorithm ◽  
Lung Tumour ◽  
Beam Hardening ◽  
Low Dose Ct ◽  
Ct Dose ◽  
Positron Emission ◽  
Significant Difference ◽  
Pet Reconstruction ◽  
The Impact

Abstract Background: The CT of PET CT provides diagnostic information, anatomic localisation and attenuation correction (AC). When only AC is required very lose dose CT is desirable. CT iterative reconstruction (IR) improves image quality with lower exposures however there is little data on very low dose IR CT for AC of PET. This work assesses the impact of CT exposure and reconstruction algorithm on PET voxel values.Method: An anthropomorphic torso phantom was filled with physiologically typical [18]F concentrations in heart, liver and background compartments. A 17mm diameter right lung “tumour” filled with [18]F was included (surrounding lung contained no 18[F]). PET was acquired followed by 24 CT acquisitions with varying CT exposures (15 - 50mAs, 80 – 120kVp, pitch 0.671 or 0.828). Each CT was reconstructed twice using filtered back projection (FBP) or IR and these used for AC of PET. The reference PET reconstruction (RR) used CT acquired at 50mAs, 120kVp, pitch 0.828, IR, all others were test PET reconstructions (TR). Regions of interest (ROIs) were drawn in liver, soft tissue and over “tumour” on each TR and compared with the RR. Voxel values in each TR were compared to the RR using a paired t-test and by calculating which and what proportion of voxels in each TR differed by a quantitatively significant difference (QSD) from the RR.Results: TRs reconstructed using lower dose CTs underestimated mean and maximum ROI activity relative to the RR; greater with IR than FBP. Once CT dose index (CTDI) increased to 1 mGy, differences were less than QSD. On voxel analysis all TRs were significantly different to the RR (p <0.0001). TRs reconstructed at the lowest CT exposure with IR had 6% of voxels that differed by greater than QSD. Differences were reduced with increasing CTDI and FBP reconstruction. Voxels which exceeded the QSD were spatially localised to regions of high activity, interfaces between different attenuation and areas of CT beam hardening.Conclusions: Very low dose CT exposures are feasible for accurate PET AC. Scanner and reconstruction specific validation should be employed prior very low dose CT AC for PET.

PO-1787 The Effect of Reducing CT Dose on Proton Therapy Dose Calculation – Phantom Study

2021 ◽  
Vol 161 ◽  
pp. S1512-S1513
Author(s):  
M. Elhamiasl ◽  
K. Salvo ◽  
E. Sterpin ◽  
J. Nuyts
Keyword(s):  
Proton Therapy ◽  
Dose Calculation ◽  
Phantom Study ◽  
Ct Dose

Detection of mild emphysema by computed tomography density measurements

2005 ◽  
Vol 46 (3) ◽  
pp. 237-245 ◽  
Author(s):  
J. Vikgren ◽  
O. Friman ◽  
M. Borga ◽  
M. Boijsen ◽  
S. Gustavsson ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Reconstruction Algorithm ◽  
Threshold Level ◽  
Slice Thickness ◽  
Healthy Male ◽  
High Resolution Computed Tomography ◽  
Diagnostic Ability ◽  
Density Measurements ◽  
Factors Influencing ◽  
Never Smokers

Purpose: To assess the ability of a conventional density mask method to detect mild emphysema by high‐resolution computed tomography (HRCT); to analyze factors influencing quantification of mild emphysema; and to validate a new algorithm for detection of mild emphysema. Material and Methods: Fifty‐five healthy male smokers and 34 never‐smokers, 61–62 years of age, were examined. Emphysema was evaluated visually, by the conventional density mask method, and by a new algorithm compensating for the effects of gravity and artifacts due to motion and the reconstruction algorithm. Effects of the reconstruction algorithm, slice thickness, and various threshold levels on the outcome of the density mask area were evaluated. Results: Forty‐nine percent of the smokers had mild emphysema. The density mask area was higher the thinner the slice irrespective of the reconstruction algorithm and threshold level. The sharp algorithm resulted in increased density mask area. The new reconstruction algorithm could discriminate between smokers with and those without mild emphysema, whereas the density mask method could not. The diagnostic ability of the new algorithm was dependent on lung level. At about 90% specificity, sensitivity was 65–100% in the apical levels, but low in the rest of the lung. Conclusion: The conventional density mask method is inadequate for detecting mild emphysema, while the new algorithm improves the diagnostic ability but is nevertheless still imperfect.

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