To investigate the dependence of CT texture features on the number of gray levels, Ng, 51 texture features including GLCM (24), GLRLM (11), GLSZM (11) and NGTDM (5) were extracted with resampled Ng values of 16, 32, 64, 128 and 256. Spherical ROIs of 14.2 cm3 were contoured on 10 different cartridges within the CT scan image of the phantom. In addition, 2 rectangular ROIs, one of 50 cm3 (3 adjacent cartridges: ABS20, rubber and wood) and the other of 60 cm3 (5 adjacent cartridges: rubber, natural cork, solid acrylic, dense cork and 3D printed plaster) were contoured to further evaluate the impact of gray level discretization on texture features extracted from larger ROIs made up of multiple materials. The phantom CT scan used was acquired with the Siemens Definition AS scanner with pixel size, slice thickness, mAs, pitch and kVp of 0.49 mm, 3 mm, 250 mAs, 1.0 and 120 kVp, respectively, for all 12 ROIs. The %COV for each feature was calculated and features having %COV ≤ 20 and %COV > 20 were classified as reproducible and not reproducible, respectively. Finally, some of the texture features were normalized by the number of gray levels.
Definition as scanner
Manufactured by Siemens
Sourced in Germany
The Definition AS scanner is a medical imaging device designed for computed tomography (CT) scans. It is capable of generating high-resolution cross-sectional images of the body. The core function of the Definition AS scanner is to provide detailed and accurate diagnostic information to healthcare professionals.
Automatically generated - may contain errors
4 protocols using definition as scanner
1
Evaluating CT Texture Features Reproducibility
2
CT Imaging for Bronchial Thermoplasty Evaluation
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Non-contrast CT Scanning was performed on a 128-slice Siemens Definition AS + scanner with a helical slice thickness of 0.6 mm, rotation time of 0.6 s, detector coverage of 38.4 mm, and tube voltage of 100 kV. Two breath-hold scans were performed on each occasion—one at full inspiration, and the other at Functional Residual Capacity (FRC). All imaging was performed in a stable state, pre-bronchodilator, and prior to peri-procedural oral steroid administration. Post-acquisition, CT images were analysed independently to the investigating team by FLUIDDA (Kontich, Belgium), using Mimics (Materialise, Leuvin, Belgium), which converted the CT images into patient-specific, 3D computer models of the lung lobes and the airway dimensions [23 (link)]. The airways were partitioned into two, namely, the trachea and major bronchi which are not treated by BT, and the lobar and more distal airways down to 1-2 mm (the limits of resolution of the CT imaging), being the airways potentially treatable by BT. CT imaging was performed at baseline, and then repeated after completing BT treatment to the left lung, but prior to any BT treatment to the right lung.
3
Chest CT for COVID-19 Assessment
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Chest CT of group A was performed using a dedicated Siemens Definition AS + scanner (Siemens Healthineers, Forchheim D). This scanner was used solely for COVID-19 assessment to minimise the risk of cross-infection and contamination. The acquisition parameters were 120 ref.Kv, 60 ref.mAs, CarekV and CareDose activated, rotation time 0.3 second, and pitch 1.45.
Group B was scanned using a Siemens Definition Flash scanner. The acquisition parameters were 120 ref.Kv, 65 ref.mAs, CarekV, and CareDose activated, rotation time 0.28 second, and pitch 1.5.
CTDIVol was documented for both groups as an indicator of the radiation dose.
Group B was scanned using a Siemens Definition Flash scanner. The acquisition parameters were 120 ref.Kv, 65 ref.mAs, CarekV, and CareDose activated, rotation time 0.28 second, and pitch 1.5.
CTDIVol was documented for both groups as an indicator of the radiation dose.
4
Standardized CT and DXA Imaging Protocols
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The CT scans were carried out using a Siemens SOMATOM 128, Definition AS + scanner (Siemens Healthcare, Forchheim, Germany). The standardized protocol for each scan entailed a single-energy CT scan with settings at 120 kVp and 247 mA, featuring a dose modulation with a 0.6 mm collimation. The effective pitch was maintained at 0.8, and the reconstruction kernel employed was B60 (sharp). For the spine CT scans, which were executed without the use of contrast, a reconstructed slice thickness of 5.0 mm was consistently preserved.
For the DXA scans, a standard device was utilized, adhering to a conventional protocol (GE Lunar Prodigy, GE Healthcare). The subsequent reports were produced using vendor-specific software (Physicians Report Writer DX; Hologic, Discovery WI, USA). The strict adherence to standardized imaging protocols throughout the study guarantees the reproducibility and uniformity of our results.
For the DXA scans, a standard device was utilized, adhering to a conventional protocol (GE Lunar Prodigy, GE Healthcare). The subsequent reports were produced using vendor-specific software (Physicians Report Writer DX; Hologic, Discovery WI, USA). The strict adherence to standardized imaging protocols throughout the study guarantees the reproducibility and uniformity of our results.
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