Somatom edge plus

The standard non-contrast CT of the osseous pelvis without tin filtration was part of the clinical routine imaging workup at Balgrist University Hospital either on a 64-slice CT scanner (SOMATOM Definition AS, Siemens Healthineers) or on a 128-slice CT scanner (SOMATOM Edge Plus, Siemens Healthineers). On both CT scanners, images were acquired with automated tube voltage selection (CARE kV, reference 120kV) and tube current modulation (CARE Dose4D, reference 147mAs), a collimation width of 0.6 mm, a rotation time of 0.5 s, and a pitch of 0.8.
After the standard CT, all study participants received a non-contrast ultra-low-dose pelvic CT with tin filtration (protocol Sn140kV/50mAs) of the same coverage in the z-axis on the 128-slice CT scanner (SOMATOM Edge Plus, Siemens Healthineers) either at Balgrist University Hospital or at the Swiss Center for Musculoskeletal Imaging. The ULD-CT protocol was developed in pelvic cadavers, which is shown in the supplementary material. Settings of the ULD-CT protocol were as follows: a fixed tube voltage of 140 kV with tin filtration (Sn), fixed tube current of 50mAs, collimation width of 0.6 mm, rotation time of 1 s, and a pitch of 0.8.
Both the standard CT and ULD-CT were acquired in supine position with 15° internal rotation of the legs.

CT scan was performed based on the clinical judgment of the attending physician and was performed in the supine position, and the image was taken in the craniocaudal direction. In total, 47 of the CT examinations were conducted at our institution, and SOMATOM Edge Plus (Siemens Healthcare GmbH, Erlangen, Germany) with 64-detector rows was utilized. Conversely, 32 CT examinations were conducted outside our institutions, and several CTs with 4- to 320-detector rows were utilized. The acquisition parameters at our hospital were as follows: 120-kV tube voltage with automatic tube current modulation (150 mAs); tube rotation time, 0.28 s; beam collimation, 128 ch × 0.6 mm; and beam pitch, 1.5. By default, 2.0 mm chest CT images without interslice gap were reconstructed using a sharp tissue kernel (Bl57) and the filtered back-projection technique. Outside institutions, the slice thickness of the reconstructed images ranged from 1.25 to 5 mm.