Med x alpha

Imaging of the fetuses were acquired using 1 of 2 micro-CT scanners located on-site (XTH 225 ST or Med-X Alpha; Nikon Metrology, Tring, United Kingdom), both equipped with a multimetal target. All imaging was undertaken by 1 of 4 trained members of the research team (S.C.S, J.C.H, A.G. or I.C.S). Fetuses were secured within the scanner using foam supports, moisture absorbent wrapping material, and Parafilm M (Bemis Company, Inc, Oshkosh, WI) to ensure mechanical stability. Imaging parameters varied according to fetal size, with X-ray energies and beam current ranging between 60 and 160 kV and 78 and 350 μA, respectively. Exposure times ranged from 88 to 1000 ms, with 1 X-ray frame per projection, with a total number of projections varying between 1066 and 3141.
Projection images acquired by the scanner were reconstructed using modified Feldkamp filtered back-projection algorithms with proprietary software (CTPro3D; Nikon Metrology, United Kingdom) and postprocessed using VGStudio MAX 3.0 (Volume Graphics GmbH, Heidelberg, Germany). Isotropic voxel sizes varied according to specimen size and magnification, ranging from 18.6 μm to 121.7 μm.

Imaging of the specimens were acquired using 1 of 2 micro-CT scanners located on-site (XTH 225 ST or Med-X Alpha; Nikon Metrology, Tring, United Kingdom), both equipped with a multi-metal target. All imaging was undertaken by trained researchers (I.C.S or S.C.S). Specimens were secured within the scanner using foam supports, moisture absorbent wrapping material, and Parafilm M (Bemis Company, Inc., Oshkosh, WI) to ensure mechanical stability.
Imaging parameters varied according to specimen size, with X-ray energies and beam current ranging between 100 and 120 kV and 133 and 180 mA, respectively. Exposure times ranged from 354 to 500 ms, with 2 X-ray frames per projection and total number of projections varying between 2,301 and 3,141. Projection images acquired by the scanner were reconstructed using modified Feldkamp filtered back-projection algorithms with proprietary software (CTPro3D; Nikon Metrology, United Kingdom) and post-processed using VGStudio MAX 3.0 (Volume Graphics GmbH, Heidelberg, Germany). Isotropic voxel sizes varied according to specimen size and magnification, ranging from 8.18 to 22.19 microns.

The geometries of the pediatric CVLs were reconstructed from high-resolution imaging. The tips of the devices (ranging from 30 to 50 mm in length) were scanned using microfocus computed tomography (micro-CT) (Med-X Alpha; Nikon Metrology, Tring, UK). During the scanning procedure, the tip was attached to a carbon fibre plate and secured in place with parafilm B (Bemis, Neenah, WI, USA) to ensure stability during image acquisition. Images were obtained with optimised factors of an x-ray energy of 100 kVp, current of 100 µA, exposure time of 500 ms, with an optimised number of projections for each examination and 4 frames per projection using a Tungsten target. Voxel sizes ranged between 15.29 and 26.22 µm, with each acquisition taking approximately 40 min.