Ge explore ct120

The GE eXplore CT120 (GE Healthcare, London, Ontario, Canada) was adapted to radiotherapy delivery by adding a two-stage iris collimation system (Rodriguez et al 2009 (link)). This system utilizes a pulsed x-ray beam running a ~10% duty cycle with a 0.3 mm focal spot for imaging, in contrast to using a continuous imaging beam on the PXi and Xstrahl units (Zhou et al 2010 (link)). The amorphous silicon flat panel detector has a pixel size of 49 μm and the SID and SSD are 35.4 cm and a 45 cm, respectively. MicroCT imaging on the GE eXplore CT120 scanner is performed with tube voltages between 70 and 120 kVp and radiotherapy with the maximum tube voltage of 120 kVp and tube current of 60 mA, using 1–10 cm diameter circular collimation with ~2 Gy min⁻¹ maximum output. The GE eXplore CT/RT140 microCT imaging is performed in similar fashion to the imager of the GE eXplore CT120 scanner (Jensen et al 2013 (link)). Radiotherapy is performed at 140 kVp with a 1.0 mm focal spot with a set of computerized independent jaws and the same SID as the eXplore CT120.

The animals were anesthetized and placed in ventral recumbancy on the GE LightSpeed 16 Slice CT scanner (GE Medical Systems). The scans (0.625 mm resolution, 120 kV) were conducted on all animals at 2 months pre-surgery, immediately, and at 6 weeks, 3 months, and 6 months following surgery. μCT imaging (50 μm resolution, 100 kV) of harvested RCUs was done using the GE Explore CT-120 (GE Medical Systems) at an external facility (Cornell University Imaging Facility), in a blinded fashion. Condyle height and bone volume were measured using the Mimics software (Materialise). Quantitation of bone volume and bone volume fraction was conducted by determining the amount of bone in the defect area based on the difference between the CT of pre- and post- surgery and the amount of bone removed.
μCT was performed by using a modified protocol (47 (link)), and the samples were scanned at 21-μm isotropic resolution. The bone volume was obtained from the application of a global thresholding technique so that only the mineralized tissue was detected. There was no difficulty in distinguishing the grafted material from the miniplates and screws used for fixation, which appeared in μCT as compact and geometrically defined structures. Spatial resolution of the full-voxel model was sufficient for evaluating the microarchitecture of the bone tissue.