Lightspeed rt ct scanner

All CT scans were acquired using a Philips Brilliance CT Big Bore or a GE LightSpeed RT CT scanner. Patients were positioned in the supine position and immobilized with a thermoplastic mask. High-resolution contrast-enhanced helical CT scans were then obtained with an x-ray tube voltage of 120 kV. The slice thickness was set as 3 mm or 5 mm in the Philips CT scanner and 2.5 mm or 5 mm in the GE CT scanner.

All patients lay supine with their arms raised and were immobilized with a system consisting of a vacuum bag, thermoplastic body shell, and carbon base plate with a size of 185 × 50 × 3 cm (length × width × height) (ESN-1800; Engineering System, Nagano, Japan). Patients were instructed to breathe shallowly for 1 minute to form a body shell. AC was applied in all patients to achieve reproducible tumor motion for planning and treatment; an in-house beaded cushion was inserted inside the formed body shell for AC. Multiphasic contrast-enhanced CT and slow CT were performed during the free-breathing using a LightSpeed RT CT scanner (GE Medical Systems, Waukesha, WI). Contrast-enhanced scans with the helical mode (rotation time: 1 s) were performed 30, 45, 70, and 180 s after the intravenous administration of a contrast agent (Iopamiron 300, Bayer Schering Pharma, Osaka, Japan) at a rate of 3 mL/s. A slow CT scan with the axial mode (rotation time: 4 s) was performed immediately after the completion of these contrast-enhanced scans. Both sets of CT data were reconstructed in a field of view (FOV) of 65 cm with a 2.5-mm slice thickness. All CT images were exported to the Pinnacle³ treatment planning system (version 9.2; Phillips Radiation Oncology Systems, Fitchburg, WI) and were registered by hardware arrangement.