Spectral CT and MRI Protocol for Radiotherapy

All CT studies were acquired in treatment positions on a Spectral CT (IQon, Philips Healthcare, Cleveland, Ohio) with 120 kVp, 0.36 pitch, 0.625-mm collimation, autoexposure control, and a 50 cm field of view. The images were reconstructed with an iterative algorithm (iDose4, level 2) to yield a pixel size of 0.98 by 0.98 mm² and a slice thickness of 1 to 2 mm. The T1W MRI_tx images were acquired in treatment position using a Turbo Field Echo sequence on 1.5T or 3T MRI systems (Ingenia, Philips Healthcare, Gainesville, Florida). To replicate treatment position, flexible-loop coils and a head-positioning overlay board were used to accommodate face masks and other immobilization devices, as described previously [10 (link)].