Abstract
Materials/Methods: We have developed a 4D CBCT acquisition technique to support IGRTfor free-breathing thoracic andabdominal cancer patients. The Varian OBI imager was displaced (half-fan acquisition geometry) extending the FOV to 450 mm. The projections were acquired in 360 gantry rotation arcs. The 8 to 12 minute scanning time was set to cover 120 breathing cycles (BC), with a sampling rate of 20 projections per BC. We used the Varian Real-time positioning and management system as an external surrogate to correlate the patient respiration with the projection acquisition. View aliasing artifacts for single and multiple gantry arc acquisitions were evaluated on patient datasets. Using a synthetic 4D CBCT dataset derived from a 10 minute scan, we evaluated the distribution of gantry angle increments as a function of number of gantry rotations assuming 1 minute rotation time and 10 frames per second. Actual patient respiratory traces were used to sort the projections into phase bins. IQ was assessed as function x-ray exposure (mAs) per projection.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
