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Quantifying gantry rotation speed and gating effects on CBCT isocenter accuracy for radiotherapy image acquisition
Alex T Price1,2, Kenneth W Gregg1, Theodore H Arsenault1,3
1University Hospitals Seidman Cancer Center, 11100 Euclid Ave, Cleveland, OH 44106, USA.
None:
The Varian TrueBeam v4.1 enables a faster gantry rotation speed (9 deg/s) than previous versions (6 deg/s). In this longitudinal study, we assessed the impact of gantry rotation speed, fan geometry, and gating on imaging isocenter stability over 1 year. A ball bearing (BB) was CBCT imaged and raw projections were analyzed to extract BB displacement at each projection angle. The average BB displacement was 0.04 ± 0.03 mm. The maximum displacement of the BB was 0.15 mm, which is within 1.00 mm isocenter tolerances. Increased gantry rotation speed does not have a clinically meaningful impact on imaging isocenter stability.
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