![]() Methods: Two test plans recommended by TG148 were chosen for this study. Purpose: To develop a filmless methodology based on an ArcCheck for QA measurement of the couch translation per gantry rotation and couch speed of a Tomotherapy unit. SU-F-T-457: A Filmless Method for Measurement of Couch Translation Per Gantry Rotation and Couch Speed for Tomotherapy Using ArcCheck In this study, the 4DCBCT images with different gantry rotation speed were evaluated. Advances in knowledge: Usually, the gantry rotation period of Elekta 4DCBCT system is kept constant at 4 min (50° min−1) for acquisition, and any attempt of decreasing/increasing the acquisition duration requires careful investigation. The phantom study demonstrated that 4DCBCT with slow gantry rotation showed better image quality and less ITV deviation. ![]() Conclusion: The impact of gantry rotation speed has to be considered when using 4DCBCT for ITV definition. Similarly, the image quality indicators such as spatial resolution, contrast-to-noise ratio and uniformity also degraded with increasing gantry rotation speed. Results: Compared to 4DCT, the average CBCT underestimated the ITV. In addition, the image quality of 4DCBCT was also evaluated for various gantry rotation speeds using Catphan® 600 (The Phantom Laboratory Inc., Salem, NY). ITVs obtained from average CBCT were compared with the four-dimensional CT (4DCT). Owing to the technical limitation of 4DCBCT system, average cone beam CT (CBCT) images derived from the 10 phases of 4DCBCT were used for the internal target volume (ITV) contouring. A dynamic thorax phantom with tumour mimicking inserts of diameter 1, 2 and 3 cm was programmed to simulate the respiratory motion (4 s) of the target. Methods: All the 4DCBCT image acquisitions were carried out in Elekta XVI Symmetry™ system (Elekta AB, Stockholm, Sweden). ![]() Objective: The purpose of this work was to evaluate the four-dimensional cone beam CT (4DCBCT) imaging with different gantry rotation speed. Maria Das, K J Mohamed Ali, Shajahan Agarwal, Arpita Mishra, Surendra P Kumar, Shaleen Evaluating the four-dimensional cone beam computed tomography with varying gantry rotation speed ![]()
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