• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.7-18
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• 2017

Purpose: A QA Set was established to verify the movement accuracy of image-guided 6DoF Couch and to evaluate its usefulness. Materials and Methods: Two sets of linear accelerators equipped with 6DoF Couch and CBCT were used. Using the established QA Set, each CBCT image was obtained over 15 times through the Penta-Guide Phantom installed with off-set shift values along six translational (Translation; TX, TY, TZ) and rotational (Rotation, Pitch; RX, Roll; RY, Yaw; RZ) directions. Using this method, we compared the reference image and the registration image, and we analyzed the error calculated by measuring the positional accuracy of the modified 6DoF Couch. Results: The Air Cavity corresponding to the Pixel of the reference image and the registration image were all contained between 30 and 66, and the revealing high registration accuracy. Error between the modified off-set value of 6DoF Couch and the measured value along translational directions were $0.25{\pm}0.18mm$ in the TX direction, $0.25{\pm}0.25mm$ in the TY direction, and $0.36{\pm}0.2mm$ in the TZ direction. Misalignments along the rotational axis were $0.18{\pm}0.08^{\circ}$ in the RX direction, $0.26{\pm}0.09^{\circ}$ in the RY direction, and $0.11{\pm}0.08^{\circ}$ in the RZ direction, it was corrected precisely for any value. Conclusion: Using the YCC QA Set, we were able to verify the error of 6DoF Couch along both the translational and rotational directions in a very simple method. This system would be useful in performing Daily IGRT QA of 6DoF Couch.