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KMID : 0357520130360020123
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Journal of Radiological Science and Technology
2013 Volume.36 No. 2 p.123 ~ p.129
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A Study on Mechanical Errors in Cone Beam Computed Tomography(CBCT) System
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Yi-Seong Lee
Yoo Eun-Jeong
Kim Seung-Keun
Choi Kyoung-Sik
Lee Jeong-Woo
Suh Tae-Suk
Kim Jeong-Koo
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Abstract
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This study investigated the rate of setup variance by the rotating unbalance of gantry in image-guided radiation therapy. The equipments used linear accelerator(Elekta Synergy TM, UK) and a three-dimensional volume imaging mode(3D Volume View) in cone beam computed tomography(CBCT) system. 2D images obtained by rotating $360^{circ}$ 수식 이미지and $180^{circ}$ 수식 이미지 were reconstructed to 3D image. Catpan503 phantom and homogeneous phantom were used to measure the setup errors. Ball-bearing phantom was used to check the rotation axis of the CBCT. The volume image from CBCT using Catphan503 phantom and homogeneous phantom were analyzed and compared to images from conventional CT in the six dimensional view(X, Y, Z, Roll, Pitch, and Yaw). The variance ratio of setup error were difference in X 0.6 mm, Y 0.5 mm Z 0.5 mm when the gantry rotated $360^{circ}$ 수식 이미지 in orthogonal coordinate. whereas rotated$180^{circ}$ 수식 이미지 , the error measured 0.9 mm, 0.2 mm, 0.3 mm in X, Y, Z respectively. In the rotating coordinates, the more increased the rotating unbalance, the more raised average ratio of setup errors. The resolution of CBCT images showed 2 level of difference in the table recommended. CBCT had a good agreement compared to each recommended values which is the mechanical safety, geometry accuracy and image quality. The rotating unbalance of gentry vary hardly in orthogonal coordinate. However, in rotating coordinate of gantry exceeded the ${pm}1^{circ}$ 수식 이미지 of recommended value. Therefore, when we do sophisticated radiation therapy six dimensional correction is needed.
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KEYWORD
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IGRT, QA, gantry rotation balance, CBCT
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