TY - JOUR ID - 11425 TI - Dosimetric Effects of Rotational Setup Error in Volumetric Modulated Arc Radiotherapy on Brain Tumor Patients JO - Iranian Journal of Medical Physics JA - IJMP LA - en SN - AU - Park, Hyo-Kuk AU - Cho, Jae-Hwan AU - Kim, sungchul AD - Department of Radiation Oncology, Yonsei Cancer Center, Seoul AD - Department of Radiological Technology, Ansan University, Ansan AD - Radiological Science, Gachon University Medical Campus, Incheon, Korea Y1 - 2019 PY - 2019 VL - 16 IS - 2 SP - 171 EP - 178 KW - Volumetric modulated arc radiotherapy KW - Cone beam computed tomography KW - Setup error KW - Dose DO - 10.22038/ijmp.2018.32544.1392 N2 - Introduction: This study examined the dosimetric effects based on the rotational setup error to correct patient setup errors occur during volumetric modulated arc radiotherapy (VMAT) for brain tumor patients. Material and Methods: This study included 1129 cases of cone beam computed tomography (CBCT) images obtained from 46 brain tumor patients, who experienced VMAT and used the 6DoF (degree of freedom) treatment couch. The dosimetric effects regarding the application of the rotational setup error were examined by comparing the treatment plans. Results: The mean patient setup errors at the lateral (X-axis), longitudinal (Y-axis), and vertical (Z-axis) directions were 0.1±1.4, 0.0±1.1, and -0.4±1.2 mm, respectively. The pitch, roll, and yaw were -0.29±0.61°,-0.42±0.98°, and -0.53±0.69°, respectively. When an absolute value was taken for the setup error, the mean error was 1.06±0.14 mm at the three translation directions, and the error of rotation was 0.82±0.14°, showing a larger error than that of translation. In terms of the mean dose difference by each region of interest (ROI) before and after correcting for the rotational setup error on the treatment plan, Brain_max was 2.17 Gy, and Brain_mean was 0.28 Gy, whereas the maximum and mean of Brain_stem were -3.58 and -4.43 Gy, respectively. These findings suggested a dose difference according to the correction of the rotational setup error. Conclusion: This study indicated that the dose effect is influenced by the rotational setup error in VMAT of brain tumor patients. Moreover, the 6DoF positional correction could reduce the positional uncertainties and deliver a more accurate dose. UR - https://ijmp.mums.ac.ir/article_11425.html L1 - https://ijmp.mums.ac.ir/article_11425_f7495b3190236d3042094a330f125719.pdf ER -