Jiang S K, Wang J J, Wang H, Zhou S, Yang R J, Zhang R L, Lin L
Department of Radiation Oncology, Peking University Third Hospital, Beijing 100191, China.
Zhonghua Zhong Liu Za Zhi. 2021 Jan 23;43(1):155-159. doi: 10.3760/cma.j.cn112152-20190130-00057.
To investigate the effect of six degree of freedom (6-DOF) bed combined with cone beam computed tomography (CBCT) in the on-line correction of setup errors in patients with primary rectal cancer. The clinicopathological data of 17 patients with primary rectal cancer in Department of Radiotherapy, Third Hospital of Peking University from July 2013 to January 2014 were collected. There were 14 males and 3 females, a median age of 65 years. The difference of CBCT and 6-DOF bed combined with CBCT online correction of patients with positioning error were retrospectively analyzed. Before position correction, the first CBCT verification of setup errors in the three translation directions including X (left and right), Y (in and out) and Z (up and down) directions were (0.06±0.25) cm, (0.13±0.40) cm and (-0.28±0.31) cm, respectively. The setup errors of RX (rotation pitch), RY(rolling) and RZ (left and right rotation) directions were (0.62±1.15)°, (-0.19±0.99)°, and (-0.34 ± 0.84)°, respectively . After correction of IGRT combined with six freedom of bed, the setup errors of translation X, Y and Z were (0.01±0.09) cm, (-0.01±0.05) cm and (-0.03±0.08) cm, respectively, and the setup errors of rotation RX, RY and RZ directions were (-0.16±0.40)°, (0.36±0.31)°and (-0.01±0.25)°, respectively. There were significant differences in translation direction (X, Y and Z direction) and rotation direction (Rx, RY and RZ) before and after 6-DOF bed combined with CBCT correction (all <0.05). In the translation direction, the higher frequency range of Z-direction error value was 0.20-0.79 cm. In the rotation direction, the frequency range of error in Rx direction was 0.20°-2.99°. There was no significant difference between bone mode and gray scale model registration (>0.05). With the progress of radiotherapy, the setup errors of X, Z, Rx, RY and RZ directions increased except Y direction. In radiotherapy, six freedom bed combined with CBCT is helpful to correct the setup errors of patients with primary rectal cancer. Six freedom bed may be used to correct the setup errors of patients with primary rectal cancer online. Image-guided radiation therapy (IGRT) is recommended for bone pattern registration in patients with rectal cancer.
探讨六自由度（6-DOF）床联合锥形束计算机断层扫描（CBCT）在原发性直肠癌患者摆位误差在线校正中的作用。收集2013年7月至2014年1月北京大学第三医院放疗科17例原发性直肠癌患者的临床病理资料。其中男性14例，女性3例，中位年龄65岁。回顾性分析CBCT以及6-DOF床联合CBCT在线校正患者定位误差的差异。在进行摆位校正前，对包括X（左右）、Y（进出）和Z（上下）三个平移方向的摆位误差进行首次CBCT验证，其误差分别为（0.06±0.25）cm、（0.13±0.40）cm和（-0.28±0.31）cm。RX（旋转俯仰）、RY（滚动）和RZ（左右旋转）方向的摆位误差分别为（0.62±1.15）°、（-0.19±0.99）°和（-0.34±0.84）°。在采用六自由度床联合IGRT校正后，平移X、Y和Z方向的摆位误差分别为（0.01±0.09）cm、（-0.01±0.05）cm和（-0.03±0.08）cm，旋转RX、RY和RZ方向的摆位误差分别为（-0.16±0.40）°、（0.36±0.31）°和（-0.01±0.25）°。6-DOF床联合CBCT校正前后，平移方向（X、Y和Z方向）和旋转方向（Rx、RY和RZ）均有显著差异（均<0.05）。在平移方向上，Z方向误差值较高的频率范围为0.20 - 0.79 cm。在旋转方向上，Rx方向误差的频率范围为0.20° - 2.99°。骨模式与灰度模式配准之间无显著差异（>0.05）。随着放疗的进行，除Y方向外，X、Z、Rx、RY和RZ方向的摆位误差均增加。在放射治疗中，六自由度床联合CBCT有助于校正原发性直肠癌患者的摆位误差。六自由度床可用于在线校正原发性直肠癌患者的摆位误差。对于直肠癌患者，推荐采用图像引导放射治疗（IGRT）进行骨模式配准。
