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目的利用机载千伏级锥形束CT(CBCT)研究不同定位方式对胸部肿瘤放疗的摆位误差。方法利用CBCT扫描,来测量患者X(左右方向)、Y(前后方向)、Z(上下方向)线性摆位误差,并计算总的摆位误差。结果各组患者在经CBCT校正后,在各个方向上的线性误差和总误差都要比校正前的误差有明显的减少。胸部热塑体罩的残留误差最小(P=0.06)。结论经过CBCT的校准,可以明显地减少三种固定方式的摆位误差。胸膜热塑体罩由于其良好的物理限制,经CBCT校准后它的残留误差最小,摆位精度最高。
Objective To study the placement error of chest radiotherapy with different positioning methods using on-board KV cone beam computed tomography (CBCT). Methods CBCT scanning was used to measure the linear misalignments of X (left and right), Y (front and back) and Z (up and down) and to calculate the total setup error. Results After the CBCT calibration, the linear error and the total error in all directions of the patients in each group were significantly lower than those before the correction. Chest thermoplastics cover the smallest residual error (P = 0.06). Conclusion After CBCT calibration, can significantly reduce the placement error of the three fixed ways. Due to its good physical limitations, the plethysmologic thermoplastic mask has the smallest residual error after CBCT calibration and provides the highest positioning accuracy.