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目的对腹部肿瘤采用图像引导放射治疗(IGRT)技术以提高其放疗精度。方法应用Syn-ergyIGRT加速器治疗24例腹部肿瘤患者,通过锥形束CT(CBCT)影像技术获得患者左右(x)、头脚(y)、前后(z)方向的线性摆位误差以及分别以x、y、z轴旋转形成相应的u、v、w旋转摆位误差,分析其摆位误差。结果 24例患者共行458次CBCT,x、y、z、u、v、w轴自由度的系统误差±随机误差分别为(0.15±0.07)cm、(0.08±0.13)cm、(-0.02±0.12)cm、0.76°±0.25°、-0.20°±0.27°、0.20°±0.19°。其中y方向摆位误差最大、z方向次之、x方向摆位误差最小。x、y、z方向的摆位外扩分别为0.57cm、1.09cm、0.66cm。结论 IGRT的应用明显减少了腹部肿瘤患者的摆位误差,提高了治疗精度。为减少摆位误差影响,建议临床耙体积(CTV)外放计划耙体积(PTV)时,在x、y和z方向上分别外扩0.60cm、1.20cm和0.80cm。
Objective To improve the radiotherapy accuracy by imaging guided radiotherapy (IGRT) in abdominal tumors. Methods Twenty-four patients with abdominal tumors were treated with Syn-ergyIGRT accelerator. Linear positioning errors of left and right (x), head and neck (y) and anteroposterior (z) were obtained by cone beam computed tomography (CBCT) , Y, z axis rotation to form the corresponding u, v, w rotation setup error analysis of its setup error. Results The systematic error ± random error of CBCT, x, y, z, u, v, w axis degrees of freedom were (0.15 ± 0.07) cm, (0.08 ± 0.13) cm, 0.12) cm, 0.76 ° ± 0.25 °, -0.20 ° ± 0.27 °, 0.20 ° ± 0.19 °. Among them, the error in the y direction is the largest, the z direction is the second, and the error in the x direction is the smallest. In the x, y and z directions, the outward expansion is 0.57cm, 1.09cm and 0.66cm respectively. Conclusion The application of IGRT significantly reduces the setting errors of patients with abdominal tumors and improves the treatment accuracy. To reduce the effect of setup error, it is recommended that the clinical rake volume (CTV) extroverted by 0.60 cm, 1.20 cm and 0.80 cm in the x, y, and z directions, respectively, should be used when planning the rake volume (PTV).