瓦里安Acuity模拟机在放射治疗摆位误差验证中的应用

Application of Varian Acuity Simulator in Verification of Setting Errors in Radiotherapy

目的探讨瓦里安Acuity模拟机在放射治疗摆位误差验证中的应用价值。方法随机选取2019年4月至2020年1月于医院使用瓦里安Acuity模拟机定位并复位的60例放射治疗患者,其中,头颈部肿瘤患者、胸部肿瘤患者、盆腔部肿瘤患者各20例,分析定位与CT扫描及复位与CT扫描前后(X轴)、左右(Y轴)、头脚(Z轴)方向的摆位误差,并根据公式计划靶体积(PTV)外放=2∑+0.7σ计算PTV外放值。结果头颈部放射治疗患者的摆位误差最小,胸部次之,盆腔部最大;头颈部和胸部肿瘤放射治疗患者两次摆位X、Y、Z轴方向的误差比较,差异均无统计学意义(P>0.05);盆腔部肿瘤放射治疗患者两次摆位X、Y轴方向的误差比较,差异均无统计学意义(P>0.05),但Z轴方向的误差比较,差异有统计学意义(P<0.05)。经计算,头颈部肿瘤X、Y、Z轴方向的PTV外放值分别为2.76、2.84、4.18 mm;胸部肿瘤X、Y、Z轴方向的PTV外放值分别为5.24、5.18、4.44 mm;盆腔部肿瘤X、Y、Z轴方向的PTV外放值分别为6.74、4.98、9.45 mm。结论瓦里安Acuity模拟机可以提供高效的位置验证效率和摆位误差值,为PTV外放的大小提供临床依据;头颈部和胸部放射治疗无需二次摆位验证,盆腔部肿瘤放射治疗有二次摆位验证的必要性。

Objective The application value of Varian Acuity simulator in verification of setting errors in radiotherapy was investigated.Methods Sixty patients who were positioned and reset with Varian Acuity simulator during the radiotherapy from April 2019 to January 2020 in the hospital were randomly selected,including 20 patients with head and neck tumors,20 patients with chest tumors,and 20 patients with pelvic tumors.The setting errors of positioning and CT scan,reset and CT scan in the anterior-posterior(X axis),left-right(Y axis),cranial-caudal(Z axis)directions were analyzed.The extended margin of planning target volume(PTV)was calculated according to the equation of the extended margin of PTV equals to 2∑+0.7σ.Results The setting errors of radiotherapy for head and neck was the smallest,for chest was the second smallest and for pelvic was the largest;When the setting errors in the X,Y,Z directions of the two-stage of head and neck radiotherapy and chest radiotherapy were compared,the differences were all not statistically significant(P>0.05);When the setting errors in the X,Y directions of the two-stage of pelvic radiotherapy were compared,the differences were not statistically significant(P>0.05),while the difference was statistically significant for the Z direction(P<0.05).The extended margin in the X,Y,Z directions for head and neck tumors were 2.76,2.84,4.18 mm,for chest tumors were 5.24,5.18,4.44 mm,for pelvic tumors were 6.74,4.98,9.45 mm.Conclusion The Varian Acuity simulator can provide high efficient position verification and setting errors,thus providing clinical basis for the size of PTV;head and neck radiotherapy and chest radiotherapy do not need two-stage validation,pelvic radiotherapy has the necessity of two-stage validation.