应用锥形束CT研究鼻咽癌调强放射治疗计划靶区的增长

Study on the PTV growth of nasopharyngeal carcinoma IMRT by the application of CBCT

目的:探讨应用锥形束CT(CBCT)指导鼻咽癌调强放射治疗计划靶区(PTV)增长的精确性。方法:选取在医院接受静态调强放射治疗的35例鼻咽癌患者,于治疗前进行CBCT扫描重建与定位图像配准,获得患者的摆位误差数据。分析摆位误差数据,得到所有患者的总系统误差Σ及总随机误差σ。再利用vanHerk的PTV增长公式计算得到患者头脚(X)、左右(Y)和腹背(Z)的PTV增长值。结果:鼻咽癌调强放射治疗前CTV到PTV的增长精确值在X、Y和Z的3个方向分别为0.304 cm、0.383 cm和0.416 cm。结论:鼻咽癌患者CTV到PTV增长时可以针对各个中心及患者进行个体化的增长,而不是均匀的外扩一固定值,这样更有利于对患者进行精确放射治疗。

Objective:To explore the precision of cone beam computed tomography(CBCT)in guiding the growth of the planning target volume(PTV)of intensity modulated radiation therapy(IMRT)for nasopharyngeal carcinoma.Methods:35 patients with nasopharyngeal carcinoma who received static IMRT in hospital were selected,and CBCT scan reconstruction and positioning image registration were performed before the treatment so as to obtain the positioning error data of patients.And the total system errorΣand total random errorσof all patients were obtained by analyzing the set-up error data.Then van Herk's PTV growth formula was used to calculate and obtain the PTV growth values of headfoot(X),left-right(Y)and abdomen-back(Z)of patients.Results:The precise values of the growth from CTV to PTV before IMRT for nasopharyngeal carcinoma were 0.304 cm,0.383 cm and 0.416 cm on the three directions of X,Y and Z,respectively.Conclusion:The growth from CTV to PTV of patients with nasopharyngeal carcinoma can implement individual growth for each center and patients but not uniformly expands a determine value out from center,which is more conducive to implement precisely radiotherapy.