【摘要】 目的　提出一种对包绕脊髓的凹形靶区的放疗布野方法。方法　在三维计划系统所提供的射野方向观视功能的引导下 ,对圆柱形石蜡模体中预设的包绕危险器官的凹形靶区采用多方向切线布野方式 (射野外界和内界分别和靶区与脊髓的外缘相切 )进行计划设计 ,并用胶片和电离室对计划所计算出的剂量分布和选取点的绝对剂量进行验证。同时选取位于不同部位的内含脊髓的凹形靶区进行计划设计 ,以对该布野方法的实际应用进行说明。结果　模体和病例的靶区剂量分布均匀 ,模体中危险器官的平均剂量不超过处方剂量的 16 % ,靶区与危险器官之间的剂量跌落梯度每毫米 >8% ,模体中剂量的计算值与实测结果符合性好 ,高剂量区剂量分布位置误差 <4mm ,绝对剂量误差 <5 %。结论　切线布野方法在治疗包含脊髓的凹形靶区中是切实可行的。更多还原

【Abstract】 Objective To provide a method of radiotherapy field arrangement f or concave paraspinal target. Methods Plan was designed for concave target in wa x phantom and the selected patients by the guidance of beam eye view (BEV) provi ded by a 3D treatment planning system (CREAT EXPERT). In BEV, the inner border o f all tangential fields was 2?mm out of the organ at risk (OAR) and the outer b or der was 5?mm beyond the target. Dosimetry films and ion chamber were used to ve ri fy the dose distribution and point dose in the wax phantom. Results Dose distr ibution in phantom and patient was homogeneous. The mean dose of OAR in phantom did not exceed 16% of the prescribed dose. Isodose curves dropped more than 8% p er?mm between the target and OAR in the phantom. Film dosimetry coincided well w ith the calculated results. Position error in high dose region was within 4?mm an d absolute dose errors were no more than 5%. Conclusion Tangential field arra ngement is valuable and practical in radiotherapy for concave paraspinal targets .更多还原