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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。
OBJECTIVE: To propose a radiotherapy method for the concave target area surrounding the spinal cord. Methods Guided by the visual field function provided by the three-dimensional planning system, a multi-directional tangent pattern was applied to the preset concave target area surrounding the dangerous organ in the cylindrical paraffin motif (field outside and inside Respectively, and the target area and the outer edge of the spinal cord tangent) of the planned design, and the film and ionization chamber of the planned dose distribution calculated and the absolute dose of selected points to verify. At the same time, we selected the concave target region containing the spinal cord in different parts to plan the practical application of the cloth field method. Results The dose distribution of phantom and case was uniform. The average dose of dangerous organs in the phantom was no more than 16% of the prescribed dose, and the dose drop gradient between the target area and the dangerous organs was> 8% per millimeter. The dose of phantom The calculated values are in good agreement with the measured results. The error of dose distribution in high dose area is less than 4 mm and the absolute dose error is less than 5%. Conclusions The tangential method is feasible in the treatment of concave target areas containing the spinal cord.