容积密度分配法剂量计算可行性研究

Study of the feasibility and precision in dose calculation with the method of bulk density assignment

目的评估采用容积密度分配法进行剂量计算的可行性。方法选取本科放疗的16例鼻咽癌和19例食管癌患者，对定位CT计划进行容积密度分配法重新制作计划，根据靶区和危及器官受量及剂量体积直方图比较新计划与原计划的剂量分布差异。两种计划的剂量比较行配对t检验。结果采用容积密度分配法后的计划与定位CT计划相比靶区及危及器官剂量差异鼻咽癌患者均〈1％、食管癌患者均〈2％。结论初步结果证实采用容积密度分配法可以进行剂量计算。

Objective To study investigate the dose accuracy that can be achieved with the method of bulk density assignment. Methods Sixteen cases of nasopharyngeal cancer patients and nineteen cases of esophageal cancer patients who accept radiotherapy in our department were selected. The planning CT images with bulk density assignment to different classes of tissues were applied to calculate the dose distributions, and then the resulting dose volume histograms （DVH） of the tumor and organs of risk were compared with the original treatment plan . The paired t - test was taken for dose comparison between two plans . Results The DVH comparison based on the planning CT and the bulk density assignment CT showed good agreements. With nasopharyngeal cancer patients, differences between the two plans about target and normal tissue were less than 1%. With esophageal cancer patients, the dose differences were less than 2%. Conclusion Preliminary results confirm that the bulk density assignment method can be applied to calculate the dose distributions.