基于头部锥形束CT图像两种方法进行剂量计算的准确性比较

A comparsion of accuracy for dose calculation based on head cone-beam CT image using two methods

目的比较基于头部锥形束CT(CBCT)图像两种方法进行剂量计算的准确性。方法采用器官容积赋值法和剂量形变对15例头部单发恶性肿瘤患者的首次治疗前CBCT图像进行剂量计算,并分别与计划CT图像的靶区和危及器官剂量学参数比较。结果与计划CT比较,器官容积赋值法的靶区剂量学参数均升高(P<0.01),剂量偏差均小于±1%。剂量形变的靶区剂量学参数(除大体肿瘤计划靶区的平均剂量和计划靶区的中位剂量、平均剂量外)与计划CT比较有统计学差异(P<0.05),剂量偏差均小于±0.5%。器官容积赋值法的脑干最大剂量低于计划CT(P<0.05),剂量偏差均小于±1%。剂量形变的危及器官剂量学参数(除眼球平均剂量外)与计划CT比较均有统计学差异(P<0.05),剂量偏差均小于±5%。结论利用器官容积赋值法和剂量形变对头部CBCT图像进行剂量计算,其精度可以满足临床应用标准,为剂量引导的自适应放疗提供保障。

Objective To compare the accuracy for dose calculation based on head cone-beam CT(CBCT)image using two methods.Methods Before first treatment,the dose calculations of CBCT images in 15 patients with single malignant head tumors were performed using the two methods of organ volume assignment and dose deformation,respectively.The results were compared with the dosimetric parameters of the planned CT images in the target areas and organs at risk.ResultsCompared with planned CT images,the target dosimetric parameters calculated with organ volume assignment were all increased with a dose deviation of less than±1%(P<0.01).Except for the mean dose of planing gross tumor volume and median dose and mean dose of planned tumor target,the target dosimetry parameters calculated with dose deformation were significantly different from those of planned CT(P<0.05)with a dose deviation of less than±0.5%.The brain stem maximum dose calculated with organ volume assignment was lower than that of planned CT(P<0.05)with a dose deviation of less than±1%.Except for ocular mean dose,the dosimetric parameters of the organs at risk calculated with dose deformation were significantly different from those of planned CT(P<0.05)with a dose deviation of less than±5%.Conclusion The accuracy for dose calculation based on head CBCT image using the two methods of organ volume assignment and dose deformation can meet the clinical application standards and provide a guarantee for dose-guided adaptive radiotherapy.