一种用于调强剂量计算的快速CBCT HU值修正方法

A Fast CBCT HU Value Correction Method for Dose Calculations of Intensity Modulated Radiotherapy

目的建立一种快速CBCT HU值修正方法,并将其应用于实际患者调强剂量计算。方法取10例头颈计划,获取患者的计划CT和第一次治疗时的CBCT图像。利用Eclipse计划系统进行配准并将CT图像上勾画的轮廓结构拷贝至CBCT图像。统计CBCT和CT上各轮廓的平均HU值,建立HUCBCT-UCT关系曲线,从而获取CBCT对应的CT值-电子密度曲线。另外选取5例头颈病例对其CBCT图像进行修正前后剂量进行计算,并与计划CT的剂量分布进行Gamma一致性比较和DVH比较。结果修正后的CBCT剂量计算结果与CT剂量计算结果相一致,Gamma一致性验证结果提高约4.4%,PTV平均剂量差异小于0.56%。结论本文的CBCT HU值修正方法可应用于临床患者的头颈部肿瘤剂量计算。

Objective To establish a fast calibration method of CBCT HU value,and to apply it to the dose calculation of intensity modulated radiotherapy in actual patients.Methods The head and neck treatment plans of ten cases were taken to obtain CT images and CBCT images of the first treatment.Eclipse planning system was used for registration,and the contour structure outlined on CT image was copied to CBCT image.The average HU values of each contour on CBCT and CT were counted,and the HUCBCT-UCT curve was established to obtain the CT value-electron density curve corresponding to CBCT.Another 5 cases of head and neck were selected to calculate the dose before and after CBCT image correction,and Gamma consistency and DVH were compared between the dose distribution of CBCT and planned CT.Results The revised CBCT dose was consistent with CT dose.The Gamma consistency test results increased by 4.4%,and the average dose difference of PTV was less than 0.56%.Conclusion The CBCT HU correction method in this paper can be used to calculate the dose of head and neck tumors in clinical patients.