Objective To analyze the changes of the volume and dose of target areas and organs-at-risk by comparing the cone beam CT (CBCT) images and planning CT images of patients with non-small cell lung cancer (NSCLC),and to accumulate the dose based on deformation registration,and finally to analyze the differences between planned dose and delivered dose.Methods The clinical data of 8 NSCLC patients receiving conformal radiotherapy or intensity-modulated radiotherapy (IMRT) were retrospectively analyzed.With the CBCT image of each week as target image,we performed the deformation registration for CBCT image and planning CT images in RayStation,and superposed the delivered dose of CBCT image to planning CT images with the use of mapping relationship in registration.The differences between planned dose and accumulative dose of target areas and organs-at-risk (including heart,spinal cord and lungs) were compared.Results At the last stage of treatment,the average gross target volume (GTV) in CBCT images was 88.28％ of the original volume.The average planned and accumulative dose of GTV in 8 patients were (1 166.49±645.42) and (1 150.13±630.27) cGy,respectively (P＜0.05).The average planning target volume (PTV) reaching the prescription dose in CT plans and accumulation plans was 95.59％ and 81.47％ of the PTV (P＞0.05).At the last stage of treatment,the volumes of the left and right lungs in CBCT images were 88.95％ and 80.32％ of the original volume.The left and right lungs in CT plan received an average dose of (167.31 ± 165.75) and (79.33±54.11) cGy,respectively,and an accumulative dose of (164.63±164.96) and (77.63±53.36) cGy,respectively (P＞0.05).The average and accumulative doseof heart was (61.88±66.70) and (68.38±60.91) cGy,respectively (P＞0.05).The average maximum dose and accumulative dosefor spinal cord was (372.62± 185.91) and (360.00± 173.14) cGy,respectively (P＞0.05).Conclusion With the dose deformationsuperposition method,the differences between planned dose and cumulative dose caused by the changes of anatomical structurein target areas in NSCLC patients can be found,providing a reference for adaptive radiotherapy.%目的:应用非小细胞肺癌患者锥形束CT(CBCT)图像和计划CT图像比较,分析在治疗过程中靶区及危及器官的体积和剂量学变化,并应用变形配准方法进行剂量叠加,分析计划剂量与实施剂量的差别.方法:通过回顾分析8例接受适形放疗或调强放疗的非小细胞肺癌患者,应用RayStation的变形配准功能将每周CBCT图像作为靶图像与计划CT进行变形配准,应用配准的映射关系分别将每周CBCT实施剂量叠加至计划CT,比较靶区和危及器官(心脏、脊髓、双肺等)计划剂量与累积剂量的差别.结果:8例患者大体肿瘤靶区在治疗末CBCT图像上显示的平均体积变化为原体积的88.28％.大体肿瘤耙区的计划剂量平均为(1 166.49士645.42) cGy,累积剂量平均为(1 150.13±630.27)cGy,两者比较,差异有统计学意义(P＜0.05).CT计划和累积计划的计划靶区达到处方剂量的体积(V100)平均分别为95.59％和81.47％ (P＞0.05).治疗末期,CBCT图像中左右肺的体积平均变化分别为原体积的88.95％和80.32％.左右肺CT计划平均剂量分别为(167.31±165.75)和(79.33±54.11)cGy,累加剂量平均为(164.63±164.96)和(77.63±53.36)cGy,差异无统计学意义.心脏的平均剂量为(61.88±66.70)cGy,累积剂量平均为(68.38±60.91) cGy,差异无统计学意义.脊髓的最大剂量平均为(372.62±185.91)cGy,累积最大剂量平均为(360.00±173.14) cGy,差异无统计学意义.结论:非小细胞肺癌患者靶区解剖结构的变化使计划剂量与实施剂量存在差别,应用剂量变形叠加的方法可发现计划与实施剂量的差距,为自适应放疗提供参考.
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