中文摘要：

目的 研究早期非小细胞肺癌（NSCLC）患者行立体定向放射治疗（SBRT）时,基于千伏级锥形束CT（kV-CBCT）和定位CT制定放疗计划的心脏受量的差异.方法 选取在本院接受放射治疗的早期NSCLC患者15例,每次治疗前均拍摄CBCT进行摆位误差纠正.利用每位患者前10次的CBCT进行研究,处方剂量定义为5 Gy×10次.应用首次kV-CBCT与定位CT进行心脏范围勾画,比较两种勾画方式下心脏剂量学参数的差异.结果 基于第1次治疗时的kV-CBCT图像勾画的心脏体积（717±103）cm3大于基于定位CT勾画的（588±90）cm3,差异具有统计学意义（t=13.8,P＜0.05）;基于kV-CBCT获得的心脏相对剂量-体积（VxGy-R）指标中除V5Gy-R外,V10Gy-R、V15Gy-R、V20Gy.R、V25Gy-R、V30Gy-R、V35Gy-R大于基于定位CT,差异有统计学意义（t=2.3 ～3.9,P＜0.05）;基于kV-CBCT所获得的绝对剂量-体积（VxGy-A）指标V5Gy-A、V10Gy-A、V15Gy-A、V20Gy-A、V25Gy-A、V30 Gy-A、V355 Gy-A大于基于定位CT,差异有统计学意义（t=4.8～7.9,P＜0.05）;基于CBCT所获得的心脏固定体积内的剂量指标D50cm3、D100cm3、D150cm3、D200cm3、D250cm3及Dmean、Dmax大于基于定位CT,差异有统计学意义（t=2.9 ～6.5,P＜0.05）.结论 根据kV-CBCT的特性及其心脏受量统计分析,应用kV-CBCT进行心脏受量评价可弥补心跳和呼吸的影响,得到更真实、客观的剂量-体积参数.

英文摘要：

Objective To compare the difference in evaluating the heart irradiation dose based on different heart range contoured on kilovohage-cone beam computed tomography（kV-CBCT）and planning CT images in stereotactic body radiotherapy（SBRT）of non-small cell lung cancer（NSCLC）at early stage.Methods Fifteen early NSCLC patients who underwent radiotherapy were selected.For every case,kV-CBCT scan was achieved before every fraction treatment to correct the setup error,and the first 10 serious kV-CBCT images were adopted.The heart range on kV-CBCT and planning CT images was contoured and the differences between volume and dose-volume indices were analyzed.Results The heart volume on first kV-CBCT[（717 ± 103）cm3]was larger than that on planning CT[（588 ± 90）cm3]with statistical difference（t=13.8,P〈0.05）.The relative dose-volume indices：V10Gy-R,V15Gy-R,V20Gy-R,V25Gy-R,V30Gy-R,V35Gy-R obtained on CBCT images were larger than those on planning CT with statistical difference（t=2.3-3.9,P〈0.05）expect for V5Gy-R.The absolute dose-volume indices：V5Gy-A,V10Gy-A,V15Gy-A,V20Gy-A,V25Gy-A,V30Gy-A,V35Gy.A obtained on CBCT images were larger than those on planning CT,and all differences were statistically significant（t=4.8-7.9,P〈0.05）.The dose of certain heart volume Dmean,Dmax,D50 cm3,D100 cm3,D150 cm3,D200 cm3,D250 cm3,based on CBCT images were larger than CT images with statistical difference（t=2.9-6.5,P〈0.05）.Conclusions Based on the characteristics of kV-CBCT and the dose-volume indices of heart,the more accurate and objective dose-volume indices could be obtained through applying kV-CBCT in SBRT of NSCLC. Keywords：Stereotactic body radiotherapy;Dosimetry;Kilovoltage-cone beam computed tomography;Heart