Objective:To evaluate the cumulative dose of the target volume and organs at risk (OARs) in intensity-modulated radiation therapy (IMRT) for large volume non-small cell lung cancer (NSCLC) based on rigid and deformation registration methods. The dosimetric changes between the initial and second treatment plans were compared.Methods:Thirty patients treated with IMRT for large volume NSCLC with twice 4DCT scans acquired before radiotherapy and after 20 fractions of radiotherapy were recruited. The initial treatment plan (Plan 1) based on the average density projection CT (CT 1-avg) of the first 4DCT images and the second treatment plan (Plan 2) based on the average density projection CT (CT 2-avg) of the second 4DCT images were calculated. Then, the dose distributions of Plan 1 and Plan 2 were accumulated based on rigid and deformation registration methods to obtain Planrig and Plandef, respectively. Finally, the volume changes of gross tumor volume (GTV) and OARs between two CT scans were compared. The dose-volume parameters between Plan 1 and other plans (including Plan 2, Planrig and Plandef) were also statistically compared. Results:Compared with the initial CT scan, the mean volume of GTV and heart on the second CT was decreased by 44.2% and 5.5%, respectively, while the mean volume of ipsilateral lung, contralateral lung and total lung was increased by 5.2%, 6.2% and 5.8%, respectively (all P<0.05). Compared with Plan 1, the D 95%, D 98% and V 100% of target volume IGTV (GTV fusion of 10 4DCT phases) and PTV in Plan 2 did not significantly change (all P>0.05), and those in Planrig and Plandef were decreased (all P<0.05). The dose-volume parameters of spinal-cord, heart, ipsilateral lung and total lung in Plan 2, Planrig and Plandef were significantly lower than those in Plan 1(all P<0.05). Among them, the V 30Gy and D mean of heart were decreased by 27.3%, 16.5%, 15.3% and 15.2%, 6.6%, 5.6%, respectively. The V 20Gy and D mean of total lung were decreased by 15.6%, 4.5%, 3.7% and 15.7%, 6.2%, 5.1%, respectively. Some dose-volume parameters (including D 95% and D 98% of target volume, V 40Gy of heart, V 20Gy and D mean of the ipsilateral lung and the total lung) of Plandef were higher than those in Planrig (all P<0.05). The Dice similarity coefficients (DSCs) of OARs after deformation registration were significantly higher than those after rigid registration ( P<0.05). Conclusions:The dose-volume parameters of OARs significantly differ between Plan 1 and Plan 2. Hence, all these parameters have a large degree of deviation in predicting radiation-induced injury of OARs. Nevertheless, the dose-volume parameters obtained by deformation registration can enhance the prediction accuracy.

目的 在鼻咽癌调强放疗过程中,靶区和危及器官的体积不断变化,可能导致其实际接受剂量与初次计划剂量不一致.本研究通过形变配准方法获得2次计划的累积剂量,为预测鼻咽癌调强放疗的治疗反应提供参考.方法 收集2014-07-08-2018-05-02山东省肿瘤医院放疗科收治的18例进行同步加量调强放疗的鼻咽癌患者,在定位图像CT1上制定初次放疗计划Plan1,在治疗20～25分次后的复位图像CT2上制定放疗计划Plan2.利用Velocity将Plan2剂量与Plan1剂量分别刚性和形变配准累加得到Plan刚性和Plan形变.比较靶区和危及器官在Plan1、Plan2、Plan刚性和Plan形￡的剂量-体积指标变化.结果 18例鼻咽癌患者CT1和CT2中大体肿瘤靶区(gross tumor volume,GTV)分别为(79.28±49.66)和(64.47±42.39) cm3,Z=-3.724,P＜0.001;左腮腺体积分别为(16.76士4.74)和(10.77士4.07) cm3,Z=-3.724,P＜0.001;右腮腺体积分别为(16.63士4.40)和(10.46±3.99) cm3,Z=-3.724,P＜0.001.形变配准左腮腺(t=5.158,P＜0.001)、右腮腺(t=7.808,P＜0.001)、左视神经(t=2.664,P=0.016)和脊髓(t=4.660,P＜0.001)相似指数与刚性配准比较,差异有统计学意义.Plan2与Plan1相比,左右腮腺的V30以及脑干、左右眼球、左右晶状体、左右视神经的Dmax均下降,平均下降17.0％～60.1％.Plan形￡与Plan1相比,GTV和肿瘤计划靶区(plangross tumor volume,PGTV)的Dmean、D99,腮腺Dmean以及眼球和视神经Dmax变化均＜5％.Plan刚性与Plan1相比,GTV和PGTV的Dmean、D95,腮腺Dmean、v30、D50以及眼球和视神经Dax变化均＜10％.结论 鼻咽癌调强放疗过程中,肿瘤靶区及腮腺体积缩小,形变累加后靶区和危及器官各项剂量-体积指标与初次计划基本相当,因此初次计划的剂量-体积指标可以预测放疗过程中的疗效和放射性损伤.

Objective:To provide a feasible method for the evaluation of cardiac function based on cardiac gated 4DCT, the radiomics technology combined with enhanced ECG gated 4DCT images were used to quantitatively analyze the changes of left ventricular CT radiomics characteristics in cardiac cycle.Methods:The enhanced ECG 4DCT images of 14 patients were reconstructed at intervals of 5% of cardiac cycle. The left ventricular muscle (LVM) and the contrast agent well filled area of left ventricular were delineated with a 13 mm diameter sphere (Cardiac Region of Interest, cardiac ROI) in a single phase. 3Dslicer software was used to extract 92 features of all the sketches, analyze the distribution of CT values on the cardiac ROI and LVM, and preliminarily screen the stable features based on the cardiac ROI (one-way ANOVA). The stable features were used to further screen LVM (one-way ANOVA) to get the difference features. Wilcoxon rank sum test was used to analyze the change of characteristics with heartbeat in the heartbeat cycle.Results:In the heartbeat cycle the mean CT values of cardiac cavity ROI in cardiac cavity changed less than that in LVM, with the change rates of 9.23% and 17.88%, respectively. There were 36 stable features with no significant difference in cardiac cavity ROI ( P>0.05). 20 of them were statistically significant ( F=1.641-6.206, P<0.05), and the average change rate was 98.63%, such as median (-103.96%) and mean (123.67%) of the first order matrix, gray level non uniformity (99.81%) of GLDM matrix and other changes reached more than 99%. The differences between the maximum and minimum values in different cardiac cycles were statistically significant ( Z=-3.921--3.173, P<0.05). Conclusions:With the combination of radiomics and enhanced ECG 4DCT image, the microscopic changes of CT image features in the cardiac cycle can be amplifed. A new method for the assessment of left ventricular function changes was provided. The features such as median, mean may have more application potential.

Objective To investigate the changes of accumulated dose in target area and organs at risk (OARs) for radiotherapy of left breast cancer by deformable and rigid image registration.Methods A total of 16 left breast cancer patients treated with 6 MV X-ray IMRT were analyzed retrospectively.All targets included the lymph node drainage area and the chest wall.All patients underwent simulation of the primary positioning and repositioning to obtain CT images.Primary and secondary treatment plans were developed using primary positioning CT (CT1) and repositioning CT (CT2),denoted as Plan1 and Plan2 respectively.The dose distribution of Plan2 was mapped to CT1 with rigid and deformable registration from CT2 to CT1 and then added to the dose distribution of Planl to obtain Plan-rigid and Plan-deform,respectively.The dosimetric differences between targets and the OARs of the four plans were compared.Results The CTV volume on CT2 was reduced by 6.64％ from that on CT1.The homogeneity index (HI)increased by 23.05％ after deformation-based accumulation.The Dice similarity coefficients (DSCs) of the heart,left lung and right lung were lower than those before deformable registration (0.94±0.01 vs.0.89± 0.05,0.96±0.01 vs.0.91±0.03,and 0.96±0.01 vs.0.92±0.03,respectively),and the differences were statistically significant (Z =-3.208,-3.533,-3.535,P ＜ 0.05).There were no significant differences in dose-volume indices of heart and left lung between Plan1 with other plans (P＞0.05),while the dose-volume indices in Plan-rigid were higher than that in Plan-deform.Conclusions Rigid registration is recommended in patients undergoing radical resection of left breast cancer with little change in the volume and dose-volume index of the target area and organs at risk.The dose-volume index of the initial intensity modulation plan can basically reflect the dose-volume statistics of both lungs and heart.