Objective To explore the influence of different reconstruction modes with time⁃weighted respiratory phases on the internal tumor volume ( ITV) of solitary pulmonary lesion ( SPL) , and to evaluate the feasibilities of 8 and 4 equal time⁃weighted respiratory phases in 4DCT simulation. Methods 24 patients with SPL underwent 4D scanning. Images were reconstructed with 10, 8 and 4 equal time⁃weighted phases of the respiratory cycles, respectively. Gross tumor volumes ( GTVs ) were delineated on the three sets of reconstructed images and fused into ITVs, which were ITV10 , ITV8 and ITV4 respectively. The differences of volumes, centroid of the ITVs and motions of GTV centroids in three⁃dimensional directions were compared. Statistical analysis was performed using the Friedman M test. Results The volumes of ITV10 , ITV8 and ITV4 were (9.09±12�29) cm3,(9.10±12�47) cm3 and (8.98±12�61) cm3(P=0�001), respectively. There were no differences between the volumes of ITV10 and ITV8 after the Bonferroni correction ( P=0�721) , while the opposite between those of ITV10 and ITV4 ( P=0�002 ) . The differences of centroid positions of ITV10, ITV8 and ITV4 in x⁃, y⁃and z⁃axes were all less than 1 mm ((12.22±7�71),(12.23± 7�71),(12.22±7�71),Px =0�668);(43.30±29�38),(43.30±29�40),(43.31±29�39),Py =0�643;(5.66±3�67),(5.66±3�67),(5.66±3�67),Pz=0�878), similar to the motions of GTV centroids in three reconstructed modes ((0.69±0�56),(0.69±0�68),(0.79±0�51) mm,Px=0�356;(3.13±3�78),(3.13± 4�05),(3.19±4�06) mm,Py =0�978;(1.18±1�31),(1.03±1�32),(1.16±1�34) mm,Pz=0�302). Conclusions There were no differences in volumes, centroid positions and motions between ITV10 and ITV8 . The quantity of reconstruction images and GTV delineations according to 8 time⁃weighted phases were both less than conventional 10 phases. 8 time⁃weighted respiratory phases mode was feasible in 4DCT simulation for SPL.%目的：比较4DCT呼吸周期八分法、四分法与传统十分法重建模式对肺孤立灶靶区构建的影响，探讨八分法、四分法在4DCT模拟定位中的可行性。方法24例肺孤立灶行4DCT扫描，按3种呼吸周期均分法进行图像重建及ITV构建，比较ITV10、ITV8、ITV4大小和中心点位置及三维方向运动度。 Friedman M 法非参数检验差异。结果 ITV10、ITV8、ITV4大小分别为（9．09±12�29）、（9．10±12�47）、（8．98±12�61） cm3（P＝0�001），ITV10与ITV8相近（P＝0�721），ITV10与ITV4不同（P＝0�002）。 ITV10、ITV8、ITV4中心点坐标分别为x轴（12．22±7�71）、（12．23±7�71）、（12．22±7�71）（P＝0�668）；y轴：（43．30±29�38）、（43．30±29�40）、（43．31±29�39）（P＝0�643）；z轴：（5．66±3�67）、（5．66±3�67）、（5．66±3�67）（P＝0�878）。3种重建模式下肿瘤中心在三维方向的运动度分别为x轴：（0．69±0�56）、（0．69±0�68）、（0．79±0�51） mm （P＝0�356）；y轴：（3．13±3�78）、（3．13±4�05）、（3．19±4�06） mm （P＝0�978）；z轴：（1．18±1�31）、（1．03±1�32）、（1．16±1�34） mm （P＝0�302）。结论肺孤立灶4DCT模拟定位呼吸周期八分法与十分法重建模式下ITV大小、中心点位置及三维方向的运动度均相近，八分法减少了重建图像的数量和靶区勾画负荷，在4DCT模拟定位中具有可行性。
展开▼
