ABSTRACT
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.
ABSTRACT
ObjectiveTo explore the influence of the CT scanning mode on the gross tumor volume (GTV) delineation of solitary pulmonary lesion (SPL),and to evaluate the feasibility of the spiral CT scan in CT simulation.Methods Sixteen patients with SPL underwent axial scan,spiral scan during free breathing.Compare the target position,volume between GTVS and GTVA (paired t-test).The matching index (MI) between GTVS and GTVA and correlations between MI and the tumor volume were calculated ( bivariate correlation analysis).ResultsGTVS and GTVA volume was 8.95 cm3 and 9.38 cm3 ( t =0.43,P =0.667),respectively.The centroid position for GTVS and GTVA in x,y and z axises were 6.80 cm and 6.81 cm (t =0.27,P =0.794),36.19 cm and 36.05 cm (t =0.37,P =0.717),and 4.99 cm and 4.96cm (t =0.65,P =0.526),respectively.There were also no statistically significant difference in the distance between the centroidal position and origin of coordinates for GTVS and GTVA (38.31 cm∶ 38.23 cm,t =0.47,P =0.646 ).MI between GTVS and GTVA was 0.36 ( range 0-0.77 ),correlated with the tumor volume (r =0.587,P =0.017).ConclusionsThere was no significant difference between the axial scan and spiral scan in the GTV volume and position for SPL,but MI between GTVS and GTVA were small.A correlation was found for the MI between GTVS and GTVA with the tumor volume.Spiral CT scan was more timesaving,and was feasible in CT simulation scan.