A comparison of the different CT scanning modes on the GTV delineation of the solitary pulmonary lesion

Objective: To 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). Results: GTVs 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 axes 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 4.96 cm (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). Conclusions: There 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. (authors)