A comparison of gross tumor volume among three-dimensional, four-dimensional and cone beam computed tomography in primary esophageal cancer / 中华放射医学与防护杂志

ABSTRACT

Objective To analyze the volume and position of the gross tumor volumes (GTV) in primary esophageal cancer based on contrast-enhanced three-dimensional (3D),four-dimensional (4D) and cone beam (CB) computed tomography (CT).Methods A total of thirty-four patients underwent 3D-CT and 4D-CT simulation scans for computer treatment plan and contrast-enhanced CBCT scans were conducted prior to the first treatment.GTV3D,GTV4D50,internal GTVMIP (IGTVMIP) and internal GTVCBCT (IGTVCBCT) were delineated on 3D-CT,4D-CT50 (the end expiratory phase),4D-CTMIP (the maximum intensity projection),and CBCT datasets,respectively.The IGTV10 was defined as 10 respiratory phases GTVs in 4D-CT.To evaluate the difference in position,volume and the volumes encompassed characteristic.Results The significant difference was observed in the volumes [IGTV10 ＞ (IGTVCBCT or IGTVMIP) ＞ (GTV3D or GTV4D50)] regardless of the tumor location.Regarding IGTV10 as the standard volume,the underestimations or overestimations between IGTV10 and IGTVCBCT were larger than that of between IGTV10 and JGTVMIP (t =-8.294--3.192,P ＜ 0.05).However,there was no significant difference between the areas of IGTV10 which excluded in IGTVCBCT and IGTV3D (P ＞ 0.05).The GTV4D50/ IGTVCBCT ratio for upper esophageal tumors was negatively correlated to motion vector (r =-0.756,P ＜ 0.05).The centroid coordinates of IGTVCBCT in AP direction were significantly different from the test volumes (GTV3D,GTV4D50,IGTVMIP and IGTV10) (t =-3.559--2.435,P ＜ 0.05).The IGTV10/IGTVCBCT ratio was positively correlated to motion vector (r =0.695,P ＜ 0.05) for middle esophageal tumors.The centroid coordinates of IGTVCBCT were significantly different IGTV10 (t =2.201,P ＜0.05) in AP direction.For distal esophageal tumors,the significant difference was observed in the centroid coordinate between IGTVcBcT and IGTVMIP (t =-2.365,P ＜ 0.05) in LR direction.The percentage of IGTV10 excluded the IGTVcBcT were significantly correlated to the motion vector (r =0.540,0.678,P ＜ 0.05) for both middle and distal esophageal tumors.The mean MI value of IGTVCBCT to the other four test volumes ranged from 0.65 to 0.72.Conclusions CBCT has much motion information than 3D-CT but less than IGTV10.CBCT was similar to MIP images based on respiration motion.However,the target motion information encompassed in CBCT and MIP images cannot be exchanged to each other.