Role of Kilovoltage Cone-beam CT in Determining Individual Internal Target Volume for Lung Cancer Patients

ObjectiveTo assess the role of kilovoltage cone-beam CT (kVCBCT) in determining individual ITV for lung cancer patient. Methods Fourteen patients pathologically confirmed peripheral non-small cell lung cancer were entered into this study. One conventional planning CT and three kVCBCT scans were performed during quiet respiration for each patient.kVCBCT were all aligned to the conventional planning CT.After contouring GTV/IGTV, 5 mm margin was performed to generate CTV/ITV.The volume of ITV-p (generated from conventional planning CT) and ITV-c (generated from kVCBCT) were compared.Overlap volume of ITV-p and ITV-c were documented.The volume of CTV and ITV-c were compared with each other.The reproducibility of the kVCBCT was evaluated using the ratio of COM/SUM. Results The volume of ITV-p and ITV-c had statistics significant difference (P<0.0001).The overlap volume of ITV-p and ITV-c was 67.1 cc.The volume of CTV and ITV-c had statistics significant difference (P=0.005).The COM/SUM ratio of three ITVs which were defined from different kVCBCT scans was 63.0%±8.2%. Conclusion KVCBCT plays an important role in capturing the tumor movement and determine the individual ITV for lung cancer patient.