ABSTRACT
Objective Compared with chest CT,endoscopic ultrasonography (EUS) can more accurately determine the upper and lower margins of esophageal cancer,and marking the upper and lower margins of the esophageal cancer with titanium clip contributes to the delineation of target area of esophageal cancer during radiotherapy.To compare the effects of esophageal X-ray,chest computed tomography (CT)scan and EUS-assisted placement of marker clip in the determination of the length of gross target volume (GTV),aiming to provide reference for the determination of GTV during esophageal cancer radiotherapy.Methods Thirty patients who were initially diagnosed with thoracic esophageal cancer by histological and cytological examinations and scheduled to receive radiotherapy were recruited in this investigation.All patients received esophageal X-ray,CT scan,and EUS-assisted placement of marker clip.The length of GTV was quantitatively measured and statistically compared among three different methods.Results The length of GTV was (6.1 ± 1.4) cm,(6.8± 1.9) cm and (6.3± 1.9) cm determined by esophageal X-ray,CT scan and EUS-assisted placement of marker clip,respectively.Compared with CT scan,the length of GTV determined by EUS-assisted placement of marker clip did not significantly differ (P=0.11).The length of GTV determined by esophageal X-ray was significantly shorter than that by CT scan (P =0.03).Among all patients,the length of GTV determined by EUS-assisted placement of marker clip was longer compared with that by chest CT scan in 22.2％ of patients.The length of GTV determined by EUS-assisted placement of marker clip was the same as that by chest CT scan in 11.1％ of patients.The length of GTV determined by EUS-assisted placement of marker clip was shorter compared with that by chest CT scan in 66.7％ of patients.Conclusions EUS-assisted placement of marker clip differs from esophageal X-ray and CT scan in determining the length of GTV,which acts as one of the effective methods in the determination of the length of GTV during esophageal cancer radiotherapy.