Study Of Influence Of Respiratory Movement On The Target Volume In 3DCRT Of Esophageal Carcinoma

Objective: Esophageal carcinoma is the most common cancer in China,accounting for more than 50 percent of patients aroud the world.Mortality of esophageal carcinoma ranks the fourth place in malignant tumor in China.Radiotherapy has always been the main treatment methods because most of patients suffered from the locally advanced stage of this disease. However,the 5-year local control rate was only 10% for patients treated at routine radiotherapy. Recent technologic advances in radiotherapy, such as the routine clinical use of three-dimensional conformal radiotherapy (3DCRT) ,have made high-dose radiation feasible in routine clinical practice. 3DCRT is a mode of precision radiation therapy which offers the prospect of improved locally control rate and survival rate.But the potential dosimetric superiority of 3DCRT offers the advantage of better tumor target coverage and critical normal tissue sparing. But the delineation of the gross tumor volume and determination of clinical target volume were still to remain controversial; 3DCRT techniques on esophageal carcinoma are also needed to be further studied due to lacking mature expericnce in China and on abroad.In 3DCRT for esophageal carcinoma, the tumour position will change with the breath motion. This change is one important gist for confirming the scope of the internal target volume (ITV). How to confirm and control the scope of the affection moving with the breath motion, and nicely sketch the treatment target volume,not leave out the affection section when reducing the radiation to well organic around, have become to an important problem in current research. Recently, the several different methods that the scholar have bring forward which resolve the problem for confirming the ITV because of the breath motion are not very well.This study depend on three dimensional conformal treatment planning system (TPS) and image fusion, To observe the respiratory effects on 3DCRT of the esophageal carcinoma targets in order to obtain optimal values for ITV.Method: From December 2007 and December 2009,23 patients with Stage II to IIIa of esophageal carcinoma were obtained at the General Hospital of Armed Police Forces. 17 were squamous cell carcinoma (SCC) and 6 were adenocarcinoma (ADC),3 patients with upper esophageal carcinoma, 7 patients with middle esophageal carcinoma and 13 patients with lower esophageal carcinoma.All of the patients were performed the CT scanning in three levels: one acquisition in free breathing (FB), one at end expiration (EBH), and one at end inspiration (IBH).The scope of scanning must include all esophagus.The interval between two scanning is one minute at least in order to help the patient to resume the quiet breath rhythm. Results of all scans were transferred to the treatment planning system(TPS)and fused each other.Then outlined the gross tumor volume(GTV) and named the target in free breathing (GTVFB), and named the target at end expiration (GTVEBH), and named the target at end inspiration (GTVIBH). Measuring esophageal cancer in the Y axis, X axis, Z axis length and record data.The motion of tumor and disphragmatic muscle were measured between two point which was markd by the target center of GTV for each respiratory level. Respectively, whichever is greater moving distance for esophageal cancer.Statistical analysis using SPSS13.0 software.Result:The target center of GTV had some deviations along X,Y,Z axis. The deviation In 10 patients with upper&middle esophageal carcinoma were:Y axis (0.46±0.14)cm,X axis (0.52±0.26)cm,Z axis (0.59±0.26)cm;The deviation In 13 patients with lower esophageal carcinoma were :Y axis (1.17±0.69) cm,X axis (0.95±0.73)cm,Z axis (0.82±0.35)cm. Regression analysis showed that the movement distance of esophageal cancer target area lesion size and lesion-related.Conclusion: The GTV geometrical center of esophageal carcinoma had some deviations along X,Y,Z axis. Lower esophageal target volume in the Y axis, X axis, Z axis movement and lesion size. Shows the degree of respiratory movement in patients with esophageal carcinoma developing within the target volume (ITV) of the impact with statistical significance. In patients with esophageal cancer radiotherapy target volume should give full consideration to determine the location and size of the lesion.This study succeed to collecting the scan image which in the end of the inspiration and the exhalation when the patient locating on the quietly breathing state, and measured the motion by image fusion technique in the radiotherapy plan system, This method is so precise to obtain the numerus of ITV margin,then recommend to confirm the individualized ITV for every patient use this method.