Clinical Application Of Off-line Adaptive Radiotherapy In Esophageal Carcinoma

Objective:Having collected CT images of each patient before the first time radiotherapy, after the eighth time radiotherapy and after the sixteenth time radiotherapy, and having made three groups therapy plans, respectively named P1, P2 and P3. Comparing and observing the differences of volume and dosimetry of planning target volume(PTV), and the differences of dosimetry of organ at risk(OAR)in the three groups plans, this thesis had studied the clinical significance of the application of the off-line adaptive radiotherapy on the esophageal cancer patients.Methods:This study had taken six esophageal cancer patients, without being treated by any surgery. We collected CT images of each patient before the first time radiotherapy, after the eighth time radiotherapy and after the sixteenth time radiotherapy by large aperture CT of Artiste system of SIEMENS. Then drawn GTV-ex and GTV-nd, PTV1 and PTV2, double lung, spinal cord, hart and OAR on Pinnacle3 9.2 of Philips and named P1, P2 and P3.That all is a whole planning of ART. The fractionated dose of PTV1 and PTV2 was 2.13 Gy, 1.86 Gy, a total of 30 times, the total dose was 63.9 Gy, 55.8 Gy. The correlation parameters were corrected statistically. We compared the dose difference between the target area and OAR in the 3 plans combined with the dose statistical tables and dose volume histograms(DVH). All data were statistical analysed by SPSS 17 statistical software.Results:(1)In the 3 plans, the volumes of each patient before the first time radiotherapy, after the eighth time radiotherapy and after the sixteenth time radiotherapy are V1、V2、V3, there was no statistical significance(P>0.05)2(2)In the 3 plans, there were no statistical significance in the maximum,minimum and average dose of PTV, there are no statistical significance in homogeneity index and conformity index(P>0.05) as well. But, the Dmean showed a increasing trend and approached to the dose of 64 Gy. the figure of the CI had a increasing tendency and approached to 1.(3)There was no statistical significance in V40 of heart(P>0.05). There were also no statistical significance in V5、V10、V20、V30 of double lung and Dmean of spinal cord(P>0.05). However, there was some statistical significance in Dmax of spinal cords(P<0.05). OAR dose has not exceed the limit of clinical dose.Conclusions:(1)Off-line adaptive radiotherapy for esophageal cancer has little effect on the dose and volume of tumor target area. After 2 times modified plan, the target area could be more close to the planned dose, and the suitable shape of the target area was better, and the spinal cord was better protected.(2)Comparing the plan P1 and P2, P1 and P3, P2 and P3 parameters, we can guess, revising the treatment planning after the sixteenth radiotherapy may be have more clinical reference value.