Dosimetric Comparison Of CT And X-ray Simulation In Course Of Radiotherapy To Lung Cancer

Objective: To compare radiotherapy plans of X-ray Conventional simulation with CT simulation by using the Cadplan 6.4.7 treatment planning system.Methods: Thirty- three patients were recruited to conduct with both X-ray Conventional simulation and CT simulation in the same treatment position. 4-field conventional plan (RT),4-field two dimensional plan(2D)and three dimensional conformal radiation plan(3DCRT)were designed for each of 33 patients by using the Cadplan 6.4.7 treatment planning system. The prescription normalized dose was 50 Gy. DVH was employed to evaluate the differences with target coverage, dose distribution and normal tissue protection for each of plans. Result: (1)3DCRT and 2D based on the CT simulation were superior to RT in the target coverage,target conformity index(TCI)and target homogeneity (TH)(P<0.05).(2)the TCI and TH of 3DCRT were significantly higher than that of 2D(P<0.05)plans. No statistically differences were observed between the 3DCRT and 2D plans for the target volume enclosed by the 90% isodose and doses delivered to 90% target volume.(3)Compared to RT and 2D, 3DCRT decreased The volume of normal lung and heart tissue covered by the 90% isodose. V20, V30and MLD show the similar trend in the3DCRT,2D and RT plans. Moreover, (4)The maximum doses of spinal cord among the three different kinds of plans were significantly different. No statistical difference with doses to 30% of heart volume and esophagus tract among three plans were observed. Conclusion: There...