COMPRASION OF DOSE DISTRIBUTION FOR CRITICAL ORGANS WITH INTENSITY MODULATED RADIOTHERAPY AND 3D CONFORMAL RADIOTHERAPY FOR GASTRIC CANCER

Objective: Early and late complication may occur depending on the radiation dose in patients receiving gastric radiotherapy (RT), especially in the liver and kidneys. With the development of modern RT techniques, many planning techniques have been developed to reduce side effects. This study compared 3-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiation therapy (IMRT) planning techniques to determine which is superior in clinical use for postoperative planning of gastric cancer patients.
Material and Method: The target volumes drawn on Oncentra 4.3 planning system for 3DCRT were transferred to Monaco 5.0 IMRT planning system without any change. The total dose of 50.4 Gy (1.8 Gy/fraction) was delivered to 95% isodose of planning target volume (PTV). The analyses of doses of the target volumes and critical organs were performed. Independent-Samples T and Mann-Whitney U tests were used to compare the doses of PTV and critical organs in both techniques. P value <0.05 was considered statistically significant.
Results: When 3DCRT and IMRT techniques were compared according to the 95% isodose of PTV, a statistically significant difference was not found (p=0.909). Considering % doses of liver and spinal cord exposed to 30 Gy and more in both planning techniques; the IMRT technique was found to be statistically superior to 3DCRT (p<0.05).
Conclusion: IMRT is recommended to protect critical organs better for gastric cancer patients receiving abdominal radiotherapy.