Comparison of dose distrubution for critical organs with intensitiy modulated radiation therapy and 3D conformal radiotherapy for gastric cancer

In this study four field 3 dimensional conformal radiotherapy technique (3DCRT) and seven field intensity modulated radiation therapy (IMRT) techniques were compared due to determine to superiority between the treatment planning tecniques in clinical use for 10 patients with gastric cancer who had surgery. Computed tomography simulation was performed supine positions, and the images of the patients were transfered by Digital Imaging and Communications in Medicine (DICOM) to Oncentra 4.3 treatment planning system (TPS). 3DCRT planning were performed by using four field technique. The total dose of 50.4 Gy (1.8 Gy/fraction) were delivered to 95% isodose of Planning Target Volume (PTV). Target drawn on the same volume without changing the planning system Oncentra 4.3 transferred to Monaco 5.0 IMRT planning system plans were created. 6 MV photon energy and seven field techniques were used with Monaco 5.0 planning system. The analyses of doses of the target volume and critical organs were performed. As a result when 3DCRT and IMRT techniques were compared according to the 95% of PTV exposed to the dose; the plans made by IMRT technique were no statistically significant difference between 3DCRT seven field IMRT technique (p=0.909). When we compared the whole planning techniques according to the percentage of liver volume exposed to 30 Gy and more; between 3DCRT and seven field planning technique is found to be statistically significant (p=0.001). As the planning techniques according to the percentage of spinal cord volume receiving the dose of 30 Gy and more were analyzed there was a significant difference between 3DCRT and IMRT (p=0.001), the seven field IMRT technique was found more statically significant than 3DCRT. When we look at the result of istatistical means, we observe that percentage absorbtion volume of all critical organs decresed as percentage dose in seven field IMRT technique. Considering the clinical intensity, abdominal radiation therapy (RT) treatment is to beter protect critical organs in patients with IMRT is recommended.