Comparison of dose distribution in different tumor volumes by using intensity modulated radiation therapy and three-dimensional conformal radiotherapy techniques for glioblastome multiforme treatment

In this study, three dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiation therapy techniques were compared within the field in field (FIF) and inverse planning techniques in terms of target coverage, dose of critical organ and the health brain lobe in different tumor volume. Three groups were formed according to the PTV60 treatment volume defined on the tomography images of 19 patients with GBM. Target volumes were defined on tomography images using magnetic resonance images for all patients. PTV50 and PTV60 target volumes of all patients have applied 3BKRT, FIF and inverse planning techniques with 6MV photon energy as daily fraction doses 2Gy. The minimum, maximum and mean doses of target volumes and critical organs and also V40, V50, V60 doses of health brain lobes were examined. When 3BKRT, FIF and Inverse planning techniques are compared according to different tumor volumes and received doses of target volumes and critic organs, there is no significant relationship between applied technique and volume. When the mean and maximum doses of brainstem were compared between the three techniques, the inverse planning technique was found significantly lower than the other techniques and it has been seen that different volumes affect the result significantly. The percentage mean doses of all critical organs were found to be lower in the inverse planning techniques for percentage volume doses. When 3BKRT and Inverse planning techniques are compared according to received V40, V50, V60 doses of brainstem, the inverse planning technique has shown to better protect the healthy brain lobe. When the size of the tumor volume increases, the received dose of health brain lobe is increased in the treatment of patients with GBM. The inverse planning technique has better protection of critical organs and conformity of target volume. In order to reduce the risk of late radiation necrosis in the brain lobe, using of intensity-modulated radiotherapy techniques is recommended in the radiotherapy of patients with GBM, taking account of the clinical possibilities.