Optimization of hybrid treatment technique in radiotherapy treatment of different anatomic regions

In this study, new Hybrid Arc techniques were developed by applying two of the three techniques (Three-Dimensional Conformal Radiotherapy (3D-CRT), Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT)) used in radiotherapy clinics. Hybrid Arc techniques were planned by including the two different techniques in the optimization process in the treatment planning system. The results obtained from Hybrid Arc techniques for lung, prostate, and rectum treatment regions were compared with homogeneity index (HI), conformity index (CI), mean doses in the target region, maximum doses in the target region and critical organ doses of IMRT and VMAT techniques. In addition, the total treatment times (TTS) and monitor unit (MU) values of the three techniques were compared. For the lung target region; it was showed that Hybrid Arc technique was a fast, conformal and homogeneous technique compared to IMRT. Using Hybrid Arc technique, V5Gy and V10Gy values of the total lung, which caused the limited use of VMAT technique, were reduced to 8% and 4%, respectively. For prostate target region; Hybrid Arc technique compare with VMAT technique, the V75Gy value of the rectum was reduced to 51% and D%50 value of the bladder was reduced to 26%. Using Hybrid Arc technique, the value of MU was reduced to 5% and the value of TTS to 34% according to IMRT technique. For rectum target region; Hybrid Arc technique compared with VMAT technique, the V15Gy value of the intestine was reduced to 49% and V25Gy value of the bladder was reduced to 34%. Using Hybrid Arc technique, the value of MU was reduced to 17% and the value of TTS was reduced to 36% according to IMRT technique. It has been shown that, without increasing MU and TTS values, it is possible to decrease critical organ doses and increase homogeneity and conformity in target volumes with Hybrid Arc techniques.