Investigation of dose optimization of stereotactic radiosurgery methods in multiple brain lesions

In this study, the dose optimization of stereotactic radiosurgery techniques was compared in the treatment of multiple brain lesions using different devices. For this purpose, treatment plans prepared using CyberKnife Radiosurgery, Helical Tomotherapy and Volumetric Modulated Arc Therapy (VMAT) techniques. The results were compared and evaluated according to their superiority to each other. 18 Gy doses were defined in a single fraction for each plan. All plans were normalized to deliver ≥%95 of the prescription dose to all lesions. The minimum, maximum, mean doses were investigated for critical organs and the volume of brain which received 8, 10, 12 Gy dose were analyzed. Additionally, CI, HI and MU calculated in each treatment plans. Some plans were statically different in terms of critical organ doses but the results were clinically acceptable. The mean values of V12 (cc) were found to be 12.6, 38.23, 37.46 for VMAT, Cyberknife and Tomotherapy, respectively when evaluating the doses taken by healthy brain tissue. It has been determined the VMAT technique provides the best protection. The mean values of CI were found to be 1.04±0.19, 1.38±016, 1.31 ± 0,26 for VMAT, Cyberknife and Tomotherapy, respectively. It has been founded the VMAT technique provides the best in terms of uniform dose distribution. The mean values of HI were found to be 1.21±0.06, 1.15±0.04, 1.08±0.02 for VMAT, Cyberknife and Tomotherapy, respectively. It has been founded the Tomotherapy provides the best in terms of homogeneous dose distribution. VMAT is more advantageous than other planning technic in terms of MU. Thus, the treatment time is shorter. As a result, there are acceptable results for target and critical organ doses in three different treatment device. Key Words: Stereotactic radiosurgery, multiple brain lesions, lineer accelerator, cyberknife, tomotheraphy