Comparison of cyberknife and gammaknife treatment plans for target volume and normal tissue doses

Stereotactic radiosurgery (SRS) is a highly precise form of radiation therapy initially developed to treat small intracranial lesions. The goal is to deliver doses that will destroy the tumor and achieve permanent local control.Intracranial SRS can be done in an excellent way with dedicated machines. Gamma Knife and Cyberknife are two of these dedicated machines for this approach.In this study, SRS planning was performed to 11 intracranial metastases of 9 patients with the two dedicated treatment planning system. The dose volume histograms and dosimetric parameters were compared. Those parameters included heterogenity index (HI), conformality index (CI), gradient index (GI), volume of the normal brain receiving 8Gy (V8), 10 Gy (V10) and 12 Gy (V12) .The mean RTOG CI of the CK and GK treatment plans were 1.14±0,07 and 1.16±0.17 respectively where the mean Paddick CI was 0,82 ± 0,04 and 0,85 ± 0,10 (0.64-0.95) (NS). The mean GI of the CK and GK treatment plans were 3,26 ± 0,47 and 3.05±0.51 respectively (NS). GK plans were more heterogeneous than CK plans with a HI 1.98 ± 0.19 vs 1.09 ± 0,05 (p=0.003). V8, V10 and V12 values of the normal brain were not found to be different in the two treatment planning systems.GK and CK treatment planning systems are two excellent tools for stereotactic radiosurgery of solitary intracranial lesions in terms of universal dosimetric parameters.