Dosimetric and Biological Outcomes of Gamma Knife Radiosurgery and Volumetric Modulated Arc Therapy

Introduction: This research aimed to evaluate the radiation-induced secondary cancer risks in normal tissues following Gamma Knife Radiosurgery (GKR) compared with the Volumetric-Modulated Arc Therapy (VMAT).Material and Methods: Eleven patients with meningioma (2 males, 9 females; median age 30 years) were analyzed. For each case, Gamma Knife radiosurgery (GKR) and volumetric modulated arc therapy (VMAT) plans were created and compared using dosimetric-metrics and radiobiological modeling. The Organ Equivalent Dose (OED) was estimated using linear, linear-exponential, and plateau dose–response models, and the Excess Absolute Risk (EAR) was calculated for organs at risk to estimate secondary cancer risk.Results: Dose coverage, conformity, and homogeneity in the Planning Target Volume (PTV) improved significantly ('p'< 0.05) with GKR and VMAT. Higher OED was observed in the optic nerve due to proximity to the target. While the EAR of the optic nerve increased by 11.23%, 13.17%, and 14.86% in GK compared to VMAT for the linear, plateau, as well as linear-exponential models, respectively, in GK plans compared to VMAT, the EAR for the brain stem increased by 54.4%, 17.14%, and 30% in VMAT. GKR had a considerably greater Tumor Control Probability (TCP) (95.76%±2.86) than VMAT (84.29%± 2.27, 'p'= 2.8×10-6).Conclusion: GKR provided better PTV dose coverage and conformity, whereas VMAT achieved superior dose homogeneity. According to EAR, VMAT had a greater second cancer risk than GK. For young patients, advanced radiotherapy techniques should be evaluated in consideration of dosimetric, radiobiological, and secondary cancer risks.