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 (۲ males, ۹ females; median age ۳۰ 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'< ۰.۰۵) 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 ۱۱.۲۳%, ۱۳.۱۷%, and ۱۴.۸۶% 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 ۵۴.۴%, ۱۷.۱۴%, and ۳۰% in VMAT. GKR had a considerably greater Tumor Control Probability (TCP) (۹۵.۷۶%±۲.۸۶) than VMAT (۸۴.۲۹%± ۲.۲۷, 'p'= ۲.۸×۱۰-۶). 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.

کلیدواژه ها:

Second cancer risk ، GKR ، VMAT ، TCP ، NTCP ، Meningioma