Dose-volume effect in gamma knife radiosurgery of meningiomas

Objective: To study the relationship between dose-volume effect and complication in gamma knife radiosurgery of intracranial meningiomas. Method: By using an integrated logistic formula to establish mathematical models, the authors analyzed the relationship between treatment volume and logistic probability for 15 Gy, and the relationship between prescribed dose and treatment volume in 3% logistic probability. Furthermore, 37 meningiomas treated by gamma knife radiosurgery were analyzed retrospectively to investigate how the 3% isoeffect curve impacted on complication. Result: There was a linear relation between treatment volume and logistic probability for 15 Gy. The regression formula was f(x) = 0.0042x + 0.0007. The 3% isoeffect curve indicated that the prescribed dose was inversely proportional to the treatment volume. During 16.3 months followup on average, 18 cases below the 3% isodose curve were without complication, but in 19 cases above the 3% isodose curve, 5 cases suffered complications, the difference being statistically significant. Conclusion: Dose selection in gamma knife radiosurgery is volume dependent. The 3% isodose curve may possibly be the guideline in gamma knife radiosurgery of meningiomas. Copyright (C) 2000 S. Karger AG, Basel.