Radiosurgery of multiple brain metastases with single-isocenter dynamic conformal arcs (SIDCA)

Abstract

PurposeTo propose single-isocenter dynamic conformal arcs (SIDCA), a novel technique for radiosurgery of multiple brain metastases, and to compare SIDCA with volumetric modulated arc therapy (VMAT) and multiple-isocenter dynamic conformal arcs (MIDCA) for plan quality. Methods and materialsSIDCA, MIDCA, and VMAT plans were created on 6 patients with 3–5 metastases. Plans were evaluated using Radiation Therapy Oncology Group conformity index (RCI), Paddick conformity index (PCI), gradient index (GI), volumes that received more than 100% (V100%), 50% (V50%), 25% (V25%) and 10% (V10%) of prescription dose, total monitor units (MUs), and delivery time (DT). ResultsSIDCA achieved conformal plans (RCI=1.38±0.12, PCI=0.72±0.06) with steep dose fall-off (GI=3.97±0.51). MIDCA plans had comparable plan quality and MUs as SIDCA, but 52% longer DT. The VMAT plans had better conformity (RCI=1.15±0.09, p<0.01 and PCI=0.86±0.06, p<0.01) than SIDCA, worse GI (4.34±0.46, p<0.01), higher V25% (p=0.05) and V10% (p=0.02), 49% less MUs and 46% shorter DT. ConclusionsAll three techniques achieved conformal plans with steep dose fall-off from targets. SIDCA plans had similar plan quality as MIDCA but more efficient to delivery. SIDCA plans had lower peripheral dose spread than VMAT; VMAT plans had better conformity and faster delivery time than SIDCA.