Radiosurgery can be delivered through a variety of modalities including robotic and fixed gantry linacbased systems. They appear equally effective and safe. Thus, community need and costs remain the main determinants for choosing a given modality. We performed an economic evaluation to identify settings in which one modality could be preferred over the other.

Using local estimates of resource volumes and unit prices, we computed the incremental cost/patient of robotic radiosurgery compared to fixed-gantry radiosurgery from a payer's perspective. By varying parameters of resource volumes, we performed a probabilistic analysis stratified by number of brain lesions. in addition, we performed sensitivity analyses to examine the effect of patient volume on cost/patient.

The cost of robotic radiosurgery was $4,783/patient, and cost of fixed-gantry radiosurgery was $5,166/patient. The mean incremental cost was $-383 (95% interval: $-670, $110) for all lesions, $78 ($23, $123) for solitary lesions, and $-610 ($-679, $-534) for multiple lesions. The cost/patient of robotic radiosurgery varied from $5,656 (low volume setting) to $4,492 (high volume setting).

in settings of moderate to high volume (6-10 hours of daily operation), and in multiple lesions, robotic radiosurgery is more cost effective than fixed-gantry radiosurgery.