This system is a computer-based system for simulating an effect of a specific surgical treatment method based on three dimensional shape data of a target vascular site of a subject, comprising: a treatment method receiving unit, by a computer, for displaying the three-dimensional shape data of a target vascular site on a computer display screen, and receiving a specification of a lesion on display and a selection of a surgical treatment method for the lesion, a modification method storage unit, by a computer, for pre-storing selectable treatment methods and methods for modifying the three-dimensional shape data for respective treatment methods in memory, and a modified three-dimensional shape data output unit, by a computer, for reading out a modification method from the modification method storage unit according to the selection of a treatment method, modifying the there-dimensional shape data related to the specification of the lesion by the selected method, and outputting the modified three-dimensional shape data.
