A scope of medical treatment as an object of medical treatment is predetermined, and an image for treatment region considered as already completed treatment in the course of medical treatment is acquired.
Time up to completion of the whole scope of intended treatment regions is estimated on the basis of the already completed treatment region.
Further, any changes of sites under treatment are displayed by color indication.
Still further, the time up to completion of medical treatment is determined in a way easy to understand by simulating an image of treatment completion with respect to multiple treatment periods.
By virtue of these characteristics, not only can an improvement of medical treatment accuracy be attained but also the total time and exposure for medical treatment can be minimized.