Selection method and selection system for dose control points, and radiotherapy planning system

The invention provides a selection method and a selection system for dose control points, and a radiotherapy planning system. The selection method for dose control points comprises the steps of among all interested regions, defining regions with the distances thereof from the edge of an image smaller than or equal to a preset distance as the marginal area and defining the rest region as the central area, sampling the center area at a center sampling rate, dividing the marginal area into multiple layers, sampling the multiple layers of the marginal area from the outermost layer to the inner most layer thereof at a gradually reduced sampling rate, and adding up all sampling points in the central area and all sampling points in the marginal area to obtain dose control points in the interested regions. According to the invention, the number of sampling points is not greatly increased, while the number of sampling points in the marginal area is increased. In this way, the dose over dose control points can be conveniently controlled and optimized.