A method for forming a curved surface in a decorated board which enables a woodworking process to be easily performed on a peripheral edge of a curved decorated board. The protrusion weight can protrude from at least the heel portion of the head body. The threshold circuitry is configured to discard radiation hits on the pixel detector outside a predetermined threshold range, and the charge accumulation circuit is configured to accumulate charge directly resulting from a plurality of successive radiation hits on the respective pixel detector within the predetermined threshold range.