If the 测量助手 is not selected as source of an ROI, a new ROI can be created and edited using the ROI menu buttons above the line profile display. Those buttons allow you to draw either a linear or a circular ROI, delete all ROIs or view the ROI shape. Once an ROI has been created with the Draw Line or Draw Circular Arc buttons, those ROI creation buttons are grayed out because the line profile window can only handle one ROI at a time.