I need to use Screen Protractor to measure angles on x-rays of the legs. For example, we draw a line parallel to the knee joint, and another line from the center of the knee to the center of the hip, and need to measure that angle. In most of the x-rays that get sent to me by email from colleagues, I am looking at them as jpegs, and I don't have line tools to draw these lines. It would be helpful if the Screen Protractor had extended lines that did NOT end at the center of the circle, but rather EXTENDED beyond somewhat, so that I could use them to draw the knee line, and position the center of the PROTRACTOR  at the center of the knee.