1. A medical viewing system, comprising: an X-ray image acquisition device comprising a flat X-ray detector and an X-ray source, said source comprising a collimator; a display unit; and a calculation unit connected to said X-ray image acquisition device and said display unit, said collimator being adjustable such as to cause an X-ray image acquired by the X-ray detector from X-ray radiation collimated by said collimator to have a rectangular shape with rounded corners, the rounding being variable in accordance with the adjustment, wherein the calculation unit is configured for displaying the acquired image on the display unit, and by said displaying enclosing a variable gap between the borders of the image and the borders of the display unit such that the image is rotatable without intersecting the borders of the display unit.