Set 4: cardiothoracic ratio-

the easy way

There is an easier way to do this.  If you find the widest point along the right side of the heart and  measure to the midline (the red line segment), you can then compare that to the distance from the widest point on the left and the inner left margin of the ribcage.  These line segments are MUCH easier to visually inspect and determine which is longer, without having to do any calculations.  As long as the red segment is equal to or shorter than the blue, then the cardiothoracic ratio is normal, as in this patient.  You are doing the exact same calculation as the standard method, but because the segments are shorter, it is easier and quicker to compare them visually.