In our opinion, ALL x-rays need to have a determined scale factor. Here's why:  We know that the anatomy in every image is GUARANTEED to be wrong in size.  Therefore every measurement that you make is GUARANTEED to be wrong and planning software can't remedy the situation without first scaling the image. The explanation is magnification and the topic is always the elephant in the room.   X-rays are deceptive.  BUT they don't have to be.  With an Akucal from J2 Medical, X-rays can be extremely accurate!  And that will make you extremely accurate as well because we calculate the actual size of the anatomy in an image by determining the magnification factor.  It's the fundamental necessity of radiology.