A thyroid collar is an act of care that photographs badly. In a rotating panoramic beam, the very material that stops the dose can cast a ghost across the jaw - and the guidelines have begun to ask whether the protection was worth the picture...
We are trained to fear the dose. We are rarely trained to fear the missed diagnosis. A cone-beam scan is a decision between two risks, not one - and the picture that goes unmade has a cost of its own....
Film punished overexposure by going dark. Digital rewards it with a cleaner picture - which is exactly how dose creeps upward, invisibly. Here is the number that fixes it....
A radiograph's contrast is built by the photons that are cleanly absorbed and the ones that pass straight through. The scattered photon belongs to neither, and it is the quiet vandal of the image - a fog with no source that dental imaging fights not...