I notice that the discussion of dental X-rays has been in terms of using
film as the recording medium. My high-tech Italian dentist puts a little
boxlike solid-state imaging device in my mouth, and after an X-ray flash
immediately shows me the tooth on a crt monitor mounted above the tray with
all the nasty instruments. He plays with the contrast and brightness to
look at different parts of the tooth. He tells me that the exposure needed
to record the image with this technology is significantly lower than that
needed with film.