How Many Images Are In An Upper Gi Series- On Mine It Was 12 Please Read Below?

I have read that an upper gi series (barium swallow) is usually around 24 images. When I had that test, I noticed that there were 12 images. . Would the typical amound of films on this test be 24 or 12 pictures? If so, would the radiation dose on mine have been cut and half? I have also found that the dosage of radiation on this film is 2 mSv. Would mine be 1 msv instead?