Yes I had a Pet Scan for cancer and yes you go in a tube but its very quiet and I closed my eyes and tried to think of the ocean in Hawaii, haha. It made me relax and then I realized that it was just a strange place to be but painless. I did have an IV for the chemical that has to be used to get the images but the nurse was very skilled and I didn't hardly feel anything. Just put your mind in a good place and it should be fine! My Pet Scan was also from the neck down. The machine moves back and forth a few times but it's a SMOOTH ride!