Great, thank you. But I have a dubt. When we are at step 3 and probe is axial position , TP5 is in the middle of the screen. I have iliac crest on the right.... but why I have FJ S1-L5 and not L4-L5?. If I consider x-ray image the anterior leg of the scottie dog is inferior facet joint of L5 and it it below of the muzzle of the dog and not at same level. What I don't understand?