okay so we're going to go over sacrum coccyx sacrum coccyx you're going to have a patient laying on the table supine we're going to use a 40 inch sid we want to ensure that our tube is in transverse content we're going to use a 10 by 12 cassette size or collimation because we have the 14 by 17 kissing size in there so we're going to line up our tube and bucky there make sure that we're set column 8 down to 10 by 12 lengthwise and then we want to make sure that we have an angle on our tube because of the angle of the sacrum in the body we want to match that so we're going to angle 15 degrees towards the nose for the ap sacrum and then we angle 10 degrees towards the toes for the ap coccyx so i'm gonna feel on her side here and find her as is um the central breakpoint technically is two inches superior to the symphysis pubis but because we don't palpate that i find the as is and i go about two inches or three fingers inferior to that i want to make sure that i'm centered at the mid sagittal plane and you can do a couple things to check that you're centered properly find the top of the iliac crest and ensure that you have light to the top of the crest and then you can also have your patient bend their knees up slightly and use the crease of their leg to see where the symphysis pubis would lie i'm going to put my marker my right marker up here in the anterior corner of the cassette and then i would have my patient taken a breath blow it out and hold it out all right so then you can relax and then i'm going to angle down 10 degrees towards the tank toes for my coccyx realign my tube and bucky and i'm going to center in the exact same spot i know it sounds weird to center in the same place but because of the angle of the tube it's changing where you're actually your central ray's entering at so i want to be two inches superior to the symphysis pubis i'm going to collimate down the coccyx is only about the size of a quarter or posted stamp so we don't need much light i want to ensure that i'm still centered at the midsectional plane i can double check again by bending up the leg make sure that i'm two inches superior to the synthesis pubis and then i would just have my patient again taking a breath blow it out hold it out good you can breathe now what i'm going to have you do is roll onto your left side for me put both feet and hips right on top of each other both hands together in front of your face i'm going to take my angle off and realign my tube and bucky i want to make sure because i collimated down on the last one that i open it back up to a 10 by 12 lengthwise i'm going to ensure that my patient isn't rotated and then i'm going to find the as is and i'm going to center sorry center three to four inches posterior about four inches actually posterior to that directly posterior to the as is i can double check make sure here's my mid coronal plane i want to be at least one inch posterior to the mid coronal plane and then i'm going to check to make sure that i have the top of the sacrum on there so then i would have my patient just taking another breath blow it out and hold it out so that's it for the sake of practice