CHAPTER 2

CHAPTER 2

1. CR compensation for cephalic and caudal angles

   • For deep anatomy, any caudally-angled beam must be re-centered in a cephalic direction
     • Shift the CR centering 1" for every 10* of beam <
   • ADULTS: On all positions (AP, Oblique, or Lateral) within the skull, chest, abdomen, and pelvis: shift the CR centering by 1/2" for every 5* of beam angle.
   • When imaging anatomy near the surface of the body facing the tube, NO CR COMPENSATION IS NEEDED!
   • When an x-ray beam is angled, the centering of the x-ray beam does not need to be adjusted when centering to exit points.
   • If the CR isn't compensated, you can face:
     • Anatomy of interest will be off-center
     • Closed joint spaces
     • Overlapping anatomical parts

2. CR compensation for transverse angles

   • Angling towards the patient left side, the CR should be re-centered to the right for every 5* of <; vice versa for the other side
   • DOWNSIDE OR UPSIDE ANATOMY: 1" of shift for CR centering for every 10* of angle / ex: 45* oblique lumbar spine, you would center 4.5" upside from the midline
   • RARE: 1" of shift for every 5* of < using a lateral position demonstrating downside anatmoy

3. SID

   • The rules in this chapter are applied to images taken at BOTH 40" and 72" SIDs