Which of the following is an example of a self-correcting rule for patient size when positioning?

A. AP chest, center to a point mid-way between sternal notch and xiphoid tip
B. PA chest, center one handbreadth down from C7
C. PA chest, center so when using 14 ´ 17 crosswise there is 1 inch of light field above shoulders
D. Upright AP abdomen, center so when using 14 ´ 17 lengthwise the top of the light field is at axilla

Answer: A