What is the degree and direction of CR angulation for a PA projection of the skull?

What is the degree and direction of CR angulation for a PA projection of the skull?

• A. 5 degrees caudad
• B. 10 degrees cephalad
• C. 0 degrees
• D. 0 degrees cephalad

Answer: (C)

For a PA projection of the skull, the central ray should be perpendicular to the image receptor with no angulation. This yields a true PA view, minimizes distortion and magnification, and places the center of the exposure at the nasion. Angling the CR would create an axial view and distort the relative positions of cranial structures, which is more appropriate for specialized axial skull projections. Therefore the required CR angulation is 0 degrees, with no cephalad or caudad tilt.

For a PA projection of the skull, the central ray should be perpendicular to the image receptor with no angulation. This yields a true PA view, minimizes distortion and magnification, and places the center of the exposure at the nasion. Angling the CR would create an axial view and distort the relative positions of cranial structures, which is more appropriate for specialized axial skull projections. Therefore the required CR angulation is 0 degrees, with no cephalad or caudad tilt.