Ideally, the cathode end of an x-ray tube should be positioned to take advantage of the "heel effect" of the tube. Where should the cathode be placed for an AP thoracic spine?
A) Toward the head
B) Toward the feet
C) Head or foot end
D) Variable, depending on body habitus

Question

Quizplus · Accepted Answer

The heel effect states that the x-ray beam intensity is higher at the cathode end and lower at the anode end. Therefore, the cathode end should be placed towards the feet in order to take advantage of this effect when imaging the thicker and denser thoracic spine area. Placing the cathode towards the head may result in poor image quality due to decreased beam intensity at the thicker portion of the spine. The head or foot end option is too vague and does not specify which direction the cathode should be facing. The cathode position should not vary based on body habitus for this specific imaging scenario.

Ideally, the Cathode End of an X-Ray Tube Should Be