Question

What is the primary disadvantage of performing an AP projection of the chest rather than a PA?

1) More radiation exposure to the lungs
2) Distortion of the ribs
3) AP projection requires more kV as compared with the PA projection
4) Increased magnification of the heart

Answer 1

The primary disadvantage of an AP chest projection compared to a PA projection is increased magnification of the heart, leading to potential inaccuracies in assessing heart size.

Step-by-step explanation:

The primary disadvantage of performing an Anteroposterior (AP) projection of the chest rather than a Posteroanterior (PA) projection is increased magnification of the heart. When the X-ray beam passes from the anterior part of the body to the posterior in the AP projection, objects closer to the X-ray source, such as the heart, appear larger than they truly are. This can lead to inaccurate assessments of heart size, making the PA projection, where the heart is closer to the image receptor and thus less magnified, typically preferred. In addition, the body absorbs more x-ray photon energy when imaging is performed from an AP projection, as the rays have to pass through more tissue, especially in the region of the chest, before reaching the film.