Different views (also known as projections) of the chest can be obtained by changing the relative orientation of the body and the direction of the x-ray beam.
The most common views are posteroanterior, anteroposterior, and lateral.
In a posteroanterior (PA) view, the x-ray source is positioned so that the x-ray beam enters through the posterior (back) aspect of the chest and exits out of the anterior (front) aspect, where the beam is detected.
To obtain this view, the patient stands facing a flat surface behind which is an x-ray detector.
A radiation source is positioned behind the patient at a standard distance (most often 6 feet, 1,8m), and the x-ray beam is fired toward the patient.

In anteroposterior (AP) views, the positions of the x-ray source and detector are reversed: the x-ray beam enters through the anterior aspect and exits through the posterior aspect of the chest.
AP chest x-rays are harder to read than PA x-rays and are therefore generally reserved for situations where it is difficult for the patient to get an ordinary chest x-ray, such as when the patient is bedridden.
 In this situation, mobile X-ray equipment is used to obtain a lying down chest x-ray (known as a "supine film").
 As a result, most supine films are also AP.

Lateral views of the chest are obtained in a similar fashion as the posteroanterior views, except in the lateral view, the patient stands with both arms raised and the left side of the chest pressed against a flat surface.
Different views (also known as projections) of the chest can be obtained by changing the relative orientation of the body and the direction of the x-ray beam. The most common views are posteroanterior, anteroposterior, and lateral. In a posteroanterior (PA) view, the x-ray source is positioned so that the x-ray beam enters through the posterior (back) aspect of the chest and exits out of the anterior (front) aspect, where the beam is detected. To obtain this view, the patient stands facing a flat surface behind which is an x-ray detector. A radiation source is positioned behind the patient at a standard distance (most often 6 feet, 1,8m), and the x-ray beam is fired toward the patient.
In anteroposterior (AP) views, the positions of the x-ray source and detector are reversed: the x-ray beam enters through the anterior aspect and exits through the posterior aspect of the chest. AP chest x-rays are harder to read than PA x-rays and are therefore generally reserved for situations where it is difficult for the patient to get an ordinary chest x-ray, such as when the patient is bedridden.  In this situation, mobile X-ray equipment is used to obtain a lying down chest x-ray (known as a "supine film").  As a result, most supine films are also AP.
Lateral views of the chest are obtained in a similar fashion as the posteroanterior views, except in the lateral view, the patient stands with both arms raised and the left side of the chest pressed against a flat surface.
Chest radiograph