Labeling x-rays. The rules are archaic, inconsistent, and sometimes confusing but:
The x-ray is labeled in the direction in which the beam passes. Examples include:
PA chest film - the x-ray beam passes from the posterior to the anterior side of the chest.
CC mammogram - the x-ray beam enters the breasts from above (Cranial) and exits below the breasts (Caudal).
However, this is not always the case. Examples include:
A "lateral elbow" film is not labeled “medial-lateral”.
A "left lateral chest" is taken with the left side of the chest closest to the film.
Right decubitus, A(anterior)P(posterior) or PA view, means the right side is down.
"Waters’ view" is an AP of the face taken with the head tilted up.
Regardless of how the film was exposed, you always view the image as you would view the patient; that is, the patient’s right is to your left, their left is to your right, and both on plain films and cross-sectional images.
This is usually in the anatomic position, i.e. patient upright, facing you, feet together, with the palms of their hands facing forward. Exceptions are seen with neurosurgeons and orthopedists who operate on the spine; they view spine films as if looking at the back of the patient, which is the direction from which they operate.
The correct answer to some questions is “I don’t know.”
It is the job of the radiologist to see that the film is correctly labeled and marked right or left.
How to look at a film:
Dim the lights.
Don’t get too close.
Check name, gender, age, and date.
Look at the entire piece of film.
Consider all views.
Anatomy or physics can explain everything on the film.
Treat the patient, not the x-ray.