Proper radiographic positioning is essential to high-quality radiographs. Find out why.
Like a seasoned photographer in the Arctic Circle creating their shot, radiologic technologists know the importance of perspective.
They use it to create the illusion of three dimensions on a flat surface.
The human brain uses visual clues to immediately deduce which objects are farther or closer away from the observer.
The application of deliberate radiographic positioning allows radiologists to effectively visualize the different tissues of the body and locate pathologies.
A Primer on Radiography
Advanced medical imaging technology allows for unparalleled visualization of the hidden world inside of bodies. However, the traditional X-ray remains an essential tool due to its cost-effectiveness, ease of use, and widespread availability.
X-ray tubes project onto a receptor. The part of the body to be evaluated is placed between the x-ray tube and the receptor. Different tissues of the body absorb the x-ray to varying degrees depending on their consistency.
This leaves a ‘shadow’ that is converted to an image.
What Is Radiographic Positioning?
A standard anatomical position is a way to ensure that a universal language exists when describing the body. Imagine a person standing up straight with their arms outstretched and palms facing forward.
With this in mind, posterior refers to the back half of the body. Anterior means that a structure is closer to the front half of the body. For example, the tip of your nose is anterior to the back of your head.
Structures that are farther from the bottom of your toes are said to be superior anatomically. Inferior is defined as being lower in position.
Lateral and distal structures stray from the midline. Medial and proximal ones stay central.
The final image depends on the direction and angle that the x-ray passes through the body.
Anteroposterior (AP) projections enter the body through the front of the chest and leave through the back. Posteroanterior (PA) projections, logically, do the opposite. Projections going from side-to-side or diagonally are lateromedial and oblique, respectively.
What Are the Most Important Radiographic Positions?
There are several factors to consider when deciding which is the best radiographic position and projection to use.
Before proceding with the X-ray order, consider:
- Who is the patient?
- What is their presentation?
- What is the diagnostic differential?
- Are there any special factors? (disability, pregnancy, etc)
- What resources are available?
Chest x-rays are among the most commonly ordered procedures in medicine. They can show evidence of pneumonia, acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disorder (COPD), lung cancer, cardiomyopathy, heart failure, and many other disorders.
Physicians generally order PA and lateral chest x-rays when lung or heart disease is suspected. It can be invaluable to keep records of both of these in order to provide proper follow-up.
PA projection on film appears as if the patient is facing you. Their right side will correspond to your left. A lateral view is useful because two structures that are ‘behind’ one another may superimpose on a PA view and become indistinguishable.
An AP chest x-ray is less useful in most cases for several reasons. The heart is enlarged and renders it more difficult to visualize the pulmonary structures. The mediastinum is also enlarged. Together, this makes the lungs appear underinflated.
Pulmonary vasculature is also magnified in this view, leading to the appearance of interstitial infiltrate.
Signs of intestinal obstruction due to various causes may be shown radiographically. AP and PA may be used in conjunction particular with obese patients.
Although abdominal radiographs are sometimes ordered, one should remember that it does not replace a thorough history and physical exam and that there may be a better imaging study for these patients.
Shoulder X-ray Views
The shoulder joints consist of various bones, tendons, muscles, blood vessels, nerves, and other structures in a confined area. Shoulder x-rays are often ordered in conjunction with CT or MRI scans. This is useful in patients with suspected trauma, shoulder pain, arthritis, or restriction of movement.
The AP view is useful for visualizing the glenohumeral joint, clavicle, superior ribs, and proximal humerus. The lateral view best demonstrates any suspected shoulder dislocation.
Other shoulder x-ray views are indicated for certain trauma patients. A common one in these patients is called the modified trauma axial projection.
The Garth projection is a modification of this view specifically when glenohumeral dislocations are suspected. Other include the Grashey (AKA the true AP view) view, the Neers view, the axillary view, and the Stryker view.
Continuing Education in Radiology
The field of radiology, like the vast majority of medical specialties, is highly competitive and continuously evolving.
Things that were taught 10 years may now be outdated.
The best way to stay competitive professionally and improve the care you provide for your patients is to seek to improve your knowledge and ability through continuing education. You can earn CE and CME credits through these courses and even take online tests for X-ray, CT, MRI, and other imaging modalities.
Bringing It All Together
There are always certain things to consider when choosing the most appropriate radiographic positioning for each patient. This will depend on the particular characteristics of your patient, such as age and body type, the current condition, the part of the body to be evaluated, and the availability of imaging modalities in your health center.
Radiographic positions will always be important to know. They could make the difference between making and missing a crucial diagnosis.