Terminology, positioning, and imaging principles: Rad Tech

Terminology, positioning, and imaging principles form the foundation of radiographic practice. These concepts provide a common language for healthcare professionals and help ensure accurate patient positioning.

As a radiologic technologist, understanding the names and locations of body structures allows you to communicate effectively, position patients correctly, and produce high-quality diagnostic images that support patient care.

Now, the body can be divided into planes. The four planes commonly used in radiography are sagittal, coronal, horizontal, and oblique. The sagittal plane divides the body into right and left portions. If the sagittal plane divides the body into equal halves, it's called the midsagittal plane.

The coronal plane divides the body into front and back portions. Next, the horizontal plane divides the body into upper and lower portions. Finally, the oblique plane divides the body at an angle.

Many radiologic procedures are done to examine the bones and joints. Osteology is the study of bones, while arthrology is the study of joints. To understand how these bones and joints are organized throughout the body, let's first look at the overall structure of the skeleton, which is divided into the axial skeleton and the appendicular skeleton. The axial skeleton contains the bones along the body's central axis, including the skull, vertebral column, ribs, and sternum. The appendicular skeleton contains the bones of the upper and lower extremities, including the shoulders and pelvis.

Bone markings are used to describe projections or depressions on bones. A projection extends outward from a bone and can be described as a crest, process, head, or spine. Depressions are hollowed or recessed areas of bone and can be described as a fossa, fissure, or sinus.

When there’s a break in the continuity of a bone, it’s called a fracture. Fractures can be classified as closed, open, displaced, or nondisplaced.

Radiologic technologists use standardized anatomical and positioning terminology to communicate clearly and accurately, and to ensure consistent patient positioning and image evaluation.

Common anatomical relationship terms describe where one structure is in relation to another. For example, anterior refers to the front of the body, and posterior refers to the back of the body. Superior describes a structure closer to the head, while inferior describes a structure closer to the feet. Other commonly used relationship terms include medial, meaning toward the midline of the body, and lateral, meaning away from the midline.

Movement terminology is also important when positioning patients. Flexion decreases the angle between two body parts, while extension increases that angle. Abduction refers to movement away from the body's midline, and adduction refers to movement toward the midline.

Other common movement terms include pronation and supination, which describe rotation of the forearm and hand.

Positioning terminology describes how the body is placed for imaging. Common terms include projection, position, view, and method. Projection describes the path of the x-ray beam through the body, including where the beam enters and exits. Common examples include the anteroposterior, or AP projection, and the posteroanterior, or PA projection.

Position may describe the patient's overall body posture, such as standing, seated, prone, or supine. It can also describe how a specific body part is placed in relation to the image receptor, such as oblique, lateral, or decubitus positions.

View describes the anatomy as it appears on the image receptor. Because it reflects the anatomy's perspective rather than the x-ray beam's path, a view is considered the opposite of a projection.

Lastly, a method typically refers to a specific positioning technique that was named after the person who developed it, such as the Townes, Waters, or Caldwell methods.

Now, most radiographic examinations require a minimum of two projections taken at 90 degrees from each other. Obtaining images from these mutually perpendicular perspectives helps demonstrate anatomy accurately and reduces the chance that important structures will be hidden by superimposition, which is an overlap of different anatomical structures.

Additionally, when imaging long bones, ensure that both the proximal and distal joints are included on the image receptor to provide a complete diagnostic evaluation.

Radiologic technologists use established positioning routines and essential projections to consistently demonstrate the anatomy of interest. These routines are based on the anatomy being examined, the patient's condition, and the clinical indication for the imaging study.

After an image is acquired, it must be evaluated to determine whether it meets established evaluation criteria, including demonstration of anatomy, position, and exposure.