Radiography Terminology and Projections

Vocabulary terms and definitions from the lecture notes on anatomical terminology, radiographic projections, and technical imaging factors.

Anterior

Refers to forward or front part of body

Posterior

Refers to back part of body

PA (Posterior-anterior) Projection

Perpendicular central ray enters the posterior body surface and exits the anterior body surface.

AP (Anterior-posterior) Projection

Perpendicular central ray enters the anterior body surface and exits the posterior body surface.

Right Lateral

Right side of the patient is placed closest to the IR; the central ray enters the left side of the body and exits the right side.

Oblique

Central ray enters the body or body part from a side angle following an oblique plane; may enter from either side of the body and from anterior or posterior surfaces.

RAO

Right anterior surface of the body placed closest to the IR; corresponds with a PA oblique projection.

LPO

Left posterior surface of the body placed closest to the IR; corresponds with an AP oblique projection.

Supine

Lying on back

Prone

Lying face down

Left Lateral Decubitus (AP)

Patient laying on their left side facing AP

Right Lateral Decubitus (PA)

Patient laying on their right side, facing the IR (PA)

Dorsal Decubitus (Left Lateral)

Patient laying on their back, left side closest to the IR

Ventral Decubitus (right lateral)

Patient laying on their stomach, right side closest to the IR

Clinical significance of decubitus positions

Essential for detecting air-fluid levels or free air in a body cavity where the air rises to the uppermost part; performed if a patient cannot assume erect position.

Fowler

Supine position with head higher than feet

Trendelenburg

Supine position with head tilted downward

Lordotic

Achieved by having the patient lean backward while in the upright position so only the shoulders are in contact with the IR

Abduction

movement of a part away from the center of the body

Adduction

movement of a part toward the center of the body

Flexion

Bending of a joint

Extension

Straightening of a joint; normal position of a joint

Inferior

Below

Superior

Above

Medial

Refers to parts towards median plane of body or towards the middle of another body part

Lateral

Refers to parts away from median plane of the body or away from the middle of another body part to the right or left

Proximal

Toward center of body

Distal

Away from center of body

Caudad

Refers to parts away from the head of the body

Cephalad

Refers to parts toward the head of the body

Common Cassette Sizes

$10 \times 12$ and $14 \times 17$

Technique

Milliamperage (mA), kilovolt peak (kVp), and exposure time (seconds); selected by the radiographer to produce a quality radiograph.

IR (Image Receptor)

Receives the energy of the x-ray beam and forms the image of the body part.

SID

Distance from the anode focal spot inside the x-ray tube to the IR; directly affects magnification and patient dose.

Relationship between SID and Magnification

The greater the SID, the less the anatomy is magnified.

Central Ray

Central or principal beam of x-rays, always centered to the anatomy of interest and the IR