Lesson 1, Topic 1
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Introduction to Radiographic Positioning

April 11, 2024

Introduction

This chapter introduces the subjects of anatomy and radiographic positioning, including the terms to depict radiographic projections and body positions. Details of everyday tasks performed during radiographic procedures are also included. Details include selection, use, and alignment of the x-ray tube the image receptor (IR) and the body part, patient instructions and radiographic marker use and placement.

Introduction to Radiographic Positioning

Learning Objective: Explain radiographic terminology, positions, and projections.

This chapter introduces the subjects of anatomy and radiographic positioning, including the terms to depict radiographic projections and body positions. Details of everyday tasks performed during radiographic procedures are also included. Details include selection, use, and alignment of the x-ray tube the image receptor (IR) and the body part, patient instructions and radiographic marker use and placement.

Terminology Review

Learning Objective: Identify the correct terminology to describe radiographic positions and projections.

Radiographic positioning instructions frequently include terms describing the relationship of body parts to each other and the location or orientation of body surfaces or structures in space. Terms that indicate these anatomic relationships are based on anatomic position. (Refer to Chapter 6 for more information on the anatomic position and medical terminology.) In addition to the terms covered in Chapter 6, limited operators must be familiar with the following terms to describe anatomic relationships, orientations, and relationships accurately:

• Anterior: Forward or front portion of the body or body part
• Posterior: Backward or back portion of the body or body part; opposite of anterior
• Central: Pertaining to the middle area or main part of an organ or body part
• Caudal/caudad: Away from the head
• Cephalic/cephalad: Pertaining to the head
• Distal: Away from the source or point or point of origin
• Proximal: Toward the source or point of origin
• Peripheral: Away from the central mass of an organ, toward its outer limits; the opposite of central
• External: To the outside, at or near the surface of the body or body part
• Internal: Deep, near the center of the body or a body part; opposite of external
• Plantar: Referring to the sole of the foot
• Parietal: Referring to the walls of a cavity
• Visceral: Pertaining to organs

Procedures for radiographic positioning are also described using body planes and body positions (see Chapter 6 for additional details).

Radiographic Positions

Learning Objective: Describe various radiographic positions.

Radiographic positions describe the placement of the body part in relation to the radiographic table or IR.
For a decubitus position, the patient is recumbent with the central (CR) horizontal or parallel to the floor. This position is named according to the body surface on which the patient is lying: lateral decubitus (left or right), dorsal decubitus, or ventral decubitus.
A lateral position is accomplished by placing the body or body part with the sagittal plane parallel to the IR. It is named according to the side adjacent to the radiographic table or IR.
A lordotic position results in angulation of the coronal plane of the chest with the IR. This is achieved by having the upright patient lean back so that only the dorsal aspect of the shoulders is in direct contact with the IR.
An oblique position is achieved when the body or body part is placed so that the coronal plane is not parallel with the radiographic table or IR. The description is stated as a degree of rotation, either from a body plane or toward the affected side.

Radiographic Projections

Learning Objective: Describe various radiographic projections.

A radiographic projection identifies the path of the CR from the radiographic tube through the patient to the IR. Most projections are named in anatomic terms based on the entrance and exit points of the CR in the body.
For anteroposterior (AP) projections, the CR enters the anterior surface and exits the posterior surface of the body or part.
For posteroanterior (PA) projections, the CR enters the posterior surface and exits the anterior surface of the body or part.
Lateral projections are those in which the sagittal plane of the body or body part is parallel to the IR. Lateral projections are always named for the side of the patient that is nearest the IR. Lateral projections of the extremities are further described with the lateral or medial entrance and exit of the CR: mediolateral or lateromedial.
Oblique projections are those in which the body is rotated so that the CR travels through the body on an oblique plane rather than following an anatomic plane. Oblique projections are named according to the entrance and exit points of the CR. For example, in an AP oblique position, the CR enters the anterior surface of the body and exits the posterior surface.
Axial projections are images taken with a longitudinal angulation of the CR of 10 degrees or more. The angle may either be cephalad (toward the head) or caudad (away from the head).
Tangential projections are produced by directing the CR to “skim” the profile of the subject. The tangential projection is typically utilized to demonstrate the patella and patellofemoral joint space.