Radiographic Positioning

Friday, February 13, 2015

Radiographic Positioning : Radiography

The radiographic positioning terminology used by the American Registry of Radiologic Technologist (ARRT) and Canadian Association of Medical Radiation Technologist (CAMRT) are constantly the same with the following four common
terminology used in radiology:

  • Projection
  • Position
  • View
  • Method
But the only difference is that the term view is commonly used in Canada for some projections and positions.

What is Position?

The term position is used in two ways in radiology. One is to identify the entire posture of the patient or the general body position. It can be termed to patient for example as upright, seated, or supine.  The other use of position is to specify the placement of the body part in relation to the radiographic table or image receptor during radiographic imaging. The radiographic position and may be a right lateral, left anterior oblique, or other position depending on the examination and anatomy of interest.  Through radiography, the overall body positions are united with radiographic positions to produce the applicable image. For clarification of the positioning for an examination, it is often necessary to include references to both because a particular radiographic position such as right lateral can be achieved in several general body positions like upright, supine, lateral recumbent and etc. with differing image outcomes. Specific description of general body positions and radiographic positions follow.

What is Projection?

The term projection is defined as the path of the central ray as it exits the x-ray tube and goes through the patient to the image receptor. Most projections are defined by the entrance and exit points in the body and are based on the anatomic position. AP projection for example are obtained when the central enters anywhere in the front or anterior surface of the body and exits the back or posterior. Regardless of which body position where patient in supine, upright, prone, and others, if the central ray enters the anterior body surface and exits the posterior body surface the projection is termed an AP projection.
Projection also can be termed by the relationship formed between the central ray and the body as the central ray passes through the entire body or body part like for example, the axial tangential projection.
  • AP and PA Projections
  • Axial Projection
  • Tangential Projection
  • Lateral Projection
  • Oblique Projection
For additional clarification, projection may be defined by the entrance and exit points and by the central relationship to the body at the same time. In PA Axial projection for example, the central ray enters the posterior body surface and exits the anterior body surface following an axial or angled trajectory relative to the entire body or body part. Axiolateral projections also use an angulation of the central ray, but the ray enters and exits through lateral surface of the entire body or body part.

List of Radiographic Examinations and Positioning

MRI Patient Positioning

Correct patient positioning, placement of patient within the coil and proper immobilization techniques are important factors in MRI patient positioning. These are describe relatively to the light system as follow:
  • The longitudinal alignment light refers to the light running parallel to the bore of the magnet in the Z axis.
  • Horizontal Alignment light refers to the light that runs from left to right of the bore of the magnet in the X axis.
  • The Vertical alignment light refers to the light that runs from the top to the bottom of the magnet in the Y axis

The following procedure are examined with the patient placed head first in the magnet:

MRI Positioning
MRI Laser Positioning
  • Head and Neck
  • Chest
  • Cervical Thoracic and Whole Spine
  • Abdomen – in this examination areas superior to the iliac crest are included.
  • Shoulders and UpperLimb 

Anatomical Regions are examined with the patient placed Feet first in the Magnet.

  • Pelvis
  • Hips
  • Lower Limbs
  • Knee

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