Terms and Positioning Techniques for all Species

Beam direction: named by the point at which the beam first passes into the body followed by the point at which it exits the body or region to reach the film. Films directed from the opposite direction are difficult to differentiate and markers must be placed on the film. Caudal/cranial and cranial/caudal views appear identical in small animals because radiographs have no depth.  Do not try to read or see depth in a radiograph!

Lateral medial (LM) view: The beam enters the lateral side and leaves the medial side.Small animal extremities are usually exposed as mediolateral projections.

Lateral projection of body cavities (abdomen,thorax): Named by the exit surface or that surface adjacent to the film. An animal in left lateral recumbency (right side up, left side down) when radiographed, produces a left lateral projection.

DV or dorsoventral: The beam enters the dorsal surface and exits the ventral surface. This is the standard position for small animal thoracic cavity images with the patient in the sternal recumbency (back upwards, abdomen on table).

VD or ventrodorsal: The beam enters the ventral surface and exits the dorsal surface.

Craniocaudal: The beam enters the cranial (front) side of the limb above the carpus and exits the caudal (back) of the limb.

Caudocranial: The beam enters the caudal aspect of the limb and exits the cranial aspect. Difficult or impossible to differentiate from the craniocaudal view.

DP or dorsal palmar (dorsoplantar): Taken from the front to the back of the limb distal to the proximal extent of the carpus.

PD or palmar dorsal (plantar dorsal): Taken from the back to the front of the limb distal to the proximal end of the carpus.

A radiograph is a two dimensional representation of a three dimensional object. To extrapolate the third dimension at least two radiographs must be taken at 90° to each other.  A dorsoventral view of the abdomen will have the medial to lateral and cranial to caudal dimensions, but will lack the dimension in the plane of the beam, dorsal to ventral. The lateral view will have the cranial to caudal and the dorsal to ventral dimensions, but will lack the  lateral to medial dimension. With both views (DV and lateral) all three dimensions are present and three dimensional information can be extrapolated. If, in the DV view, a shotgun pellet shows up superimposed on the kidney, it could be anywhere in the plane of the beam (subcutaneous, below, in  or above the kidney).Another view is  needed to place the pellet in three dimensions. A lateral view showing the pellet overlapping  the kidney would now place it in the kidney.

Anatomical Landmarks: certain organs or structures with specific locations are used to ascertain the side of the body or limb on the film. These should always be used to confirm that the markers are correct. Use radiographic landmarks to get your bearings. Some commonly used radiographic landmarks are as follows:

Reading Films:
Radiographs must be interpreted in a systematic manner. Extract maximum information from the entire film. Initially one must determine the region that has been radiographed. Anatomical landmarks help in orientation of  the views and indicate the direction of the beam. If lateral and medial structures are silhouetted (on the edges of the structure), then the beam was directed craniocaudally, dorsopalmarily or dorsoventrally depending on what was radiographed (e.g. a view showing the outline of the radial carpal (lateral structure) and ulnar carpal bones (medial structure) or the lateral edges of the ribs (lateral structures). Silhouetted caudal and cranial structures indicate that the beam was directed lateromedially or mediolaterally (e.g. accessory carpal bone silhouetted, or thoracic radiograph where the spines of the vertebrae and the sternum are at the edges of the film).
Head & Neck

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