Page 754 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.1 The upper gastrointestinal tr act 729

VetBooks.ir 4.13 4.14

Fig. 4.13 Laterolateral projection. Fig. 4.14 Positioning for a laterolateral radiograph
using a wireless digital cassette.

4.15 4.16

30°

Fig. 4.15 Lateral 30° dorsolateral oblique projection.

45° ventrolateral oblique (L45°V-LO) (Fig. 4.17) and Fig. 4.16 Using a metallic probe in a sinus tract
the dorsoventral (Fig. 4.18) views. The exact angle of to locate a diseased dental apex in a lateral 30°
obliquity necessary to obtain diagnostic radiographs dorsolateral oblique projection.
with the oblique views varies between approximately
30° and 45° for different individuals and breeds. The
laterolateral view results in superimposition of the The L30°D-LO projection results in radio-
contralateral maxillary and mandibular cheek teeth graphic separation of the contralateral cheek tooth
rows, which can result in difficulty in interpreting rows and is used to image the apices of the maxil-
changes to individual dental apices. This view is use- lary cheek teeth. The L45°V-LO projection is
ful to demonstrate the presence of exudate in the used to image the apices of the mandibular teeth.
paranasal sinuses, which are radiographically visible A greater angle from the horizontal is needed to
as fluid lines. There is minimal parallax distortion in separate the contralateral mandibular arcades on the
a rostrocaudal direction on this projection and it is image, which are closer together than their maxil-
therefore frequently used with radiopaque markers lary counterparts. The latter two projections may
such as metal probes. be further improved by separating the maxillary