Page 188 - A Practical Guide to Equine Radiography

CERVICAL SPINE 169

Right ventral-left dorsal oblique 5. Focus–film distance: 100 cm. If a grid is
VetBooks.ir (RV-LDO) and left ventral-right dorsal used, adjust the focus–film distance to the

distance specified for the grid.
oblique (LV-RDO) for articular process
(‘facet’) joints (Figs 15.17–15.26) 6. Angle the X-ray beam upwards 45–55
1. Stand the horse square with all limbs degrees from the horizontal, perpendicular
equally weight-bearing and extend the neck to the long axis of the neck. The articu-
slightly with the help of a head stand. Avoid lar process joints change their angulation
any tilting or rotation of the head and neck. from cranial to caudal requiring a shallower
2. Place the plate on the dorsolateral side of angle cranially and a steeper angle caudally.
the neck in landscape orientation, perpen- 7. Centre the X-ray beam at the jugular groove.
dicular to the X-ray beam. Beware that this The level depends on the area of interest:
may be higher than you think!
3. Indicate right/left (plate’s side) with a − Cranial neck: C1–C2
marker. − Mid neck: C3–C4
4. Position the X-ray machine on the ventro- − Caudal neck: C5–C6.
lateral aspect of the contralateral side of the
neck. It is helpful to palpate the neck and use
tape to mark position of the plate/centring.
− RV-LDO: outlines the right-sided articu- Beware that some tape is radiodense though
lar processes in an ‘end-on’ view and the and shows up on the radiograph!
left-sided articular process joints’ articu- 8. Align the field of view with the long axis of
lar spaces. the cervical spine and collimate around the
− LV-RDO: outlines the left-sided articular area of interest.
processes in an ‘end-on’ view and the 9. Exposure guide:
right-sided articular process joints’ artic-
ular spaces. − Cranial neck: 70 kVp, 20 mAs
− Mid neck: 80 kVp, 30 mAs
Note: this is the opposite way in the back − Caudal neck: 85 kVp, 55 mAs.
due to the different orientation of the artic-
ular process joints.

B
A

Figure 15.17 Diagram (A) and positioning (B) to obtain an RV-LDO view of the cervical spine that outlines the
right-sided articular processes in an ‘end-on’ view and the left-sided articular process joints’ articular spaces.

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