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| ImagIng EssEnTIals Ventrodorsal projection: thoracolumbar Junction For the thoracolumbar junction ventrodorsal projection, position the patient in dorsal recumbency (Figure 4). • If a trough is used, place the entire thoracic spine within the trough to eliminate edge artifacts. • Extend the skull and neck and align with the manubrium. • align the sternum over the thoracic spine; it should be superimposed with the thoracic spine on the final image. • Tape the thoracic limbs either together or individually and pull cranially. • Tape the pelvic limbs individually and pull caudally. Ventrodorsal collimation For the ventrodorsal projection, the FOV should: • Include the thoracic vertebral bodies, with only the immediate rib heads and soft tissues visualized. • Exclude the lateral body wall and lungs of the thoracic cavity. a B Figure 4. Dog positioned for ventrodorsal projection of the thoracolumbar spine (A) and corresponding radiograph (B). For all patients: • Palpate the xiphoid of the sternum and the curve of the last rib in the lateral body wall. • Place the center of the FOV halfway in between these landmarks, with the horizontal line of the FOV placed midline. • Place the radiographic marker on the soft tissues of the ventrum at the most lateral edge of the collimated FOV. aDDitional Views Ventrodorsal oblique projection: thoracic spine Subtle lesions, fractures, and intervertebral disk disease are a few of the conditions that may require a ventrodorsal oblique projection of the spine (Figure 5). • From the straight ventrodorsal position of the thoracic spine, obliquely rotate the patient to the left approximately 10° to 15°; then take the radiograph. • Rotate the patient to the right approximately 10° to 15° and take a second radiograph. Collimate as described for the ventrodorsal projection of the thoracic spine (page 60). The ventrodorsal oblique thoracic spine projection requires a larger collimated FOV on the lateral aspect due to the curvature of the spine in that region. the cervical spine (C7). • The caudal border should, at least, include lumbar vertebra 1 (L1). • For the lateral position, the rib heads should be superimposed at the vertebral body level. QualitY control To make certain the desired technique has been achieved, use the following guidelines to determine whether the appropriate anatomy is included in the images. thoracolumbar Junction For the lateral projection of the thoracolumbar junction: • The cranial border should include the caudal aspect of the thoracic spine near the level of thoracic vertebra 11 (T11). • The caudal border should, at least, include lumbar vertebra 3 (L3). thoracic spine For the lateral projection of the thoracic spine: • The cranial border should include the caudal aspect of 62 Today's Veterinary Practice May/June 2013 For the ventrodorsal projection of the thoracic spine: • The cranial border should include the caudal aspect of the cervical spine at the level of C7. • The caudal border should, at least, include lumbar vertebra 1 (L1). • The spinous processes should be superimposed over the thoracic vertebral bodies.