Diagnostic Imaging
This domain tests radiographic positioning, safety, contrast studies, and basic ultrasound technique. It rewards systematic image assessment and radiation protection.
Core rules
- Take orthogonal views: a lateral plus a VD or DV for the thorax and abdomen. Include the entire region of interest and collimate to reduce scatter. Center the part and prevent rotation.
- ALARA: wear lead PPE, use a dosimeter, and avoid holding the patient in the beam. Use sandbags, troughs, and sedation when needed.
- Label films with patient, date, and view. Contrast studies require patient prep, correct dose, and timed images.
- Ultrasound needs gel, clipping, and a quiet dark room; it complements, not replaces, radiography.
Worked example
A dog has a chronic cough. The technician takes a right lateral and a VD thoracic radiograph. If only the lateral is taken, a left-sided or mediastinal lesion may be missed. The reasoning: two orthogonal views give three-dimensional location and are standard for thoracic evaluation. The technician also checks inspiration and exposure before submitting the study.
Traps
One-view studies, off-center positioning, rotated thorax, and motion artifact are common. Cropping the image or failing to include the whole structure limits interpretation. Never place an unprotected hand in the primary beam.