Diagnostic Imaging: quality radiographs, ultrasound, and radiation safety
Diagnostic Imaging
This domain tests production of diagnostic-quality radiographs, safe use of ultrasound, contrast procedures, and radiation protection for patient and personnel.
Core rules and concepts
- ALARA: minimize time, maximize distance, collimate to the area of interest, wear lead apron and gloves, and wear a dosimetry badge. Never manually hold a patient without protection; use sandbags, ties, or sedation.
- Orthogonal views: two views at 90° for any lesion. Thorax: right and left lateral plus VD/DV, at peak inspiration.
- Technique: measure the thickest part with calipers, select kVp/mAs from a chart, center the beam, and position limbs parallel. OFA hip films require a symmetric ventrodorsal extended view.
- Ultrasound: real-time and operator-dependent; excellent for soft tissue, fluid, pregnancy, and guided sampling, poor for bone and lung detail.
- Contrast: barium or iodinated media; know contraindications (suspected perforation) and the timing of serial films.
Worked example
A lateral thorax shows asymmetric ribs and a wide cardiac silhouette. Rotation and expiratory films both widen the heart. Reposition and repeat at peak inspiration before diagnosing cardiomegaly; only then measure vertebral heart score (about 10.5 in dogs) on a well-positioned film.
Traps
Diagnosing from a single view. Mistaking skin folds or nipples for lesions. Accepting a moving or expiratory film. Shielding the patient but not the technologist. Assuming ultrasound replaces radiography for bone disease.