VTNE Diagnostic Imaging 4 — Questions and Answers
Question 1: In digital radiography, what does the term 'exposure index' indicate?
- The total radiation dose delivered to the patient
- A measure of detector exposure level relative to optimal (Correct answer)
- The kVp setting used during the exposure
- The number of exposures taken per study
Correct answer: A measure of detector exposure level relative to optimal
The exposure index is a numeric value indicating whether the detector received too little (underexposure) or too much (overexposure) radiation relative to the system's calibrated target.
Question 2: Which radiographic sign describes air within the intestinal wall (intramural gas) seen in necrotizing enterocolitis or emphysematous gastritis?
- Pneumoperitoneum
- Pneumatosis intestinalis (Correct answer)
- Ileus pattern
- Mechanical obstruction
Correct answer: Pneumatosis intestinalis
Pneumatosis intestinalis refers to gas trapped within the intestinal wall layers, which is a grave sign indicating bowel necrosis or severe mucosal compromise.
Question 3: A lateral skull radiograph of a cat shows lysis of the tympanic bullae with soft tissue opacity filling the bulla. The most likely diagnosis is:
- Temporomandibular joint ankylosis
- Otitis media/interna with bulla involvement (Correct answer)
- Nasopharyngeal polyp without bony changes
- Feline acromegaly
Correct answer: Otitis media/interna with bulla involvement
Lysis of the tympanic bulla combined with soft tissue opacity filling the bulla cavity is characteristic of chronic otitis media/interna with secondary osteomyelitis.
Question 4: What is the purpose of using the ALARA principle in veterinary radiology?
- To maximize image resolution at any radiation dose
- To keep radiation exposure as low as reasonably achievable (Correct answer)
- To standardize kVp and mAs across all patients
- To allow unrestricted radiographic studies without dose limits
Correct answer: To keep radiation exposure as low as reasonably achievable
ALARA (As Low As Reasonably Achievable) is the guiding radiation safety principle requiring minimization of exposure to patients, staff, and the environment while maintaining diagnostic image quality.
Question 5: On an ultrasound of the canine abdomen, which structure typically appears as a hyperechoic line with acoustic shadowing in the right cranial abdomen?
- The portal vein wall
- The right kidney cortex
- Gas within the duodenum (Correct answer)
- The gallbladder wall
Correct answer: Gas within the duodenum
Gas within the duodenal lumen produces a hyperechoic interface with dirty acoustic shadowing, a normal finding that can limit visualization of structures behind it.
Question 6: Which positioning aid helps prevent patient rotation when obtaining a true lateral thoracic radiograph?
- A sandbag placed on the thorax
- Foam wedges placed under the sternum and spine (Correct answer)
- Tape applied across the thorax
- Compression paddle over the caudal thorax
Correct answer: Foam wedges placed under the sternum and spine
Foam wedges placed under the sternum or dorsum support the patient's body and prevent axial rotation, ensuring the ribs on both sides are superimposed for a true lateral projection.
Question 7: In CT imaging, Hounsfield units (HU) are used to describe tissue density. Which value most closely corresponds to fluid (water)?
- -1000 HU
- 0 HU (Correct answer)
- +400 HU
- +1000 HU
Correct answer: 0 HU
Water is assigned a Hounsfield unit value of 0 by definition; air is -1000 HU and cortical bone is approximately +1000 HU, forming the anchors of the HU scale.
VTNE Diagnostic Imaging 4
In digital radiography, what does the term 'exposure index' indicate?