VTNE Diagnostic Imaging Techniques 3 — Questions and Answers
Question 1: In fluoroscopy, the unit of patient radiation dose most commonly monitored in real time is:
- mAs
- Air kerma (Gy) (Correct answer)
- HVL
- kVp
Correct answer: Air kerma (Gy)
Air kerma measured in Gray (Gy) is the standard real-time dose metric in fluoroscopy, often tracked at the reference point to estimate patient skin dose.
Question 2: Which MRI sequence produces images where fluid appears bright (hyperintense)?
- T1-weighted
- T2-weighted (Correct answer)
- STIR
- Gradient echo
Correct answer: T2-weighted
On T2-weighted sequences, fluids have long T2 relaxation times and therefore appear bright, making them useful for detecting edema, effusions, and CSF.
Question 3: A cat presents with suspected hypertrophic cardiomyopathy. Which echocardiographic measurement is MOST important to obtain?
- Aortic root diameter
- Left ventricular free wall thickness in diastole (Correct answer)
- Pulmonary artery diameter
- Right atrial area
Correct answer: Left ventricular free wall thickness in diastole
HCM is diagnosed by increased left ventricular wall thickness (≥6 mm in diastole in cats) measured in the absence of other causes of hypertrophy.
Question 4: What is the purpose of using a grid in radiography?
- To increase the mAs required
- To reduce scatter radiation reaching the image receptor (Correct answer)
- To collimate the primary beam
- To decrease patient dose
Correct answer: To reduce scatter radiation reaching the image receptor
A grid consists of lead strips that absorb scattered radiation produced in the patient, improving image contrast by reducing the scatter fog reaching the detector.
Question 5: During abdominal ultrasound, the spleen of a dog appears diffusely hyperechoic compared to the liver. This finding is MOST consistent with:
- Normal finding
- Splenic congestion
- Nodular hyperplasia or diffuse infiltrative disease (Correct answer)
- Acute splenic torsion
Correct answer: Nodular hyperplasia or diffuse infiltrative disease
A diffusely hyperechoic spleen relative to the liver is abnormal and most often associated with nodular hyperplasia, extramedullary hematopoiesis, or infiltrative neoplasia.
Question 6: Which positioning aid is MOST appropriate for keeping a patient's limb in true lateral for an orthopedic radiograph?
- Sandbags (Correct answer)
- Foam wedges
- Tape only
- Lead gloves held by an assistant
Correct answer: Sandbags
Sandbags provide firm, moldable support to maintain limb position without personnel entering the primary beam, complying with ALARA principles.
Question 7: The Mach effect artifact on a radiograph appears as a dark line at the interface of two structures of different opacity. It is caused by:
- Film processing errors
- X-ray tube failure
- Edge enhancement by the human visual system (Correct answer)
- Scattered radiation
Correct answer: Edge enhancement by the human visual system
The Mach effect is a perceptual phenomenon where the human visual system exaggerates contrast at edges, creating an apparent dark band at density interfaces.
VTNE Diagnostic Imaging Techniques 3
In fluoroscopy, the unit of patient radiation dose most commonly monitored in real time is: