Noninterpretive Skills
What the exam tests
Noninterpretive skills cover quality and safety, ethics, informed consent, communication, radiation protection, contrast reactions, informatics, and basic biostatistics. Questions test practical decision-making, not image interpretation.
Core rules
- Sensitivity is the proportion of diseased patients who test positive; specificity is the proportion of nondiseased patients who test negative.
- Positive predictive value depends on disease prevalence; sensitivity and specificity do not.
- Informed consent requires capacity, disclosure of risks and alternatives, and voluntariness.
- Radiation protection follows ALARA and time, distance, and shielding.
Worked example
In a population of 1,000 patients with 10% disease prevalence, a test has 90% sensitivity and 90% specificity. Reasoning: true positives = 0.90 × 100 = 90; false negatives = 10; false positives = 0.10 × 900 = 90; true negatives = 810. PPV = 90/(90+90) = 50%. Even with a good test, half of positive results are false positives when prevalence is low.
Traps
Confusing sensitivity with PPV; assuming a highly sensitive test rules out disease regardless of prevalence; and omitting informed-consent elements.
Key points
- Sensitivity and specificity are prevalence-independent.
- PPV and NPV depend on prevalence.
- Informed consent requires capacity, disclosure, and voluntariness.
- ALARA uses time, distance, and shielding.
- Error reporting supports quality improvement.