RVT Quality Assurance and Safety 3 — Questions and Answers
Question 1: A carotid duplex study is flagged during a QA review because the ICA/CCA PSV ratio is 4.2 but the ICA PSV is only 110 cm/s. What is the BEST next step?
- Report as high-grade stenosis based on the ratio alone
- Correlate with waveform morphology and assess for contralateral occlusion (Correct answer)
- Repeat the study immediately with a different transducer
- Discard the ratio and classify by PSV alone
Correct answer: Correlate with waveform morphology and assess for contralateral occlusion
A high ICA/CCA ratio with a low absolute PSV suggests a low cardiac output state or contralateral ICA occlusion causing compensatory flow changes; clinical correlation is essential.
Question 2: Which accreditation body specifically focuses on vascular testing laboratories and requires compliance with published testing protocols?
- The Joint Commission (TJC)
- Intersocietal Accreditation Commission for Vascular Laboratories (ICAVL) (Correct answer)
- American College of Radiology (ACR)
- College of American Pathologists (CAP)
Correct answer: Intersocietal Accreditation Commission for Vascular Laboratories (ICAVL)
ICAVL is the primary accrediting body dedicated to vascular laboratories and evaluates physician oversight, equipment quality, personnel qualifications, and testing protocols.
Question 3: When establishing normal reference ranges for a vascular lab's ankle-brachial index (ABI) measurements, the data should be stratified by:
- Sonographer seniority level
- Equipment manufacturer
- Patient age, sex, and clinical indication (Correct answer)
- Time of day the test was performed
Correct answer: Patient age, sex, and clinical indication
ABI reference ranges and interpretation thresholds can vary with patient demographics and clinical context, so stratification ensures the lab's internal norms reflect its specific patient population.
Question 4: What does the term 'sentinel event' mean in the context of vascular laboratory patient safety?
- A near-miss event that was caught before reaching the patient
- An unexpected occurrence involving death or serious physical harm to a patient (Correct answer)
- A quarterly report submitted to the accreditation body
- A false-positive ultrasound finding requiring follow-up imaging
Correct answer: An unexpected occurrence involving death or serious physical harm to a patient
The Joint Commission defines a sentinel event as an unexpected occurrence that results in death, permanent harm, or severe temporary harm, requiring immediate investigation and response.
Question 5: A technologist notices the real-time B-mode image has a 'dropout' artifact in the far field during routine phantom testing. The MOST likely cause is:
- Excessive gain setting
- Air bubble trapped between the transducer and the phantom surface (Correct answer)
- Time-gain compensation (TGC) set too low in the far field
- Incorrect Doppler angle selected
Correct answer: Air bubble trapped between the transducer and the phantom surface
Air has very high acoustic impedance mismatch with tissue/gel, causing near-total reflection and creating acoustic shadowing that eliminates signal in deeper structures.
Question 6: In ALARA (As Low As Reasonably Achievable) practice for diagnostic ultrasound, which action BEST reduces thermal bioeffect risk during a vascular study?
- Increase the number of focal zones to improve resolution
- Minimize total scan time and use the lowest output power necessary to obtain diagnostic images (Correct answer)
- Use continuous wave Doppler rather than pulsed wave Doppler
- Increase frame rate to capture fast-flow events
Correct answer: Minimize total scan time and use the lowest output power necessary to obtain diagnostic images
ALARA requires minimizing both intensity and exposure duration; using the lowest power that yields diagnostically adequate images reduces thermal index and cumulative energy deposition.
Question 7: Which quality control metric is used to evaluate the consistency of a vascular lab's duplex grading of renal artery stenosis compared to subsequent CTA or angiography findings?
- Test-retest reliability coefficient
- Sensitivity and specificity with correlation to reference standard (Correct answer)
- Cronbach's alpha for internal consistency
- Intraclass correlation coefficient for PSV measurements only
Correct answer: Sensitivity and specificity with correlation to reference standard
Comparing duplex findings against a reference imaging standard calculates sensitivity and specificity, which quantify the lab's diagnostic accuracy for renal artery stenosis grading.
RVT Quality Assurance and Safety 3
A carotid duplex study is flagged during a QA review because the ICA/CCA PSV ratio is 4.2 but the ICA PSV is only 110 cm/s.
What is the BEST next step?