Quality Assurance and Phantoms Flashcards
7 cards from real ARDMS SPI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Quality Assurance and Phantoms flashcards as text
Which phantom structure is used to assess axial resolution in an ultrasound system?
Answer: Closely spaced wire targets aligned along the beam axis
Wire targets placed at known separations along the beam axis allow measurement of the minimum resolvable distance in the axial direction.
What does the uniformity test on a QA phantom primarily evaluate?
Answer: Consistency of gray-scale brightness across the image field
Uniformity testing checks that the image brightness is homogeneous throughout the field, revealing gain, TGC, or transducer element dropouts.
A QA test reveals that the on-screen distance measurement reads 5.2 cm for a structure the phantom certifies as 5.0 cm. What does this indicate?
Answer: Caliper or distance accuracy error exceeding acceptable tolerance
A 4% error in distance measurement suggests a calibration issue with the system's speed-of-sound assumption or caliper circuitry.
Which parameter is assessed when using anechoic spherical targets of progressively smaller diameter within a tissue-mimicking phantom?
Answer: Contrast resolution
Detecting anechoic spheres against a uniform background tests contrast resolution, which reflects the system's ability to distinguish subtle echo-amplitude differences.
Which material property of a tissue-mimicking phantom most directly simulates the acoustic attenuation of soft tissue?
Answer: Attenuation coefficient of approximately 0.5 dB/cm/MHz
Soft tissue has an attenuation coefficient of ~0.5 dB/cm/MHz, and QA phantoms are formulated to match this value for realistic signal depth behavior.
During weekly QA, a sonographer notices the lateral resolution has worsened compared to baseline. What is the most likely cause?
Answer: One or more transducer elements have failed
Failed or weak transducer elements degrade the aperture and focusing ability of the array, directly worsening lateral resolution.
What is the primary purpose of recording baseline QA images when a new ultrasound system is installed?
Answer: To establish reference measurements for future performance comparisons
Baseline images provide documented reference values so that subsequent QA tests can detect degradation in system performance over time.