Quality Assurance and Phantoms Flashcards

A sonographer is performing a quality assurance test on a duplex ultrasound system to verify the accuracy of spectral Doppler velocity measurements. Which type of phantom is most appropriate for this task?

Answer: Doppler flow phantom

A Doppler flow phantom is specifically designed to evaluate Doppler systems. It contains a blood-mimicking fluid that moves at known velocities through tubes, allowing for the verification of velocity accuracy, color flow sensitivity, and spectral Doppler measurements. The other phantoms are designed for B-mode imaging evaluation.

While performing a routine QA scan on a phantom with pins spaced exactly 30 mm apart vertically, a sonographer measures the distance between two pins as 32.5 mm. This indicates a potential issue with which system parameter?

Answer: Vertical distance accuracy

Vertical distance accuracy assesses the system's ability to correctly measure distances parallel to the ultrasound beam's axis. A discrepancy between the known distance in the phantom and the measured distance on the system indicates a calibration error in depth measurement.

A quality assurance program requires testing the system's ability to place echoes in their correct positions on the display, ensuring that a pin target appears in the same location whether imaged from the top or side of the phantom. Which parameter does this test evaluate?

Answer: Registration accuracy

Registration accuracy is the ability of the system to display echoes in their proper anatomical positions on the screen. This test ensures that the system's internal coordinate system is correctly calibrated, so structures are mapped accurately in A-mode, B-mode, and M-mode.

During a quality assurance check, a sonographer notes that small reflectors located in the first centimeter of the image, immediately below the transducer face, are not visible. This finding suggests a problem with which performance parameter?

Answer: Dead zone

The dead zone is the region near the transducer face where imaging is inaccurate due to the time required for the system to switch from transmitting a pulse to receiving echoes. Reflectors within this zone may not be properly displayed. It is measured by finding the shallowest depth from which a uniform echo is displayed.

A sonographer performs a sensitivity test as part of a quality assurance protocol. This test is designed to assess the system's ability to:

Answer: detect and display weak echoes from deep structures.

Sensitivity, also known as maximum depth of penetration, evaluates the ability of the ultrasound system to detect and display the weakest-amplitude echoes from reflectors located deep within a phantom. It is a measure of the system's overall performance in penetrating tissue and receiving faint signals.

Compared to the AIUM 100mm test object, which is filled with a non-attenuating fluid, what is a primary advantage of using a tissue-equivalent (TE) phantom for routine quality assurance?

Answer: It allows for the evaluation of grayscale and contrast resolution.

Tissue-equivalent (TE) phantoms are made of materials that mimic the acoustic properties of soft tissue, including speed of sound, attenuation, and scattering. This allows for the subjective assessment of grayscale display, contrast resolution, and overall tissue texture, which cannot be evaluated with the anechoic, non-attenuating AIUM 100mm test object.