Which of the following cannot be evaluated with a tissue-equivalent phantom?

• A. Axial resolution
• B. Lateral resolution
• C. Slice thickness
• D. Temporal resolution

Answer: (D)

Tissue-equivalent phantoms are used to assess imaging systems by simulating how real tissue interacts with the imaging modality, providing a stable medium to measure spatial performance. They let you quantify how well fine details are resolved along the direction of the beam (axial resolution) and across the beam (lateral resolution), and they also help evaluate how accurately a system can distinguish a thin slice (slice thickness). Because the phantom is static, these tests focus on the geometry and timing of the image capture related to spatial characteristics rather than any motion.

Temporal resolution, by contrast, is about how quickly the system can acquire images and distinguish events over time—the frame rate and the time response. To test this, you need motion or changing targets to see how rapidly the system updates and how well rapid changes are tracked. A simple tissue-equivalent phantom doesn’t provide that dynamic information, since it doesn’t move or change during imaging.

So, temporal resolution cannot be evaluated with a basic tissue-equivalent phantom; dynamic phantoms or moving targets are required to assess that aspect.