Computed Tomography Technologist Practice Exam

The correct choice is a line-pair per millimeter phantom because it is specifically designed to evaluate spatial resolution in imaging systems. Spatial resolution refers to the ability of an imaging system to distinguish between two closely spaced objects, and this type of phantom consists of a series of alternating dark and light lines or bars.

When the imaging system processes this phantom, it generates a response that indicates the smallest distance at which the system can effectively separate the individual lines. The result is typically measured in line pairs per millimeter (lp/mm), allowing for quantifiable assessment of spatial resolution capabilities.

In contrast, a water phantom is primarily used for calibration and dose measurements, a uniform density phantom provides a uniform material to check for consistency across an image, and a matrix phantom may assess various imaging characteristics but is not specifically tailored for measuring spatial resolution. Thus, the line-pair per millimeter phantom is uniquely suited to determine how effectively a CT system can resolve fine details in images.