Which aspect of imaging does the line pairs phantom directly measure?

The line pairs phantom 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. By using a series of parallel lines of varying widths, the line pairs phantom allows for the assessment of how well an imaging system can depict the fine details necessary for accurate diagnosis.

In practice, the line pairs displayed on the phantom will become indistinguishable at a certain point if the spatial resolution is inadequate. This characteristic helps technologists understand the limits of the system in capturing detailed images and assists in determining whether adjustments or calibrations are necessary to improve image quality.

While other aspects such as image brightness, contrast resolution, and signal strength are also important in imaging, they are not directly measured through the line pairs phantom. Image brightness pertains to exposure levels, contrast resolution relates to the capability of differentiating between different tissue densities, and signal strength refers to the overall clarity of the image rather than the fine details represented.