What refers to a system's ability to stop motion and produce blur-free images?

The term that refers to a system's ability to stop motion and produce blur-free images is temporal resolution. Temporal resolution is crucial in imaging modalities, like computed tomography (CT), where quick succession of images is necessary to capture moving structures, such as the heart or lungs, without motion artifacts.

High temporal resolution allows for faster image acquisition and effectively freezes motion, resulting in clearer and sharper images. This capability is especially important in dynamic studies where physiological processes are taking place rapidly, ensuring that the resulting images can be diagnosed accurately.

In contrast, other terms provided do not specifically pertain to the ability to capture motion-free images. Total collimation relates to the shaping and limiting of the radiation beam but not directly to motion capture. Surface rendering deals with creating a three-dimensional representation of the data set rather than stopping motion. Step artifact refers to a type of image artifact caused by the discrete steps in image acquisition, typically associated with lower temporal resolution, rather than being a descriptor of the quality of motion stopping in imaging.