Which of the following describes a fact about third-generation CT scanners?

The fact that describes third-generation CT scanners is that the tube is fixed to the array. In these scanners, the x-ray tube and detector array rotate together around the patient. This configuration allows for continuous data collection during the rotation, leading to improved image quality and faster scan times. The fixed position of the tube in relation to the detector array in third-generation scanners is a defining characteristic that distinguishes them from earlier models.

Third-generation scanners employ a fan-shaped beam rather than a parallel beam, so the first choice does not apply. While third-generation scanners effectively capture data across a broader field of view, they are designed to cover the entire field rather than just a part of it, which makes the third option inaccurate. The concept of a rotating collimator is not applicable here, as the technology utilized in third-generation scanners does not incorporate this feature.