Which imaging modality uses a gantry with X-ray tube and detectors rotating around the patient?

Which imaging modality uses a gantry with X-ray tube and detectors rotating around the patient?

• A. MRI
• B. Ultrasound
• C. Computed Tomography
• D. PET

Answer: (C)

This question is about how computed tomography works: it uses a gantry that houses an X-ray tube and a ring of detectors, and this assembly rotates around the patient to collect data from many angles. As the tube emits X-rays and the detectors measure how much radiation passes through the body from different directions, the system gathers a complete set of projections. Those projections are then mathematically reconstructed to form cross-sectional images of the body, showing differences in tissue attenuation with high spatial resolution. This setup—an X-ray source together with detectors rotating around the patient—is distinct from MRI, which uses strong magnetic fields and RF signals; from ultrasound, which relies on sound waves and a handheld transducer; and from PET, which uses radiotracers and detectors arranged around the patient without an X-ray source rotating. The rotating gantry with X-ray tube and detectors is the hallmark of CT imaging.

This question is about how computed tomography works: it uses a gantry that houses an X-ray tube and a ring of detectors, and this assembly rotates around the patient to collect data from many angles. As the tube emits X-rays and the detectors measure how much radiation passes through the body from different directions, the system gathers a complete set of projections. Those projections are then mathematically reconstructed to form cross-sectional images of the body, showing differences in tissue attenuation with high spatial resolution.

This setup—an X-ray source together with detectors rotating around the patient—is distinct from MRI, which uses strong magnetic fields and RF signals; from ultrasound, which relies on sound waves and a handheld transducer; and from PET, which uses radiotracers and detectors arranged around the patient without an X-ray source rotating. The rotating gantry with X-ray tube and detectors is the hallmark of CT imaging.