Which imaging modality uses a cathode ray tube to allow an observer to view a moving image?

Which imaging modality uses a cathode ray tube to allow an observer to view a moving image?

• A. Fluoroscopy
• B. Nuclear medicine
• C. Radiography
• D. Contrast material

Answer: (A)

Fluoroscopy provides real-time, moving X-ray imaging. In this technique the X-ray beam passes through the patient and the transmitted rays are captured by an image intensifier, converted to visible light, and displayed on a monitor. Historically that monitor was a cathode ray tube, which allowed observers to see and assess motion as it happened—for example, guiding a catheter, watching swallowing, or evaluating joint movement. The other options don’t fit this dynamic, live-display requirement: radiography gives a single still image, nuclear medicine images are typically static or time‑dependent but not viewed on a CRT for continuous real-time motion, and a contrast material is simply a substance used to improve visibility, not an imaging modality itself.

Fluoroscopy provides real-time, moving X-ray imaging. In this technique the X-ray beam passes through the patient and the transmitted rays are captured by an image intensifier, converted to visible light, and displayed on a monitor. Historically that monitor was a cathode ray tube, which allowed observers to see and assess motion as it happened—for example, guiding a catheter, watching swallowing, or evaluating joint movement. The other options don’t fit this dynamic, live-display requirement: radiography gives a single still image, nuclear medicine images are typically static or time‑dependent but not viewed on a CRT for continuous real-time motion, and a contrast material is simply a substance used to improve visibility, not an imaging modality itself.