Which modality shows 3 lp/mm resolution?

• A. Fluoroscopy
• B. Digital radiography
• C. Computed radiography
• D. Screen-Film Radiography

Answer: (A)

Line pairs per millimeter measure how finely an imaging system can resolve alternating dark and light lines. Fluoroscopy is designed for real-time dynamic imaging, so its hardware sacrifices some sharpness to maintain smooth motion and reasonable dose. The result is a relatively modest spatial resolution, around 3 line pairs per millimeter. By comparison, screen-film radiography uses film and screens optimized for very high detail, often well above several line pairs per millimeter. Digital radiography and computed radiography provide good, flexible image quality but typically don’t reach the ultra-fine detail of screen-film in standard settings; their practical resolution tends to be lower and more variable, though improved with newer detectors. Therefore, the figure of about 3 lp/mm fits fluoroscopy, reflecting its real-time imaging priority over ultra-high resolution.