Compare rotating-anode and stationary-anode tubes in terms of maximum power dissipation and typical applications.

• A. Rotating-anode has lower power and is used for mobile imaging; stationary-anode handles higher power.
• B. Rotating-anode handles higher power via heat distribution and higher exposure potential; stationary-anode has lower power handling and is used for lighter-duty imaging like dental radiography.
• C. Both have identical power handling; application depends on detector type.
• D. Rotating-anode is only used for dental imaging; stationary-anode for chest radiography.

Answer: (B)

The key idea is how heat management limits the maximum power the tube can safely dissipate and how that guides their best uses. A rotating-anode tube spreads the X-ray beam’s heat over a much larger surface area by spinning the target, so the same beam power doesn’t heat a single spot as intensely. This distribution raises the tube’s thermal capacity and lets you use higher exposure settings or longer exposures (higher exposure potential) without overheating. In contrast, a stationary-anode tube keeps the heat concentrated at the fixed focal spot, so its heat-dissipation capacity is lower. That makes it well suited for lighter-duty imaging where exposures are short and power requirements are modest, such as dental radiography. Because of the higher heat handling, rotating-anode tubes are preferred for general radiography and other applications requiring higher exposure levels, while stationary-anode tubes remain common where the workload is smaller.