tube life
Expected useful life of an X-ray tube, typically measured in scans, mA·s, or hours depending on modality. The single most-watched lifecycle metric on any CT, interventional, or fluoroscopy refurb purchase. Tube wear is duty-cycle-driven, not calendar-driven — a 5-year-old tube in a low-volume practice may have less wear than a 2-year-old tube in a high-volume cardiac cath lab.
Why it matters to buyers: Single biggest replacement cost on CT, interventional, and (sometimes) fluoroscopy refurbs. Check tube hours / scan count / heat-units on every refurb purchase. Plan capital around tube-replacement cycles, not scanner-lifespan calendar age. Tube models matter — Straton, Vectron, Gemstone Clarity, MegaCool, Philips MRC each have distinct refurb economics and aftermarket programs.
Why it matters to engineers: mA·s is the best wear proxy on CT; scan count is the standard proxy on interventional. Anode bearing noise is the end-of-life warning before arcing — listen during high-mA fluoroscopy runs. Tubes also age via vacuum integrity (eventual gas-up), filament emission, and target wear (arc damage, focal-spot drift). Replacement is not a field repair on most modalities; plan the outage with parts and recertification physicist time built in.