Jandres right
The first tube I replaced on a Shimadzu CT was a Varian - fitted into the unit from new, Our Siemens Skull unit had a Comet Tube, many more examples
We represent Dunlee in the UK so replacement tubes or intensifiers etc for most equipment is not an issue, Elscint, GE, Picker/Marconi through to Toshiba, all in accordance with BS EN ISO standards as Jandre states, and with the world becoming smaller with access to remote diagnostics and technical training, manuals and spares, qualified engineers are less of an issue these days.
What is a difficult issue though is perception - changing it is a real problem - not so much in the private sector but the NHS, the manufacturers can exert a huge influence, it was taking some time and a great deal of effort to change hearts and minds.
I think we will follow large parts of the globe, looking at support for units over a certain age, where we can, I think we should, a big difference can be made.
Geoffs right also but if you can provide a equal or better solution together with those using the equipment, out from under the porch is not such a bad place to be.
Darren