Total gain = Flux gain (area input screen/area output screen). The spatial resolution of an II has improved over the last two decades. For example, for a pre 1970 II using a ZnCdS:Ag input screen, a spatial resolution of 2 lp/mm was rarely achieved. Modern IIs show values of 5-7 lp/mm.

Jeff Rondeau, president of 5 Star Imaging, Odessa, FL says that his company repairs and evaluates all X-ray tubes and IIs from Dunlee, Siemens, Varian and Thales. They also sell pre owned certified products tested at 5 Star Imaging to meet all OEM specifications. Rondeau said that that the life of an X-ray tube varies depending on its usage. "If an X-ray tube is sitting in a chiropractor's office it's not going to be used as much as it would be in an emergency room," says Rondeau. "Those that are not used frequently can last ten years or more, while those used on a regular basis may need to be replaced in a matter of months." 5 Star Imaging reloads, repairs and evaluates all X-ray tubes and IIs from Dunlee,




New and reloaded tubes

According to Ralph Babcock, general manager at Imaging Affiliates in Rural Hall, NC, refurbished tubes are tubes that have had some repairs done to them, without completely reloading the old housing with a new insert. "It can be as simple as changing and replacing the dielectric oil that is in the housing to replacing grid-switches and even anodes and cathodes," says Babcock. "When a tube is manufactured "new," the original manufacturer takes a housing and an insert and combines them to form a new tube-unit.

This new tube-unit will probably include a housing that has been refurbished to conform to original specifications and has had some parts replaced on it such as stators, gaskets, expansion-bellows, high-voltage receptacles and port-windows." Babcock says that all the original tube manufacturers "reload" x-ray tubes -- that is -- take a refurbished housing and load a new insert into this housing as well as some tube reloaders such as STAT, 5 Star and North American Imaging. "Reloaded tubes are tested to conform to the original performance specifications and are given the appropriate warranty that a so called 'new tube' would have," states Babcock. Refurbished tubes are also tested to this conformity (focal spot sizes, emission, high-voltage stability), but may or may not be given the same warranty as the new or reloaded tubes would have."

More Industry Reports