New developments
For almost 100 years, X-ray tube architecture has relied heavily on the design developed by William Coolidge, where it employs one hot tungsten filament as the electron source and the output of the tube is one X-ray beam.

GE Healthcare is currently working on a distributed X-ray source that represents a dramatic technology shift from the traditional Coolidge X-ray tube architecture, says David Mliner, general manager of global X-ray generation for GE.
Industry experts say this X-ray source could open the door towards exciting new medical X-ray system designs such as Inverse Geometry CT, in addition to applications in vascular imaging and mammography.

The company is the first to demonstrate a high power X-ray multisource—60 kW per source measured—which is critical for achieving high resolution, low-dose images.

Get the lead out
Another thing that companies are focusing on when it comes to the X-ray tubes is the amount of lead inside the tube assemblies.

“As we explore new development and look at the next generation of products, we are looking into how we can reduce the lead content,” says David Frick, operations manager for Dunlee. “I can see the day in the not-so-distant future when we may have a lead-free solution.”

Also new to the industry is the way that power is being measured in X-ray tubes. “Historically, we considered the heat storage capacity of the anode (or target) in kilo heat units (kHU) or millions of heat units (mHU),” Varian’s Hurlock says. “Now, with faster throughput, the limiting factor has become the power of the tube over time, as described by watts continuous usage.”

The heat storage in the anode no longer gates the X-ray tube power, so the ability to manage and dissipate heat is more important.

“Varian invented the anode end-grounded technology for X-ray tubes used in CT scanners,” Hurlock says. “That architecture has been adopted for CTs by the majority of CT system manufacturers. That anode end-grounded architecture manages heat much more efficiently than the traditional bipolar X-ray tube design. Look for big improvements as that technology moves from CT to other modalities.”

Options abound
In the tube market industry, what people are most excited about is having options. In 2009, the market was abuzz about the availability of used GE MX240 and Siemens Stratton CT tubes are coming into the replacement marketplace. That’s still riding a wave of interest.

“I think the most important factor hospitals need to look at is the reliability of the product they are choosing,” Dunlee’s Frick says. “There are options in the market to buy low-cost replacements for X-ray tubes. However, in many cases, those low-cost options have much shorter service life, and in the end it would be more expensive.”

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