Dunlee's DA200P40+LMB tube

The rise of liquid metal bearing X-ray tubes

August 16, 2021
by Lauren Dubinsky, Senior Reporter
Much of the imaging technology in your facility is only as good as the X-ray tube inside of it. These vital components operate behind the scenes, so it’s easy to forget the work they do to generate each and every X-ray image you acquire.

The tube market has historically been difficult to break into, due to the cost of technology development and access to R&D, and experienced manufacturing engineering expertise. While major imaging OEMs like GE, Philips, Siemens and Canon manufacturer their own tubes, there are also independent tube manufacturers like Varex, the Dunlee brand of Philips, Chronos, and Richardson Healthcare.

These sophisticated components are not cheap, so ensuring you’ve got the best tubes for your technology is critical. From OEM offerings to the replacement market, we look at the latest crop of tubes, the rise of liquid metal bearing (LMB) tubes, a move away from ball bearings, innovations in service and maintenance partnerships, and the exciting potential for cold cathode tubes.

LMB takes off but ball bearings remain relevant
GE Healthcare has launched a newly engineered LMB tube called the Quantix 160 X-ray tube for its Revolution Apex CT system. It features a new flat emitter cathode design, which exceeds 16 centimeters of coverage, and has an ultrahigh-power reserve for high-resolution scanning.

It’s also designed to handle much higher rotational speed and force. It can withstand 75 G of G-force, which is significant since a fighter jet can typically handle 9 Gs, according to Aaron Goryl, general manager of service product management and healthcare technology management development for the U.S. and Canada at GE.

“It provides the necessary power to image comfortably all anatomies, regardless of the patient size, supports whole organ scanning or imaging without compromising imaging noise, or image noise or contrast,” he added.

With 2,000 employees turning out over 25,000 X-ray tubes per year and over 70 years in the industry, Utah-based Varex Imaging Corporation is one of the market leaders in OEM and replacement tubes. At the 2020 RSNA meeting, Varex introduced new LMB technology to its X-ray tube portfolio. The first two X-ray tubes in this new product family are a dual-ended CT application tube, the GS-547XX-L, and the first-to-market anode-end-grounded cardiovascular applications tube, the FP-309X-L, according to a statement.

Dunlee entered the LMB tube market with the launch of its CT3000 for mid-range CT scanners, which are not the usual candidates for this advanced technology.

“We do expect LMB tubes will play a dominant role in this market segment and the number of systems that use ball bearing tubes will steadily decrease,” said Martina Pieper, senior marketing manager at Dunlee.

“Hospitals see the advantage of LMB for daily work when there is higher patient throughput,” she added. “I think wherever workflow reliability and comfort counts, I'm sure the LMB technology will be the technology of choice.”

For now, Goryl says GE continues to see applications for both LMB and ball bearing tubes. It really boils down to the scanner, and the applications and purposes it will be used for. Patient volume, rotational speed and gantry load are all factors that may determine the amount of stress that will be put on the tube.

“Ball bearings, in general, can be a failure point when you put a lot of load or strain on the tube with gantry rotation, etc.,” said Goryl. “There are certain cases where ball bearing works just fine, but for the higher performance systems, LMB tends to be utilized on those technologies.”

One trend shaping OEM tube development is a new emphasis on building scanners with a focus on managing the whole system and reducing the number of service calls, according to Jason Launders, director of operations for the device evaluation group at ECRI.

“The more reliable you can make it, the better it's going to be for a customer and for you,” he said.

The replacement market
Dunlee launched its DA200P40+LMB CT tube for the replacement market, which is designed for the GE Revolution Evo and Optima CT660 CT systems. It features the company’s CoolGlide LMB technology that continuously circulates fluid to avoid friction, overheating and wear and tear.

“Users can turn on the system in the morning, it will run all day without any interruption,” said Pieper. “In COVID times, it's very nice that this saves preparation time and is especially useful for emergency exams.”

Chronos Imaging is also making a splash in the CT tube replacement market with its new LMB tubes. The company recently began manufacturing a number of LMB tubes due to the heat dissipation, reliability and quiet operation that this technology offers.

“They are generally more expensive to produce,” said Patrick Fitzgerald, president of Chronos. “While there has been a steady progression toward the use of LMB technology in higher end CT and interventional tube applications, I think there will still be a place for ball bearing technology in the more cost-effective tubes needed in lower-end CT and DR applications.”

That sentiment, regarding the need for both LMB tubes and ball bearing tubes, is something the industry seems to widely agree upon. It isn’t a case of one-size-fits-all or one technology completely replacing another.

“LMB provides a very smooth and quiet rotation of the anode, longer running time than the conventional bearing and additional cooling of the anode,” said Jerald L. Olsen, vice president of sales and business development at Richardson Healthcare. “While it has many advantages for the higher market-tier tubes, those advantages come at a price that may make this type of bearing cost prohibitive for lower-tier market tubes.”

Richardson Healthcare will be launching its ALTA750G X-ray tube in the fall of 2021. This tube is a form, fit and function replacement for the CXB-750G and is compatible with the Canon Prime, Prime II and Prime SP systems.

Remote monitoring during the pandemic
"CT, specifically, has had quite a lot of use in COVID-19 cases," said ECRI’s Launders. "It’s a high-value imaging device for the lungs and data is still coming out showing just how good it was at identifying patients and determining the best management for them."

Since CT systems were used more during the pandemic, reducing downtime was more important than ever. GE saw a greater interest in its OnWatch and Tube Watch remote monitoring services.

"We saw a lot of activity around remote monitoring and predictive service during COVID times," said Goryl. "There was a lot of focus on who's in the healthcare setting."

Tube Watch leverages artificial intelligence, machine learning and software analytics to remotely monitor tube health and predict a potential failure. If there is an issue, a GE engineer can remotely run a comprehensive assessment and come in for on-site maintenance if needed.

"Across our industry, there are a lot of efforts and activities around ‘work anywhere’," said Goryl. "They're working remotely and traveling, and it’s more of a distributed workforce. This technology can better enable them with information on how to prioritize their time with systems, where they need to go to work, and what they have to address."

A focus on value going forward
When asked how X-ray tubes and service will evolve over the next decade, most experts agree that lowering costs will be a primary focus. This is largely due to the major cost pressure situation in the healthcare market.

“It will be more and more important to manage cost while maintaining value,” said Dunlee’s Pieper. “On one side we have increased patient demand and on the other side there is the continuing staff shortage.”

Chronos’ Fitzgerald thinks that cost-effective tube solutions are the answer to this problem. That could take the form of a lower initial cost of the tubes, longer lifetime or both.

Richardson Healthcare wants to make tube use and installation as easy as possible, according to Olsen, so that hospitals with in-house maintenance teams have the option of supporting their own equipment. The company hopes this will ultimately help reduce the cost of healthcare.

A cold cathode future?
Over the last 125 years or so, the basic principles behind X-ray tube technology have remained fundamentally the same. There have been advancements along the way, but nobody has reinvented the wheel. Today, that may be changing. New tube technology is in development that could make it much smaller and require less energy than conventional tubes. If it succeeds, it could signal a paradigm shift in access to imaging around the world.

Conventional tube technology operates using thermionic emission, but Nanox Imaging Ltd.’s new X-ray tube runs on cold cathode technology. Instead of being electrically heated by a filament, this new approach digitally generates electrons.

“Purely from an intellectual perspective, before seeing exactly how it could work, it sounds like a really good idea,” said ECRI’s Launders. “You can make things a whole lot less expensive because any time you make a device with moving parts like liquid metal bearings, the device is going to wear out.”

Nanox claims that their technology can avoid a few of the main causes of tube failures. Filament burn wouldn’t be a problem because a silicon chip is used instead of a metal filament, and anode cooling requirements can be lowered because two of these fast, low-cost tubes can be used instead of a single standard tube.

“Their tube is like what an LED is to a lightbulb — LED has now pretty much replaced regular light bulbs,” said Launders. “The company is hoping that their solid-state X-ray device will basically make regular X-ray tubes obsolete.”

In April 2021, Nanox received FDA clearance for its Nanox.Arc single-source digital X-ray system, which leverages the company’s digital X-ray tubes to generate 2D CT and tomography scans. The company is touting the system as a less expensive alternative to conventional X-ray systems.

“At an atomic level, it looks like it makes sense, but we need to see the full product to see if it will really perform,” said Francisco Rodriguez-Campos, senior project officer at ECRI.

There is a long road ahead for Nanox if it plans to replace conventional X-ray tube technology.