Ever since Wilhelm Röntgen first photographed the bones in his wife’s hand, the X-ray tube (then a Crookes tube) has been a critical and fundamental component of medical imaging. We depend on radiation for a range of vital imaging exams including CT, radiography, fluoroscopy and mammography — and to generate that radiation, we depend on X-ray tubes.
 
Varian Medical Systems is one of the biggest manufacturers of X-ray tubes, producing between 22,000 and 25,000 of them every year. Mark Jonaitis, general manager and vice president of its X-ray tubes business, says there is a global X-ray tube market, but the demands are very different from one region to the next.
 
In some regions, breast cancer screening is just now becoming available, he says. In others, mobile C-arms are developing capabilities that may displace high-end cardiac and surgical suites. All of these changes are coinciding with a trend toward digital imaging and easier image acquisition and storage. Heather Funk, senior manager of marketing and business development at Dunlee, expects X-ray tubes to experience modest growth under the current economic circumstances.
 
Her company, a division of Philips Healthcare, has a rich history in tube design, research and manufacturing. That growth seems to be something independent of imaging modalities that have emerged over the last 50 years or so, like MR and ultrasound. Tom Spees, vice president of sales at Richardson Electronics Healthcare Division, calls these “supplemental support technologies.” His company is an industry leader in replacement tubes, a market that is expected to grow as radiography and CT extend their reach into new frontiers.

Developed markets reduce dose, increase sales
In established markets like North America and western Europe, it’s less about having access to X-ray systems than it is about having access to high-value systems with better functionality and lower dose to the patient. “For CT, it means that the majority will be 16-slice systems where detector size is a major cost driver,” says Jonaitis.
 
Finding ways to lower the dose not only benefits the patients and technologists — but the glassware itself. “Using dose reduction software enables the X-ray tube to be used in a less harsh way, with the same image quality results,” says Funk. That means longer tube life while decreasing the downtime of the scanner due to tube failures. New hardware and software are becoming available that drive dose levels lower than were once thought possible, says Jonaitis.
 
For mammography, photon counting enables micro-dose exposure, but comes at a higher cost. For CT, iterative construction software is starting to take off. Some experts anticipate that anode end grounded (AEG) X-ray tubes will become more common. AEG tubes (which are single ended, or unipolar) allow for considerably higher power than conventional (bipolar) tubes, with smaller size and less heat.
 
Another key benefit of AEG tubes is that there is less “off focal radiation,” which allows for a harder beam, or less electrons rebounding and striking the target at areas other than the focal point. Stopping those stray electrons from generating unnecessary photons means less heat is generated, less blur from misplaced radiation in the image, and less non-useful radiation hitting the patient.
 
CT systems are replaced in the interest of meeting new safety protocols, which means tube demand overall could go up, says Spees. To be compliant with MITA’s XR-29 standards, for example, an estimated one-third of the installed outpatient systems will need to be replaced. Funk points to the customers who are compliant with regulations and mindful of the bottom line, which has become increasingly important with health reform. “We see customers holding onto their current scanners longer which, in turn, will have a positive impact on replacement tube sales into the future,” she says.
 



More manufacturing in burgeoning markets?
As new markets emerge globally for X-ray tubes, those regions face tough decisions about building locally or importing. As Jonaitis points out, many countries do not like to see government funding going overseas and create regulatory barriers that make importation difficult. In some regions, an alternative might be to use government funding to create a domestic supply, but building X-ray tubes is no small task. Their production is a sophisticated process that does not lean heavily on manual labor (or create a flood of jobs).
 
Funk says it is more likely that existing X-ray tube manufacturers will expand either parts or full production capabilities in developing countries to be closer to those customers. Jonaitis points to Brazil, China and Russia as three countries where that prediction is already proving to be accurate. Much of the cost of X-ray tubes is derived from materials and overhead, but Spees says the technical barrier is the most significant. High-end CT tube manufacturing comprises competency in mechanical engineering and thermal management of stress and materials.
 
“At the functional core is high-voltage vacuum technology, where cleanliness is imperative,” says Spees. Instead of getting involved in the manufacturing process, Spees predicts many of the emerging markets will turn to reliable replacement tube vendors to keep their systems operational. “In general tubes will cost less as manufacturers are driven to compete in emerging markets,” says Jonaitis. “This level of cost awareness will have an impact on the overall market and allow more competitive pricing even on the high end of performance.”
 


Hurdles to in-house maintenance
For providers that service their equipment in-house, X-ray tubes have traditionally been a source of some trouble. The installation process can be very involved. However, for many systems, radiographic and mammography, for instance, that is beginning to change. As Jonaitis puts it, “simplicity is king.” But that’s not necessarily the case with CT, where he says dosing concerns have given way to some highly sophisticated calibration techniques.
 
Spees has a different perspective on in-house servicing. “The major OEMs prefer that other service organizations, including in-house, don’t work on their equipment because maintenance service is a significant amount of their annual revenue, and an even more significant amount of their margin,” he says. For that reason it’s not uncommon for OEMs to artificially create “barriers” to prevent others from doing maintenance, including changing the X-ray tube, he continued. Aside from 24/7 customer service, Funk’s company offers Dunlee Academy, an online tutorial to help guide technicians through the installation process step by step, complete with pictures and videos.
 



What’s next?
“Advanced detectors and more sensitive receptors, along with image processing algorithms allowing the image to be created with fewer photons to the receptor, should be encouraged and strived for,” says Spees.
 
Funk says Dunlee concentrates on ways to keep costs down on its tubes, and the best way they’ve found to achieve this is by producing reliable glassware. “By improving our X-ray tube product quality we extend the life of our tubes, resulting in lower overall costs.” Ultimately, providers need to keep their sights on the needs of younger patients. As people live longer lives, that exposure to radiation has more potential to cause later damage and that danger is no better illustrated than in younger patients who are still undergoing fast cell growth, says Jonaitis.