Breaking the overseas monopoly on liquid-metal‑bearing X‑ray tubes! ZhiShu Technology has achieved complete independent R&D and in‑house production of CT X‑ray tubes.

The X-ray tube, a core component of CT scanners, can be regarded as the lifeblood of the hundred-billion-dollar medical imaging market.

Its strengths and weaknesses not only to a certain extent determine the overall performance of the CT system, but have also long been regarded as pivotal in narrowing the gap between domestic offerings and imported brands in the high-end segment.

However, due to the technical complexity and stringent manufacturing requirements of key CT components such as the X-ray tube, coupled with the need to customize most production equipment, this critical component has yet to achieve full domestic production. For a long time, most Chinese imaging manufacturers lacked the capability to independently research, develop, and manufacture core components, leaving the core parts of high-end domestic products predominantly imported.

In April this year, Beijing Zhisu Technology Co., Ltd. (hereinafter referred to as “Zhisu Technology”) achieved a major breakthrough by obtaining the first medical device registration certificate for a domestically produced liquid-metal‑bearing CT X‑ray tube, and has now attained mass‑production capability. Today, the company’s independently developed liquid‑metal‑bearing X‑ray tubes have also entered the pre‑installation stage and are poised to undergo certification for integration into complete systems.

According to reports, Zhisu Technology has established a comprehensive design and R&D system covering all stages—from design and materials to manufacturing, assembly, and reliability testing—and has developed full-fledged capabilities for product development, iteration, and production.

As the first domestic company to develop a liquid-metal‑bearing CT tube, Arterial Network recently conducted an exclusive interview with Hu YinFu, founder of ZhiShu Technology, to address key issues such as trends in CT tube technology and critical technical milestones, as well as the pivotal challenges in R&D for liquid-metal‑bearing tubes.

Breaking through liquid-metal bearing technology for X-ray tubes,

Several CT X-ray tubes currently under development are poised for approval.

From the perspective of the evolution of X-ray tube technology, traditional CT tubes typically employed ball bearings. However, with the advent of liquid-metal bearing technology in the 1990s, this innovation gradually supplanted ball bearings and became the dominant choice for high-end CT systems during the first two decades of the 21st century.

Compared with conventional ball bearings, liquid-metal bearings offer at least four key advantages:

(1) Significantly enhances the heat dissipation rate. Specifically, under the same physical thermal capacity of the target disk structure, the effective thermal capacity can be greatly increased.

(2) Liquid-metal sliding bearings can withstand frame‑rotation centrifugal forces of 30–40 g, enabling faster gantry rotation and higher imaging rates, which offers a significant advantage for cardiac imaging.

(3) Since, during operation, the bearing core does not come into direct contact with the bearing outer race, wear is minimal, and the service life is at least more than twice that of ball bearings.

(4) Liquid-metal sliding bearings have no contact, resulting in completely silent operation.

With the continuous maturation of liquid-metal bearing technology in recent years and the decline in mass-production costs, liquid-metal bearings are no longer confined to high-end CT scanners; they are now expanding into mid-range models. Consequently, their application scenarios and market potential have become increasingly broad.

However, the production and manufacturing of key components for liquid-metal‑bearing X‑ray tubes involve more than 30 process steps. The critical technical challenges span design, materials, machining, welding, vacuum technology, surface treatment, precision assembly, and other areas, with breakthroughs in these core technologies proving particularly difficult to achieve.

By integrating expertise in three-dimensional tube design—leveraging tools such as Inventor, SolidWorks, and Pro/E—electro‑optical design and simulation using software like OPERA and CST, electromagnetics, design and simulation with CST and Ansys, structural mechanics and thermal‑fluid dynamics simulation employing Ansys and Fluent, as well as rotor dynamics modeling, Zhishu Technology has, within just three years of its founding, achieved breakthroughs in key technologies for liquid‑metal‑bearing X‑ray tubes, thereby breaking the technological monopoly held by foreign manufacturers in this field.

With the continuous advancement of Zhisu Technology’s manufacturing processes, the first‑pass yield for its liquid‑metal bearing CT tube production has reached over 90%.

Hu Yinfu shared Zhishu Technology’s bearing manufacturing process with Arterial Network, stating: “Take the key component—liquid-metal bearings—as an example. Their production involves a complex array of process steps, requiring solutions to numerous critical technical challenges, and each step is closely interconnected. You must evaluate the overall process performance as a whole, rather than assessing the feasibility of any single step in isolation.”

During the process‑stabilization phase for our ZS502L liquid‑metal bearing, we underwent nearly dozens of iterative refinements and optimizations. As a result, process stability has improved dramatically: whereas in the early stages only a handful of samples could pass testing, today batch production achieves a first‑pass yield exceeding 90%.

Looking ahead, we aim to further narrow the gap with companies such as GPS—leaders in the mature development of CT X-ray tubes—through targeted process optimizations, and ultimately achieve domestic technological breakthroughs in CT tube technology via independent innovation.

With nearly 20 years of R&D experience in the field of vacuum electronics, the company will continue to strengthen its position in the core components segment for CT technology.

As a core component of CT scanners, the development of X-ray tubes is not only characterized by lengthy process flows, substantial capital investment, extended R&D cycles, and slow returns, but also represents a quintessential multidisciplinary field. Consequently, CT tube R&D places exceptionally high demands on the overall competence of the team—requiring a group that possesses deep expertise in process optimization and iterative refinement, conducts rigorous research and design, meticulously examines every technical detail, and rigorously controls each operational step.

Hu Yinfu studied at both Wuhan University and Tsinghua University, where he earned a Ph.D. in Physical Electronics. Following graduation, he served as Vice Chair of the IEEE China Council and as MDC Chair of the IEEE Beijing Section. He has published more than 50 academic papers in domestic and international journals and conferences, and brings nearly 20 years of experience in research and development, manufacturing, and management within the field of vacuum electronics.

“As engineers trained in vacuum electronics, we can’t help but feel a lingering sense of frustration when confronted with foreign‑imposed technological bottlenecks. In the medical field—where patient safety and health are at stake—being able to tackle critical technical challenges and advance domestic industry development brings our entire team an immense sense of accomplishment and fulfillment.”

“I’m incredibly proud of our R&D and process engineers—they’re hardworking and resilient. In the course of optimizing and iterating CT X-ray tube manufacturing technologies, it’s commonplace for the Zhisu Technology R&D team to work through the night. They’ll set up a camp cot next to their computers; when they get tired, they’ll take a short nap on it before getting back to evaluate the results of their process improvements—this has become an almost routine occurrence. So if I had to name the secret to overcoming R&D challenges, I’d say it’s our unwavering determination never to give up in the face of these technical hurdles,” said Hu YinFu.

Currently, Zhishu Technology has obtained medical device registration certificates for two of its products, and in 2022, five additional CT tube prototypes under development are expected to receive approval one after another. Its independently developed ZS402L CT tube, intended for integration into a domestic 32‑row CT system, has already passed type testing and on-site quality‑system assessments, with registration anticipated by October 2022. This will make it the first complete CT system to feature a domestically produced liquid‑metal bearing CT tube.

According to reports, ZhiShu Technology is currently expanding its product pipeline. China’s first production and manufacturing center for liquid-metal bearings is also set to become operational this year, with a designed capacity of 2,000 sets per year. Meanwhile, its pipeline of CT tube products under development is expected to cover mainstream models on the market.

Meanwhile, the company has established in-depth collaborative relationships with enterprises such as Kuanteng Medical, Sinovision, Kaiying Medical, Boying Medical, and Wandong Medical, encompassing product customization, new‑product development, and joint registration of complete systems. In addition, it has laid the groundwork for future cooperation with United Imaging Healthcare, Neusoft Medical, and Mingfeng Medical.

Looking ahead, supported by favorable policies, technological advancements, equipment upgrades, and capital investment, Zhishu Technology will continue to ramp up its R&D efforts. At the same time, through sustained dedication, the company aims to provide domestic CT system manufacturers and third-party service providers with a full range of cutting-edge CT X-ray tubes, striving to achieve complete coverage of all major liquid-metal‑bearing tube models in the market within three years.

By leveraging high cost-performance, we aim to establish a competitive edge and work alongside domestic enterprises to accelerate the localization of CT X-ray tubes. At the same time, we will continue to strengthen the autonomy and controllability of our industrial and supply chains, thereby truly achieving the goal of independent control over core component technologies.

Achieve a breakthrough from “0” to “1,”

The X-ray tube industry is poised for rapid growth.

In 2018, the “Catalogue for the Licensing and Management of Large Medical Equipment (2018)” redefined the procedures for allocating large imaging equipment: CT scanners with 16 rows or fewer no longer require administrative approval; and the authority to regulate the procurement of single units or sets of large medical devices priced between RMB 10 million and RMB 30 million, as well as CT scanners with 64 rows or more, was transferred from the National Health Commission to the provincial health commissions.

Following the policy rollout, primary-level medical institutions began to procure 16-slice CT scanners on a large scale, driving substantial growth in both the original‑equipment and replacement markets for X‑ray tubes. Meanwhile, demand for high-end CT systems has become increasingly diversified.

On the one hand, as the annual revenues of tertiary hospitals across the country have risen sharply, the financial burden of acquiring CT scanners has eased considerably. On the other hand, the emergence of independent imaging centers has sparked a wave of high-end CT‑scanner purchases. By the end of 2019, the total number of CT scanners with 64 or more detector rows in China had nearly doubled.

Today, China’s X-ray tube market has achieved a breakthrough from zero to one, and a growing number of leading manufacturers are emerging in the development of core components for imaging equipment.

Finally, Hu Yinfu stated: “As the localization of high-end medical devices gains momentum, achieving complete domestic production of core components for imaging equipment is of paramount importance. Although CT X-ray tubes represent a highly niche segment within the medical device industry, their market size is far from insignificant. According to our estimates, the global market for CT X-ray tubes totals US$8 billion, while the domestic market in China reaches RMB 8 billion. Among all high-value medical consumables, its market size ranks just behind orthopedics and vascular intervention.”

Looking ahead, as the domestic market for complete CT systems continues to expand, bolstered by supportive policies and industry growth, X-ray tubes, high-voltage generators, and detectors are poised for rapid development. Zhishu Technology will also broaden its product portfolio, spanning materials, supply-chain capabilities, and a diverse array of tube technologies.