The world’s first phased array CT becomes the most powerful “scout” of the lungs
The world’s first phased-array CT has become the lung’s ultimate “scout.”
A high-precision “camera” can help doctors detect lung nodules smaller than 2 mm and accurately distinguish between benign and malignant nodules, while also helping patients avoid unnecessary surgery and over-medication. This is the world’s first phased-array CT independently developed by a Chinese company. On August 12, this phased-array CT entered clinical trials at Ruijin Hospital affiliated with Shanghai Jiao Tong University School of Medicine, marking a revolutionary leap forward in the development of global CT technology.
Notably, Beijing Nanovision Technology Co., Ltd. (hereinafter referred to as “Nanovision”) independently developed and fully domestically produced the device’s core components, including the detector, high-voltage generator, and tube. “Phase-array CT technology is a new breed in the field of CT imaging equipment, and all core components are independently developed. We are navigating uncharted territory, with no homework to copy,” said Cao Hongguang, Chief Scientist of Nanovision, with a firm tone.
Subverting Traditional CT Technology
“The traditional mechanical rotation architecture is equivalent to mounting one or two cameras and a light source on a gantry, rotating around the body at high speed to take images. Phased array CT, on the other hand, uses a ring of light sources and cameras arranged on the gantry,” Cao Hongguang explained to reporters when explaining the principles of phased array CT architecture.
The traditional CT system’s frame is mechanically rotating, with the gantry rotating at high speed around the body. However, high-speed rotation generates enormous centrifugal forces, and based on current materials science and engineering, the performance of traditional spiral CT has reached its physical limits.
The optical rotation mode of phased array CT is a radical departure from the traditional mechanical rotation model. The gantry utilizes a dual-ring design combining a “detector array” and a “scanning beam source array.” Twenty-four tubes are evenly arranged on the outer periphery, forming a radiation source ring, while 64 photon flux detectors are located on the inner periphery, forming a detector ring. The radiation source rings alternately emit X-rays under precise exposure control timing, which are then received by the corresponding detectors. By replacing mechanical rotating structures with precisely timed pulse exposure, the physical limitations that restrict CT scanning speed have been successfully overcome.
In clinical applications, phased array CT can capture ultra-high-definition medical images of the human body, increasing the pixel count of each image from 512×512 in traditional CT to 3072×3072. Compared to traditional spiral CT, this achieves a 64-fold increase in spatial resolution, a 3-fold increase in temporal resolution, and a 144-fold increase in the amount of information per scan.
“This is like upgrading from an ordinary telescope to the Hubble Space Telescope,” said Cao Hongguang. “Phased array CT can help doctors visualize the secondary pulmonary lobule in living humans, the smallest functional area of the human lung. This is the first time in the world that such a small unit has been visualized using CT equipment.”
Achieving Technological Leadership in CT
To overcome the limitations of traditional CT’s small pixels in clinical medical imaging applications, Nanovision overcame numerous obstacles and independently developed key technologies, including photon flux detectors, distributed X-ray source arrays, and sparse angle imaging algorithms. The independent design and development of the photon flux detector, in particular, broke through the bottleneck of traditional CT detector reliance on imports.
Traditional CT detectors are first-generation integrating detectors, while the highest-end product for mechanical scanning CT is the second-generation photon counting detector. As early as 2012, the Nanovision team developed photon counting detectors. However, neither integrating nor photon counting detectors could meet the requirements of phased array CT. Therefore, Nanovision embarked on the challenge of developing the more challenging third-generation detector—the photon flux detector.
“It would be no exaggeration to say that photon flux detectors have hundreds of technical challenges,” Cao Hongguang explained. One of the challenges of photon flux detectors is the integration of three technologies: the photosensitive chip, analog technology, and digital technology. The chip must first be fabricated from scratch, and then crystal growth can be performed on this chip. The crystal growth process alone involves dozens of challenging steps, requiring companies to gradually explore the process themselves.
What crystal materials are suitable for detector applications? How are these crystal materials attached to the chip? Furthermore, crystal growth requires highly sophisticated equipment, which the company also had to design from scratch. After overcoming numerous challenges, Nanovision’s independently developed photon flux detector captured its first X-ray image in early 2016. This breakthrough laid a solid foundation for the subsequent development of phased-array CT.
The successful development of this phased-array CT marks the first time that a Chinese high-end medical equipment company has achieved full independent control over key CT technologies, completing a historic leap from a technological follower to a leader. Nanovision continues to explore ways to produce even clearer medical images with phased-array CT. “We are developing the next generation of phased-array CT, which will achieve microscope-like resolution, enabling doctors to visualize pathological images using CT equipment,” said Cao Hongguang.