The advancement of science and technology has accelerated the development of medical care. CT(Computed Tomography), or computer X-ray tomography, features short scanning time and clear images. It is used in the examination of various diseases and is a commonly used medical imaging examination technique in clinical practice. During the epidemic, due to the timely, accurate, fast, convenient and clear imaging characteristics of CT examinations, chest CT examinations have become powerful tools for screening and diagnosis and treatment.
A CT machine is composed of an X-ray tomography scanner and a computer system. The former mainly consists of an X-ray beam generator and a CT tube, as well as a detector for receiving and detecting X-rays. The latter mainly includes data acquisition systems, central processing systems, tape drives, operation consoles, etc. CT uses an X-ray beam to scan a certain thickness of the inspected area. The X-ray passes through the detector and is converted into visible light. Then, it is transformed into an electrical signal by a photoelectric converter and converted into a digital signal by an analog-to-digital converter, which is input into a computer for data processing and image reconstruction to form a CT.
As one of the core components of CT equipment, the CT tube is a high-value consumable with high technical barriers. Its performance directly affects the inspection effect and service life of CT examinations. CT tube technology is highly challenging, involving multiple scientific fields, with complex processes and high manufacturing costs. In complex CT equipment, CT tubes are more prone to damage and malfunction as the number of exposures increases. With the development of technology and the diversification of clinical demands, the research and development of CT equipment is constantly evolving, such as spiral CT, wide-cone CT, dual-source CT, dual-energy CT, etc. This also puts forward higher requirements for CT tubes. On the one hand, the performance of the tubes needs to meet the requirements of high speed, high power, high clarity and low dose for CT imaging. On the other hand, the lifespan of the tubes should be longer and the cost lower.
A CT tube is actually a highly vacuum cathode ray diode capable of generating X-rays. The cathode is the filament that emits electrons, and the anode is the target material that withstands the bombardment of electrons. A 12V current is supplied to the cathode filament for heating, generating a concentration of free electrons. When a high voltage of 40-150KV is applied to the anode and cathode, the potential difference suddenly increases. Driven by the high-voltage strong electric field, the free electron beam in an active state strikes the molybdenum-based tungsten target at high speed from the cathode and undergoes energy conversion. About 1% of the electrical energy forms X-rays, which are emitted through the window. 99% of it is converted into heat energy and distributed by the cooling system.
This means that the CT tube needs to have a relatively high heat capacity. Generally speaking, the higher the heat capacity, the more heat it can carry, the longer the continuous exposure application time, and the corresponding longer the service life of the tube. The increase in heat capacity leads to higher demands for tube materials, anode rotating structures, etc. The heat dissipation rate of the anode target material should also be high. A high heat dissipation rate can effectively extend the scanning time. However, as the anode speed increases and approaches the physical limit, it is very difficult to further increase the speed. On the other hand, an increase in rotational speed means that the shorter the time the electron beam stays at a certain point, the greater the heat received by the target disk, that is, the greater the power. However, the local bearing faces greater challenges, generating more heat, accelerating wear, and also increasing noise.
CT examinations are radioactive, and the radiation levels vary for different parts of the body. The irradiation dose, time and interval affect the radiation dose. The interval between the examinee and the CT equipment cannot be adjusted, but it can reduce the dose and duration of radiation exposure during the CT examination. The faster the CT scan speed, the shorter the exposure time to radiation. The lower the radiation dose used, the less radiation there will be.
Earlier, the domestic CT market was monopolized by foreign brands such as Philips, Siemens and GE. Zhuhai Ruineng Medical has achieved the first domestic production of CT tubes, marking a historic breakthrough in "Made in China". With the intensifying of national policies, domestic enterprises are making vigorous efforts. Emerging companies such as the 12th Research Institute of China Electronics Technology Group Corporation, Shanghai United Imaging, and Kunshan Yiyuan each have their own strengths, gradually opening up a new scene for domestic CT tubes.
The diversified competition among domestic and foreign enterprises has accelerated the multi-point research and development of CT tubes, achieving remarkable results. The electron beam control tube, which incorporates electron beam filtering technology, can effectively filter out low-energy electron beams that have no effect on CT imaging and reduce the radiation dose of the rays. Liquid bearing ball tubes, liquid bearings mainly composed of liquid metal replace bearings centered on steel balls, with zero wear, zero vibration, and can provide a high heat dissipation rate. The anode extraction cooling technology was added to the CT tube, making the anode cooling rate and heat generation rate almost equal, and the tube could be cooled in time. Metal ceramic CT tube, which enhances the strength of the tube shell and improves the vacuum degree of the tube... Emerging technologies are springing up like mushrooms after rain, bringing fresh blood and injecting new impetus into the research and development of CT tubes.
With the implementation of the hierarchical medical system in our country, the demand for CT in the primary medical care market has increased, and the demand for CT tubes has also grown accordingly. Moreover, CT tubes need to be replaced regularly based on usage conditions. They are expensive and are high-value consumables with a broad market. At present, the domestic market relies on imports, and the level of domestic production urgently needs to be improved. There is great potential for CT tubes.