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The development history of CT tube
- 2020-11-27-

CT tubeThe development process of the CT tube is basically the same as that of the tube used in ordinary X-ray machines, and there are two types of fixed anode tube and rotating anode tube. Roentgen discovered X-rays while experimenting with cold cathode tubes. The tubes he used at the time were called "Crookes", which were sealed glass tubes containing 2 electrodes (anode and cathode) and a small amount of gas . After the Crooks tube is connected to high voltage, the gas in the tube is ionized, and the electrons are accelerated to hit the target surface to generate X-rays. The tube current and tube voltage of the Crux tube cannot be adjusted separately, and the power is small, the life is short, and the X-ray quality is high. unstable.

In 1896, CHFMuller created the world's practical X-ray tube, which is a very simple tube with no clear focus. The image is very blurry. In the same year, Muller created a focal X-ray tube, also known as the Muller tube. This tube put a concave mirror through the cathode to focus the X-rays at one point, and the two ends were connected to each other. After the current, the cathode emits a stream of electrons that hit the anode, producing X-rays.

In 1913, Coolidge created a high vacuum hot cathode fixed anode tube (stationary anode X-ray tube), also known as Coolidge tube.CT tubeThe vacuum in the tube is high, electrons are emitted from the hot cathode, and the high voltage voltage applied to the anode and cathode 2 ends accelerates to hit the anode target surface to generate X-rays. The Coolidge tube only needs to change the working temperature of the cathode to adjust the size of the tube current. In addition, Coolidge The tube current and tube voltage of the tube can be adjusted separately. In 1923, the double focus fixed anode tube was successfully developed, so that one tube has two different focus sizes and power characteristics at the same time. Because the anode target of the fixed anode tube is fixed and not fixed. A moving, high-speed electron current bombards the fixed position of the anode target, which has the characteristics of low power and large focus. At present, the fixed anode tube is only used in low-power mobile X-ray machines or dental X-ray machines.

In 1927, Shengli developed a rotating anode X-ray tube. The high-speed moving electron beam is ejected from the cathode which is deviated from the central axis of the tube and bombards the rotating target surface. Because the high-speed moving electron beam bombards the target The heat generated by the surface is evenly distributed on the rotating annular surface, the area bombarded by the electron beam is greatly increased due to the anode rotation (the actual focus and spatial position remain unchanged), and the heat distribution area is greatly increased. Due to the rotating anode ball The tube has the characteristics of high power and small focus, and it has developed rapidly after its introduction. In the 1960s, the rotating anode speed reached 9000r\/min. In the 1970s, the metal shell rotating anode bulb appeared.

In 2003, Siemens introduced the Straton electron beam control tube. The strato electron beam control tube adopts the design of anode direct cooling, which can release up to 10 times the heat compared with the traditional CT tube. Fast cooling means that it can The device is lighter in weight due to the installation of a smaller anode, which further improves mechanical stability and achieves higher rotational speeds. In addition, the Straton electron beam control tube also has "flying focus" technology, which can record each scan from multiple angles For each projection, increase the sampling rate and greatly improve the clarity of the image.

In 2013, GE introduced a liquid bearing tube called Performix Plus, and in 2015 it launched a new Performix 40 Plus liquid bearing tube for the Revolution EVO CT. At the same time of high quality image, it not only reduces the noise during rotation, but also prolongs theCT tubeof service life.