(a) high-voltage generator
It is for the generation of x-rays to provide a stable DC high pressure, the size of its high pressure value directly affects the change of x-ray energy value, and x-ray energy and absorption coefficient is extremely close, because only in the case of x-ray energy is stable in order to accurately reflect the object being scanned by the absorption coefficient of x-rays, so the stable high pressure is one of the important foundations of the CT Therefore, stable high voltage is one of the important foundations of CT imaging quality. The high voltage system applied in any type of CT machine must adopt high-precision feedback stabilization measures to meet the technical requirements of the CT machine.
(B) x-ray tube
CT machine with x-ray tube and general x-ray machine with the same x-ray tube, are highly vacuum diode, divided into fixed anode and rotating anode two. Fixed anode x-ray tube can only be used for slow scanning speed, the need for power flow is small, the 1st and 2nd generation of CT machines; rotating anode x-ray bulb tube for fast scanning speed, the need for power flow of the machine, the heat capacity of this x-ray tube is also very large, such as the 3rd and 4th generation of CT machines, which need to be in a very short period of time (1s or a few seconds) to produce enough energy, and requires a higher value of the current. As the x-ray tube in the occurrence of x-rays to produce a large amount of heat energy, its rotating anode can make the heat evenly distributed throughout the circular target surface, on the one hand, play a protective role, on the other hand, helps to dissipate heat. In the x-ray tube structure, molybdenum target anode x-ray tube target surface of its heat resistance is higher than the ordinary anode x-ray tube target surface.
(C) cooling system
For fixed anode x-ray tube using oil-cooled cooling system can meet the requirements. For rotating anode x-ray tube, often need to quickly dissipate a large amount of heat, more oil - air cooling, that is, the heat of the anode target surface is first transferred to the surrounding oil, and then through the high-pressure oil pump to the radiator, radiator cooling fan, so that the heat dissipated into the air, after cooling the oil and then circulated back to the x-ray tube, in order to control the temperature of the x-ray dome tube. The oil is then circulated back to the x-ray tube to control the temperature of the x-ray bulb. As the 3rd and 4th generation of CT machine scanning time is relatively short, and the scanning interval cycle is also short, so in a short period of time to make a number of scans, the anode target surface of the thermal energy will increase exponentially, so there must be a good cooling radiator to ensure that the x-ray tube's continuous work. Nevertheless, in practice, will often need to wait for the x-ray tube heat to reach the next scanning temperature requirements before continuing.
(D) before the collimator
This part is also known as the focusing system, which has the ability to remove scattered rays, can make x-rays arranged in a beam, but also adjust the thickness of the scanning thickness of the layer.