With the rapid development of science and technology and China's medical and health care, medical X-ray and CT machines have been popularized in China's municipal and county hospitals, high-grade multilayer spiral CT is also in the provincial and municipal key hospitals have been used. The bulb tube is the most expensive consumable core component of CT, with a purchase price ranging from more than 100,000 yuan to millions of dollars.
Scanning (especially the number of exposures enough balloon) often reported on the balloon failure, careful inspection and analysis of non-fatal faults in a timely manner to repair and eliminate the restoration of normal scanning, not only to reduce downtime, to ensure that a good social benefits, but also effective in extending the service life of the balloon, to create a good economic benefits. This paper combines the relevant information and their own experience in the work, talk about some of the problems of the ball tube, I hope to play a role in attracting jade. I hope that the experts and fellow teachers and friends to give correction.
1 The structure of the ball tube composition
Generally CT ball tube by the core, tube sleeve and matching oil cooling part of the composition, of which the core and the rotating anode, filament, core glass shell and other components.
2 Factors affecting the service life of the bulb
The factors affecting the service life of the CT bulb are as follows:
2.1 Installation and debugging of the bulb
The bulb should be strictly in accordance with the requirements of the bulb's technical parameters of the filament voltage, current, etc. to adjust, and to make a good before and after the location of the position, kV, mA, etc. calibration, regular testing of the parameters and timely adjustment. Adjustment. Otherwise, not only affect the life of the tube ball, and affect the image quality, and even artifacts.
2.2 Scanning technology conditions
The main conditions are: kV, mA, scanning time (the time required for one week of rotation of the tube ball), layer thickness, pitch, scanning range, reconstruction mode and other parameters.
2.3 The working condition of the cooling system of the tube ball
Most of the cooling system of the CT balloon adopts the way of air cooling and oil cooling of the balloon, so it is extremely important to pay attention to observe the efficiency of the cooling system of the tube ball. The most important work is to regularly clean the dust on the filter and the radiator dust, so that the flow rate of the wind is always kept in the best state to improve the cooling efficiency.
2.4 The quality of the tube ball itself
The rational use of the tube ball is mainly reflected in the control of the scanning heat capacity, without affecting the quality of the image, according to the scanning requirements and the actual human body scanning image, appropriate reduction of the MAS; helical scanning patients with axial scanning patients with the examination, according to the different parts of the adjustment of the pitch; regular check of the power supply parameters of the tube ball and the cooling system work. The power supply parameters of the tube ball and the working status of the cooling system are checked regularly. Through the above methods, the work routine of each CT unit is formulated and required to be strictly implemented by the operators. After more than two years of observation, the average service life of the tube ball has been greatly improved.
3 CT ball tube routine maintenance and maintenance
3.1 external three-phase power detection. Including three-phase power supply phase, phase spoke balance stability, and spoke equalization, no phase shift and ground resistance and grounding good or not.
3.2 Eliminate rats and cockroaches and other animals. As they bite off the wire, contamination of the circuit board, causing fires are not uncommon.
3.3 temperature and humidity of the room. Temperature is too high or too low, electronic circuits can not work properly. The working environment is too dry, easy to cause static electricity; working environment is too wet, easy to oxidize dust and other humidity caused by short circuits. Usually the working environment to maintain the temperature between 20 ~ 300, temperature change rate ≤ 30C / h, humidity 75%, humidity change rate in ≤ 5% / h.
3.4 CT on the detection of various operating parameters of the bulb, including CT bulb kV, Ma, temperature and so on.
3.5 The contact between the high-voltage cable and the bulb tube is good, and the contact parts are free of impurities, and it is checked once every two years.
4 common faults and maintenance of the bulb
For the bulb and its high-pressure caused by the failure phenomenon, according to the composition of our roughly summarized as follows:
4.1 filament problem general filament open circuit or half-open circuit
Failure to perform: add high-pressure does not expose the current, no tube current or current instability, prompting the filament is open-circuit (or Low mA), the filament is open-circuit in checking the In the case of checking the filament and the normal supply, measurement of the filament resistance open-circuit for the bulb tube filament open-circuit. It should be noted that: sometimes the filament is in a half-open state, when not pass, when the work of heating caused by open-circuit, and power off when the cooling is connected, often leading to misjudgment, need to be repeatedly identified.
4.2 core vacuum drop or core glass shell broken
Failure performance: view the fault code is generally prompted by overload alarm. One situation is that the core after long-term use of filament evaporation, target surface damage gasification, core vacuum is reduced; the second is not used for a long time, the core of the core of the gas infiltration, or core shell aging cracked, there is oil infiltration, high temperature carbonization of the resulting gas, the core vacuum is reduced.
4.3 Rotating anode does not turn
Fault performance: the alarm shows that the rotating anode (Rotor) failure. This fault generally has the following two causes: first, the rotating anode stator coil damage (open or short circuit); second, the rotating anode rotor jammed or bearing wear and tear clearance is too large, the distribution of the magnetic field after energization is not balanced and suction death.
4.4 High-voltage fire in the tube sleeve
This type of failure occurs when the alarm shows overload. High-voltage cable plug loose or with the socket between the sealing insulation is reduced or high-voltage plug cracked, can be caused by intermittent firing, serious overload alarm and interrupt the scanning, firing reconstruction of the image of the thin strip of interference lines. Pull out the high-voltage cable plug inspection, can be found in the plug, socket has obvious discharge charcoal burn marks, and accompanied by irritating odor. Clean up with anhydrous alcohol and gauze, and then re-seal the high-voltage rubber pad, high-pressure silicone ester or insulating oil can be returned to normal.
4.5 tube core internal fire
The failure is manifested as: a start exposure immediately overloaded, prompted by the overload (Over mA), generally occurring in the exposure of more counts of the bulb tube. Sometimes after reducing kV, mA can still scan, but the image is poor. After long-term use of the core filament evaporation, target surface damage gasification, core vacuum is reduced; or because the glass shell in the high temperature oil pressure cracks, core gas infiltration; or core shell aging cracked, oil infiltration, high temperature carbonization of gas, core vacuum decreased, the dome tube scrap.
4.6 tube sleeve oil leakage
Slight oil leakage does not affect the work, more oil leakage, there will be bubbles in the tube sleeve, scanning will be overloaded (set of fire). Appearance inspection can be found, careful observation can be found in the oil leakage parts, mostly for the pipe joints at the loose or gasket aging caused. Tighten the joints or replace the gasket can return to normal.
4.7 Balloon overheating
Failure performance: scanning waiting for a long time to cool down, prompting the temperature or oil pressure failure, most of the balloon oil circulation cooling system failure. Specifically can be divided into:
4.7.1 radiator grid is stuffed with dust, poor heat dissipation, after clearing the dust normal.
4.7.2 Cooling fan does not turn, mostly winding damage or bearing stuck. Replace the fan.
4.7.3 Circulating oil pump bad. Oil pump motor bad or bearing stuck or oil pump damage, repair or replacement.
4.7.4 Oil filter blockage. Insulating oil impurities or foreign matter, cleaning and oil can be normal.
Balloon fault judgment related factors are more, how to distinguish clearly whether the balloon problem is more complex, we can be subdivided into:
(1) high-voltage control circuit failure; (2) high-voltage inverter (trigger) failure; (3) anode rotary controller failure; (4) anode inverter trigger failure; (5) filament circuit failure; (6) high-voltage cable breakdown; (7) high-voltage oil tank Feedback resistance abnormality; (8) high-voltage tank within the silicon stack breakdown, etc..
The rational use of the tube ball is mainly reflected in the scanning heat capacity control, without affecting the image quality, according to the requirements of the scanning part and the actual human body scanning image, appropriate reduction of the mAS; regular inspection of the tube ball power supply parameters and the cooling system status, through the above methods to develop the CT of the work of the routine requirements of the operator to strictly implement, can make the CT life has been greatly improved.