The image quality of the C-arm gets worse the more you use it?


A hospital purchased a national brand of C-arm machine, found that the image quality will deteriorate after one or two years, the manufacturer explains that it is the normal attenuation, and then after-sales engineers to adjust it is good. So why is the image quality of some c-arm machine will get worse the more you use it? Here to see the analysis of the professionals

C-arm machine image quality

The reason for the decay of image quality of c-arm comes from two aspects: the detector and the bulb tube.

Detectors, whether flat panel detectors or image intensifiers, are provided by large manufacturers. When applied on small C-arms, the cumulative dose over the entire 10-year lifecycle is much lower than the maximum dose allowed in the detector’s lifecycle, so the detector basically does not suffer from image quality degradation caused by sensitivity decay.

The one remaining possibility for attenuation is the bulb tube. Possible sources of bulb attenuation are a lack of kV, a decrease in tube current (mA), or a decrease in dose with no change in kV mA. The following one by one analysis.

1, kV becomes low

The national standard provides a kV accuracy range of 10%, that is to say, a nominal output high voltage of 110kV C-shaped arm, according to national standards, the actual measurement to 110-110 * 0.1 = 99kV even if qualified. However, some manufacturers due to the integration of the high voltage design of the bulb tube and the oil injection process, if the use of the full amount of kV may lead to the bulb tube is easy to discharge, so artificially adjust the kV value in the lower limit. That is to say, the display kV is 110, the actual kV is only 99, and even once there is a slight change, the kV value is not up to 99kV, so the patient encountered with a slightly thicker body will not penetrate, resulting in poor images.

2、Low mA

mA is the tube current, mA slight changes or inaccuracies will lead to changes in image quality.

If a factory’s mA lack of closed-loop control, due to the non-linear relationship between mA and filament current, even if a little bit of mA regulation is accurate, with the temperature change and time change, mA will be more and more inaccurate, which will lead to the emergence of the so-called image quality attenuation problems.

In addition, if the manufacturer’s control of the filament is not accurate, the filament may be at a higher temperature for a long time, or each exposure will have a high current impact, the tungsten element of the filament will slowly evaporate, resulting in insufficient filament electron emission capacity, mA decline.

3, kV and mA unchanged, the dose becomes lower

If the manufacturer designs an integrated bulb, the kV/mA used exceeds the power that the anode target can withstand, it will cause the anode target surface to gradually hairy, forming small pits over time, resulting in rays can not be completely issued, ultimately resulting in no change in kV mA, but the dose will be substantially reduced.

To summarize: a properly designed C-arm machine will not experience image quality degradation during its life cycle. If there is image quality degradation, the engineer to improve the kV, or improve the mA is good, then the probability is the lack of closed-loop control caused by the drift; or the design of the unreasonable resistance resistance changes or filament evaporation; rotating anode bulb tube may also be the thermal management of the target surface damage caused by the unreasonable.

Ball tube is the core components of medical imaging equipment such as C-arm, but see unfortunately, at present, most of China’s medical imaging equipment manufacturers, do not have the core components of independent research and development production capacity. And as a mobile C-arm domestic leading manufacturers of Perlove medical, is one of the few domestic manufacturers of core components, currently has a balloon, high-voltage generator independent research and development production and manufacturing capacity. Since 2020, Perlove Medical brand C-arms and mobile DR equipment have been recognized by many customers and have a leading market share.


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