The image quality of the C-arm gets worse the more you use it? The cause may be the decay of the tube.


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 the C-arm machine is a normal decay, and then the after-sales engineers to adjust the C-arm machine is good. So why is the image quality of some C-arm machine will be the more you use the worse it is? Here’s a look at the professionals’ C-arm machine analysis.

The cause of image quality degradation in the C-arm comes from two sources: the detector and the bulb tube.

Detectors, whether flat panel detectors or image intensifiers, are supplied by large manufacturers, and when applied to small c-arms, the cumulative dose over the entire 10-year lifecycle is much lower than the maximum dose allowed over the lifecycle of the detector, and therefore the detector basically does not suffer from image quality degradation due to sensitivity degradation.

The one remaining possible source of attenuation is the tube. Possible sources of tube 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 low

National standards provide for the accuracy of the kV range is 10%, that is, a nominal output high voltage 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 high-voltage design of the bulb and the oil injection process, if the use of the full amount of kV may lead to easy discharge of the bulb, so artificially regulate the kV value at 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 the 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.

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

Tube is the C-arm and other medical imaging equipment core components, but see unfortunately, most of China’s medical imaging equipment manufacturers, do not have the core components C-arm tube 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 tube, high-voltage generator independent research and development production and manufacturing capacity. Since 2020, Perlove Medical’s brand of C-arm and mobile DR equipment has been recognised by many customers and has a leading market share.


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