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Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/13/2013 3:49 AM

I work as Insurance Surveyor. I have a Claim where I have to deduct proper depreciation for the failed X-Ray tube of a CT Scan machine. In the CT scan machine the manufacturer gives a counter having Milli ampere second as the unit. I need to know the normal life of a Rotating Anode type X-Ray tubes for CT scan machine. Who can give the Mean Time Before Failure for such tubes? The manufacturers support is helpful but how to get ?

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Guru
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#1

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/13/2013 4:38 AM

You said: Who can give the Mean Time Before Failure for such tubes?

Well, the tube manufacturer can, and probably has, MTBF data for their tubes used in various makes and models of CT Scan instruments (don't call them machines!)

Then you said: The manufacturers support is helpful but how to get ?

If you say it is helpful, that implies that you have talked with them and are somewhat satisfied. Then you imply that you can't get the support.

Which is it? Are you getting help from the manufacturer or not? Have you seen website data, but not been able to reach someone by phone?

You are not being very clear about the details of the investigation. I am assuming that English is not your primary language. If this is the case, finding someone knowing (Hindi or Farsi - I am guessing) and English and that can review and edit and/or translate your dialogue between you and the tube manufacture and this forum, would be a big help.

Mike

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#2

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/13/2013 8:03 AM

This is made more complicated by the fact that the life of the tube is strongly dependent on the anode current. If high currents are used frequently, the tube life will be shorter.

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Guru

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#3

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/13/2013 5:10 PM

The only ETHICAL way for you to determine the MTBF is with a letter from the manufacturer if the device.

Or a paid consultant with standing in the courts of your country.

Anything else is just hearsay and not admissible in court.

We're totally anonymous and of no use in legal matters.

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#4

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/13/2013 5:48 PM

Good data might not be easily available for your question. Does your locale have an actuarial or statistical society that might have compiled such information? If so, consider joining.

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#5

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/14/2013 5:52 AM

The life of the tube will be determined based on multiple factors. How the ct is used and what type of scans are primarily performed and the frequency of the scans ( if this is a busy facility that happens to do a lot of abdomen scans the tube life will be greatly reduced since anode cooling is reduced compared to an infrequently used ct that normally does head or extremities). other factors that come into play is the type of ct. What kind is it? Is it a single slice? 4 8 16 64 etc?? The amount of slices the ct can perform makes a huge difference. Usually the ct displays slices on the tube instead of mas. Just convert the mas into mA and seconds to get the time. Another factor is periodic maintenance performed by the engineer and qc maintenance that should be done by the tech ie checkup on startup every day to properly warm up tube and proper shut down procedures. The cooling system needs to have to faults as that plays a major role in tube life. All these tests and reports are logged.

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Guru

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#6

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/14/2013 6:02 AM

Milliamperes seconds (if correctly read on the specs...), is an energy metering value, and the counter will be recording the total energy that has gone through the equipment (and the X ray tube). Therefore, if there is any mentioning of a maximum milliampers second before failure, in the equipment litterature/document, that will be the value to compare with the counter reading to see if the value was exceeded and expect a lifetime ending of the tube.(Mean Milliampesrs Seconds Before Failure ??).

I am not an expert in these equipment. What I stated is a possible deduction from the info supplied so far.

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Guru

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#7

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/14/2013 2:46 PM

MTBF or do you really want the rated end of life. I doubt any CT would deliberately run the tube to failure but replace it after a known interval or usage.

Different technology - sterilizer bulbs - have a limited life to be effective, but the bulb is still "lit". The intensity is not sufficient to work properly.

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Participant

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#8
In reply to #7

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/15/2013 12:39 AM

I need the MTBF to arrive at appropriate depreciation for its use.

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Guru

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#9
In reply to #8

Re: Normal Working Life of a Rotating Anode X-Ray Tube for CT Scan Machine

10/15/2013 2:11 AM

That sounds like a typical insurance adjuster response - not the service life that is usable (which will be shorter) than the MTBF when it dies or fries. I would argue you are trying to avoid payng out on a reasonable usable life.

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