EBME Forums Forums Free discussion Free discussion why not repair rx tubes? Inserts

The video is very illustrative; I would say that in one of the jeeps the chemical vats were being shaken to have them ready.

Yes; that video is a bit of a joke. I suspect the idea was that it would "reassure" those watching that all will be well on the battlefield (some hope). Also, where's the "genny" (engine-driven power generator)?*

It reminds me of a film (in glorious "Technicolor") produced by the US Army showing actual battle casualties undergoing surgery in a MASH type field (tented) hospital in Vietnam. Although supposedly also intended to "reassure", it was in fact so gory that I had to leave the room to spare myself the embarrassment of "losing my lunch".

About x-ray tubes ... yes, in fundamental terms they haven't really changed that much since the introduction of the rotating anode. Despite what many folk these days apparently believe, you can't really change the laws of physics (cue Scotty in Star Trek).

By the way, I have also seen "flash-over" in tubes, as well as along HT cables. Perhaps we should remind folk that HV is dangerous stuff. It can kill if you're not careful, and it's us folk (the engineering techs) who are often around when things go wrong.

It's not usually so bad if you are resident at a single hospital (or group of hospitals) as you get to know the machines. It is when you are called to a remote location having never seen the machine before that things can get a little "hair raising". OK, you can (and should) "proceed with caution", but at some stage you have to press that exposure button!

* But that's a nice shot of the half-track right at the beginning. The REME (maintenance and repair Corps of the British Army) used a version of those (maybe the M5 variant) right up into the late 1960's. They were modified with a crane jib on the front (for lifting tank engines and what-have-you). There was even a Dinky toy at one time! See Google for details:- "reme halftrack".

Here is an interesting presentation on the evolution of X-ray tubes, keeping in mind that it was written in 2016.

https://www.researchgate.net/public...re_of_the_X-Ray_Tube_Can_We_Do_It_Better

That's a good one; thanks for sharing. Some astute comments by good old Wilhelm, too.

That's an interesting picture on the last page. There are a lot of dishes there (many rusty ones too). SMATV would have been a good option. I wonder where that is (nice flat roofs for ease of installation and maintenance)?

I have noticed that page 7 of the document cited mentions the "Lamor formula" [sic]. I believe that the notation shown is actually the Larmor formula (in fact, its Lorentz invariant form). Yes, sad I know.

Anyone like to have a stab at the units in SI?

Sir Joseph Larmor FRS FRSE (1857 - 1942). Hendrik Lorentz ForMemRS (1853 - 1928).

Geoff, you really do have too much spare time on your hands...

Well, you might think that, Malcolm, but actually I remain quite busy.

I took a look at that formula (and a paper found on line) and could not readily deduce the SI units it supposedly needs. I found no mention of them in the "learned" paper either.

And no, I could not spare much time on it. But someone - a Medical Physics boffin, perhaps - must know.

Meanwhile, I'm not on here much at the moment as, having lost my broadband connection, I'm having to rely on sneaking in via random open Wi-Fi networks (such as the Bingo Hall nearby) on an old (and slow) laptop. It's times like this that tend to highlight the different capabilities of various web browsers. I generally favour Brave, but am having better results with FireFox at the moment. Different version of Windows as well.

Did you download the .pdf by the way? What did you think of it (are you an "x-ray" man)?

The tubes have not really changed much, but the digital side of things has really moved on since "my day". Back then we were suitably impressed with the Siemens "Exposure Points".

Nowadays there is stuff like the Deviation Index in Digital Radiography, for example. All very interesting, and aimed at consistent image quality and (or course) the ALARA principle.

Here's an easy one for you, Malcolm:-

DI :: Deviation Index
EI :: Exposure Index
EIt :: Target Exposure Index

DI = 10xLog10(EI/EIt) ... per IEC 62494

Example results range from something like -3 to +3, with -3 indicating severely under-exposed (try again using twice the mAs) and +3 indicating severely over-exposed (repeat using half the mAs). DI = zero is the perfect exposure being aimed for.

Anyone like to have a stab at the units in SI?


Forget it, I will use the little neuronal plasticity I have left for more satisfying tasks.

From the PACs that I manage, I am trying to do some work correlating the deterioration of X-ray beam quality (we have equipment with tubes that are almost 40 years old), user and exposure and deviation indices. I would like to take this opportunity to ask if anyone has a reference for modifying the dcm4chee administration interface to make visible the dicom fields associated with IE, TIE and DI?