| T O P I C R E V I E W |
| Ming |
Posted - 09/08/2021 : 03:11:03
Hello, everyone I'm new here.
I'm an orthopedic surgeon from china; I would like to buy 3 Geiger counters to measure the radiation generated by the C-arm X-Ray device during the minimal invasive fracture reduction and fixation operations.
One Geiger counter will be placed on the patient's body; one will be mounted on the surgeon's headband; and one for the environment behind lead protection. Each operation will be less than 2 hours, and the X-ray image may be taken a couple of times to hundreds of times. If the data can be transferred to pc for further analysis would be better.
I don't know which model is suited for my purpose. I will be very happy and grateful if some advice will be given.
P.S. I find some GQ Geiger counters in Taobao.com(a company similar to Amazon.com in the USA); the same looks but the model numbers are totally different from the GQ electronics category. Are the model numbers different out of the USA or they are fake? I leave the link and Picture below.
Many many thanks!
https://item.taobao.com/item.htm?spm=a1z0d.6639537.1997196601.35.22577484kgVYiB&id=634954363350
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| 5 L A T E S T R E P L I E S (Newest First) |
| Damien68 |
Posted - 09/14/2021 : 03:35:15
maybe the small pin diode detectors would be interesting for X-rays like this one:
https://fr.aliexpress.com/i/1005001291967523.html
I have already seen GeigerLog interfacing detectors like this one.
I do not know at all what it is worth but I think that I will rather look towards it.
It must be more directional than the GM tubes which can be a disadvantage, after that it is also necessary to interface several with software and hardware ....
Ullix could tell us about this.
these scintillator-free detectors measure gamma radiation in a fairly narrow energy band, to see if it might be suitable.
EDIT:
you can certainly detach the detector with a cable like this one (not tested):
https://www.amazon.fr/dp/B00SWYTDXG/ref=twister_B08SS8KBTM
(jack with 4 contacts)
NOTE: for general use this type of detector is very limited, but if we limit ourselves to x-rays I think it's worth considering this solution. (I have no experience on it, it's just for discussion).
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| ullix |
Posted - 09/14/2021 : 01:54:19
@Ming: This sound like an interesting approach to something new. I hope we will hear more about it!
The data can certainly be transferred to a computer, and I suggest my GeigerLog software for it:
https://sourceforge.net/projects/geigerlog/
Further, I would like to suggest to pay attention to something which has not yet been considered. So far the worry has been whether the counters will be sensitive enough to register the x-rays.
But since it seems unknown what the radiation levels will be, it could well be the case that the counters are too sensitive for your radiation field!
Every counter has an upper limit, and when reached, will show nonsense or plain nothing, like show zero at high radiation level! This has happened for some users already. In such a case, counters with a big and sensitive tube are the opposite of what you need!
It would be good if you could do a dry-run simply to establish the radiation levels to be expected.
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| GBG12 |
Posted - 09/13/2021 : 18:40:35
This may be a good use-case for these inexpensive detectors. Not for absolute dose measurements (for which commercial X-ray dosimiters should be used), but for real-time spatial comparisons. The C-arm device is supposed to shine the X-ray beam on it's detector with no leakage outside the edge of the imager. The CPM outside the imaging cone would show how well the collimator performs and if it changes over time. A dense object like a bone, artificial joint or surgical instrument may refract some rays outside the cone, which may affect the surgical team's dose or the placement of shielding.
The detector recommended seems to have a thin-wall tube that is better for detecting low energy x-ray pulses, and you will have to see how it responds to the pulse widths avaialble on your device. Having several units will allow checking against each other to ensure they work properly. Placing it within the beam will likeley saturate it. |
| kotarak |
Posted - 09/13/2021 : 12:54:03
Geiger counters are not energy discriminating devices - in other words they cant effectively determine dose unless they are calibrated with an X-Ray source matching the energy of your X-ray beam. The standard data given for the LND7317 GM tube is 58 CPS for 1mR/h BUT this is for Co-60 isotope with gamma energy of 1173 keV and 1332 keV. You can probably find out the Cs-137 calibration value for this tube but it will be still off 662 keV.
When you are using it for dose measurements with X-Rays (<100 keV) the efficiency curve is completely different and readings can be grossly underestimated or overestimated for the the dose.
Furthermore with a single measurement point it will be impossible to figure out the effective dose when the x-ray is very close and there are various shielding factors and as for calculating the equivalent dose you'll need to factor the organs exposed around the measurement point.
In other words - it is quite dangerous to rely on an off-the-shelf Geiger Counters for dose measurements - you'll need to consult Health Physicists and calibrate the dose function of these counters with an X-ray source of the same energy as your x-ray tube (probably 50-70 keV) just to get a crude dose estimate. |
| EmfDev |
Posted - 09/08/2021 : 15:46:00
Hi Ming, these listings are not fake and are legit Chinese versions of our products. The best one for your application would be the GQ GMC-3150. Depending on the pulse width of the x-ray machine, longer pulse width will get better result. |
