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Continuous measurement between two points approximately 2.5m apart

Discussion in 'Sensors and Actuators' started by Species, Oct 3, 2021.

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  1. Species


    Oct 3, 2021
    Hi, help gratefully requested please. I am a surgeon and use a 'c' arm xray in surgery. The radiation passes between the tips of the C. The C can be moved to take vertical or horizontal images, or anywhere in between as required. I would like to measure the distance between the two points of the C as they possibly open and close by up to 2cms which can distort the images.
    I would like to digitally measure the distance as I move the c arm.
    Many thanks
  2. Nanren888


    Nov 8, 2015
    Presumably there is something obstructing the direct path?
    Got a brand, model number and/or image?
  3. Species


    Oct 3, 2021
    Yes, the patient will be between the points of the c. But there may still be parts of the machine that would permit a laser measure. No specific brand. I want to be able to look at the moment between the ends to assess image distortion between brands.
    The C can rotate around 2 axes to allow imaging in the chosen plane
  4. Bluejets


    Oct 5, 2014
    I don' t see which points are 2.5 metres apart.....
  5. Species


    Oct 3, 2021
    The radiation emitter and the intensifier are on either end of the c.
    The photo here is of a relatively smaller one than normal. When the c moves the two end can come together or separate depending on gravity etc. This distorts the image
  6. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    This is obviously a medical device. We (at least I) strongly discourage you from any tampering whatsoever with a medical device.There are issues of liability involved. If the device has an issue, contact the manufacturer for expert support.
    hevans1944 and bertus like this.
  7. hevans1944

    hevans1944 Hop - AC8NS

    Jun 21, 2012
    I have to agree with @Harald Kapp and @bertus (post #6): talk to a sales person FIRST to see if this is a known problem, and if it is a known problem ask what the workaround solution is. Perhaps they will allow you to take a few x-rays of a phantom target to compare performance (legibility, contrast, focus) among brands. Yeah, riiiight!

    There is no doubt that the ends of the "C" arms will move toward or away from each other under the influence of gravity, depending on the orientation of the "C" framework with respect to the local vertical datum. The question is how much they move, in what direction do they move, and what affect does this have on the x-ray intensifier image? These parameters all need to be quantified and specified before deciding what measures will need to be taken to remedy the problem.

    Unfortunately, from the geometry of the system, including the patient support platform, it appears there is no direct line-of-sight between the ends of the "C" arms for any possible orientation of the "C" arm. Of course this could be perhaps be remedied by removing the patient support platform, or perhaps by. attaching right-angle prisms at each end of the "C" to bring an external laser distance-measuring beam a few centimeters perpendicular to the plane of the "C" arm.

    If this is a very serious problem, perhaps interfering with a necessary surgical procedure, the problem could be corrected if a mechanism were present to allow the x-ray intensifier plane to be moved toward or away from the x-ray source as a function of "C" arm position. This would no doubt require an expensive retrofit of the machine to accommodate a movable intensifier. Such a retrofit will probably void any original warranty, and a new warranty after the retrofit has been proven to be functional and adequate for surgical use, may not actually be available, Most manufacturer's repair reps will not service machines that have unauthorized modifications. However, for comparison purposes, you could use a portable plane-mirror distance-measuring interferometer...
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