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Gamma ray and Xray to RF?

  1. May 11, 2014 #1
    Hi guys,

    Could someone refer me to sources which explain and give examples for crystals which absorb xray / gamma ray and emit RF ?
    Meaning that if I radiate a crystal with xray I get RF so I can theoretically track its movement in the enclosed are.

    Thanks a lot!
  2. jcsd
  3. May 11, 2014 #2


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    Do you know that this can be done? Scintillating plastics will emit some light when struck by x-rays, but I am unaware of any material which converts from x-ray to RF.
  4. May 11, 2014 #3
    Why does it need to be RF? For one thing, depending on the wavelength, the resolution would be very low. You would be a lot better off from a tracking standpoint to use materials that emit UV or IR or something when hit with gamma or x-ray radiation.

    You mentioned an 'enclosed area', if it was in a vacuum, electron beams will emit xrays when they hit something.
  5. May 12, 2014 #4
    Hi, thank you for the comments!
    I do not know if there are crystals who do that, but I read some explanations on how xray removes an electron from lower shell energy while another takes its place and as a result the atom emits RF energy.

    litup I'm talking about cancer radiation for example, when the tissue you radiate sometimes moves with the person so I'm curious if we can track it by getting something back from the xray radiation on the tumor to see where it moved when the person moved.
    Why would the resolution be low?
    Why is UV or IR easier and where can I read of a technology that does that?

    Links would be very much appreciated
    Thanks a lot
  6. May 12, 2014 #5


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    the lower the frequency = longer wavelength = more difficult to resolve smaller objects, therefore lower resolution

    This also applies to radar for example

  7. May 12, 2014 #6
    Thank you Dave.
    So going back to the question, what material can be used to take xray/gamma ray and emit IR/UV and how can it be tracked from outside of the human body?
    IR can be seen using an IR cam, but if the transmitter is very small and deep inside the body it wont be seen too well.
  8. May 12, 2014 #7


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    Are you actually suggesting scanning a human's body with X rays at a level that's intense enough to activate a passive device? On the face of it, that seems contrary to Health and Safety principles.

    The Cyberknife technology could be the sort of thing you are looking for. There are many Google hits but the detailed information is spread rather thinly. Various different clues are used to track moving tissue. I remember a BBC TV programme about the Cyberknife system used at the Marsden and iirc, they used Ultrasound to help to track the movement of organs during breathing.
  9. May 13, 2014 #8
    Hi Sophie,
    We ARE using xray on cancer patients to kill cancerous cells. I suggest implanting a device that absorbs xray and emits some wavelength that we can track from outside that body so we know if the patient moved. That way we radiate only the tumor and not the healthy cells.
  10. May 13, 2014 #9


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    OK. (Having just had a course of RT, I can go along with that!!) Your idea is certainly worth thinking about - nothing should be discounted without some detailed examination. Target seeking is attractive when there is no side information available.
    If you are planning to use implants then why not go for something that can be observed directly with a penetrating radiation with a short wavelength? As I mentioned before, I reckon that you would need to modulate your high power photon beam in order to produce a detectable RF signal. That, in itself, could involve a modified form of Linac as electron beam source (?). If you are interested in sub-mm position accuracy then that would have to be the sort of wavelength needed. Imaging with sub mm microwaves could be difficult - quite a bit harder than with Ultrasound, I should think, because the processing of ultrasound can conveniently use phase information. To do the same with em waves could be a lot harder as the rf frequency gets higher.
  11. May 13, 2014 #10
    "'why not go for something that can be observed directly with a penetrating radiation with a short wavelength?"
    You mean besides radiating the Xray to treat the cancerous cells, also radiate short wavelength signals to the implant? I was thinking it would be easier if there was a material that absorbs xray and emits short wavelength so we can use current technology without changing or adding too much.

  12. May 13, 2014 #11


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    There is a conflict here, between imaging and 'blasting' - the dynamic range of any detector array could be a bit demanding for handling the direct beam.
    I was wondering whether a sort of technology like the new backscatter Xray systems used in airport security. You are already using scary levels of radiation on the actual target area so there must be easily enough arriving on the edges of the beam to allow some imaging of the scattered radiation. Having said that, the image forming would be a bit tricky as you can't focus 10MeV X-rays easily with anything afaik. Some sort of 'multiple eye' system (like some insects use) could perhaps work.
    As a matter of interest, how does Cyberknife look from your point of view? Most of what can be read is "seller's information" and very optimistic. To my superficial view, it looks a lot like what you are after (very expensive kit, though!!!)
  13. May 13, 2014 #12
    I've read through their website and its still not clear for me how they track the tumors?
    It sounds like the perfect solution other than the fact that you have to buy the all kit instead of an "add-on" to existing xray radiation devices used in hospitals.
  14. May 13, 2014 #13


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    In the film I saw, they had an ultrasound scanner involved iirc.
    Of course, Cyberknife does more. They use many (tens of) directions for the beams, which reduces the intensity a lot in the regions they are trying to avoid.An Oncologist I saw, said that the applications of Cyberknife were somewhat limited - but that could just be because he hadn't one to play with.
  15. May 13, 2014 #14


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    The tissue that you irradiate in radiation oncology does not become radioactive, so no, you cannot track it by looking at x-rays that it emits (since it doesn't emit any). In principle you could detect changes in the scattered radiation, but tumor doesn't scatter much differently than normal tissue.

    However, there are different ways to track a moving tumor during radiotherapy. Here is one that I particularly like since I know some of the developers personally:

  16. May 13, 2014 #15


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    A nice piece of kit but the MRI makes it very expensive - the imaging would cost more than the Radiographic source, I imagine. I expect a 1.5T MRI would have enough resolution (?). The use of fiducials (implants) is not as satisfactory but would be a lot less costly and I guess that's what the OP is after. This is where I reckon the use of ultrasound imaging could help cut costs. Movement tracking would be a piece of cake, relatively, as it's done all the time with digital TV processing.
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