What is the difference between an x-ray device and a linac (for medical purposes)?
In case both have to produce photons.
Linac:
X-ray device:
As far as I see the major difference is, that in case of the x-ray device, the rays impinge on some medium (crystals, GM-counter(?)) to produce an image. So, neglecting such a medium, are both devices conceptually the same? Not just in terms of "Yes, they produce irradiation" but also in a technical setup and so on. Or in other words: When placing crystals below a linac, could one speak of x-rays /x-ray images then?
I also wonder why the linac navigates the electrons towards the patient. In the case of the x-ray, the electrons and photons are orientated perpendicular to each other, while in the case of the linac, they are parallel.
Best Answer
For the diagrams you have, the biggest difference (which is the major reason for the design difference) is the energy of the x-rays that are produced. An x-ray tube with the above design typically gives off photons up to ~160 keV energy, which is the upper range of what is useful for making a medical image (higher energies have too many photons go through the body, and you lose contrast in the resulting image). Medical linear accelerators give x-rays of uptown ~23 MeV, which are very useful for treating tumors.
To summarize, they both produce x-rays, but at different energies for different purposes