Dear Jane Hill ,

a) I do not know in what context you ask that question. With respect to imaging, x-ray scatter (including backscatter) does not affect the resolution of the x-ray image. Although the image seems to be blurred when scatter shows up, it is not the lack of lateral resolution; it is the decrease of contrast due to increase of background signal via x-ray scatter.

b) For a highly collimated beam (e.g. at 1A) diffraction shows up in a plane perpendicular to the primary beam direction. The spots or rings showing up depend on the regular arrangement of the atoms ( i.e. the crystallographic structure) of the sample. There are various set-ups to measure this diffraction.

Please see for example:

https://en.wikipedia.org/wiki/Powder_diffraction

I may have been misinterpreted your question;

in this case please specify your question more precisely.

Thanks in advance

It depends on what class of materials you are using and on the angle of incidence