Scatterometry has been put into practical use for microstructure measurement of ultra-large-scale integration due to its high process compatibility. On the other hand, its application has been limited to periodic structures. By applying this method to isolated systems and using hard X-rays, it may be possible to significantly exceed a resolution of 10 nm, which is the limit of conventional optical measurement. We demonstrate the feasibility of this measurement by rigorous calculations. For this purpose, we measured the intensity of specular reflection and noise at the beamline of hard X-ray radiation. The virtual target is a 15-nm-wide lattice. The signal-to-noise ratio is low enough for a lattice with a period of 25 nm but 10 times higher for an isolated lattice.