Figure 4
Optimum photon energy En which minimizes the required number of incident photons per pixel (left axis) and the corresponding value of (right axis) for imaging copper in silicon (a) and protein in tissue (b). These values were obtained from the calculations of shown in Fig. 2 as a function of both background material thickness and photon energy, assuming SNR = 5 and δr = 20 nm. Also shown is the energy Eest found by setting μ−1(Eest) of equation (4) equal to the total thickness t of the background material. As discussed in Section 3.1, the required illumination per pixel in 2D imaging shown here is approximately the same as the integrated illumination per voxel in 3D imaging. |