In this paper a new method of emission tomography using coded apertures is analysed. The coded image of a radioactive distribution is created using a single linear Fresnel zone plate. The decoding procedure is performed using a computer algorithm simulating the optical phenomenon. This numerical reconstruction requires bidimensional Fourier transform algorithms. On the contrary, a linear Fresnel zone plate only requires a one dimensional Fourier transform algorithms is workable in most of the available nuclear medicine computers. The experimental results demonstrated the focalisation properties of this code (tomographic effect) and the parameters found after numerical reconstruction were similar to those expected from the optical theory. Practically, this technique should make it possible to perform morphological studies of moving organs, i.e. dynamic tomography which should be for example very helpful in cardiac studies.