Resolutions in imaging with Fresnel zone plate.

A coarse Fresnel zone plate (FZP) may be used as a large-area coded aperture for imaging incoherent sources. The longitudinal and lateral spatial resolutions are discussed on the basis of experiment using an FZP having 18 or 19 zones as an aperture. In this paper, it is then shown that the lateral spatial resolution is about 5 mm and the longitudinal is about 1 cm, respectively and it is appropriate to use the longitudinal resolution factor 3.7 as a guide to know the tomographic effect. These results may be extended for imaging incoherent gamma-ray sources. According to our experiments, radioactivity of several tens of a millicurie is necessary for imaging with 99mTc, when using X-ray film as a detector. Therefore, it is important to improve the detector in order to apply to the human organ imaging generally.