In Storage Phosphor (SP) used for Computed Radiography (CR), the quite stable latent image remains due to impurities and the lattice imperfections by the existence of trapped electron and hole. The quite stable latent image appears again (Ghosting image) by the passage of time etc, is recognized as image, and becomes an artifact in a clinical CR image. This study verified the influence of Ghosting image on a clinical image by a physical characteristic and the subjective evaluation, and examined the method to delete this artifact by the exposure of ultraviolet light as a method of improving image. As a result, Ghosting image can be confirmed by the dose used by the clinical diagnosis study, and it is taken as deterioration of the granularity on a physical characteristic. The decrease of the granularity of about 15% (by winner spectrum) was admitted by the frequency band of 2cycle/mm in SP that had been used for a long term. As the method of improving these, Ghosting image was erased with the ultraviolet light lamp with the peak wavelength at 310nm, and has band from 290 nm to 320 nm, and is useful for the improvement of the image quality. In this study, we examine the influence of Ghosting image on a clinical image, and report on the method to delete them by the exposure to ultraviolet light radiation for the image quality improvement plan that uses the x-ray used for usual clinical diagnosis study.