ON THE PROCESS OF THE X-RAY IMAGE FORMATION (II) : The Limit to Recognize a Simple Figure (2)

Abstract

In recent year, X-ray photographs can be obtained by very low dose with high sensitivity photographic system. Such very low dose makes the image quality inferior because of the fluctuation of x-ray quanta so called "quantum noise". The prosess of the x-ray image formation was evaluated from a point of view that the x-ray images are formed by the accumulation of x-ray quanta distributed randomly. And the condition that the image of a simple-shaped small object can be recognized into background quanta was investigated. Under the assumption that the quanta absorbed by an object are N_s and that the average number of background quanta per area which is in the same projected area of the object is N_b, the condition that N_s is recognizable in background is mathematically led to the following formula : [numerical formula] Then the validity of this formula was experimentally shown using a computer and a simulation system by a gammacamera.