Patent ID: 7184516

Claim:
An X-ray image radiographing system for radiographing a subject, comprising: an X-ray source to emit X-rays; a digital X-ray detector to detect a digital X-ray image of the subject, wherein the subject is placed between the X-ray source and the digital X-ray detector in an arrangement to satisfy the following formulas so that an edge of the digital X-ray image is enhanced over an edge-enhanced width on which image contrast is sharply changed: 0.1 m≦R1≦10 m, and 0.15 m≦R2≦10 m, where R 1 is a distance between the X-ray tube and the subject and R 2 is a distance between the subject and the digital X-ray detector; wherein the digital X-ray detector is a Coolidge X-ray tube having a size D of focal spot defined by the following formula of 10 μm ≦ D ≦ 500 μm, and wherein R 1 is (D-7)/200 (m) or more, and wherein the digital X-ray detector has a pixel size of from 20 μm to 300 μm and the pixel size is 0.5 to 3 times an EB value which represents the half width of the edge-enhanced width and is obtained by the following simulation formula: EB= 2.3(1+ R 2/ R 1) 1/3 {R 2δ(2 r ) 1/2 } 2/3 +D× ( R 2/ R 1) where δ is represented by the following formula of δ=1−n (n is a refractive index of an X-ray).